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Class "A" motor home air conditioner problems Pages: 12Last

E4ODnut on Fri August 02, 2013 8:16 PM User is offline

Year: 1992
Make: Winnebago
Model: Elante 33 RQ
Engine Size: 460 CID
Refrigerant Type: R-12
Ambient Temp: N/A
Pressure Low: N/A
Pressure High: N/A
Country of Origin: Canada

Hi all,
I’m new to this forum and am hoping that others here will be able advise me how solve a problem I’m having with the dash air conditioning system on my 1992 Winnebago Elante 33 motor home.

First, a bit of back ground about myself. I am a 66 yr old semi-retired electrician. I have no formal training in refrigeration, but years ago I lived in a remote area where you either fixed things yourself, or did with out until you either sent the equipment out, or paid dearly to have someone come in. I bought a set of gauges, a halide leak detector and a copy of “modern Refrigeration and Air Conditioning” by Althouse, Turnquist and Bracciano. They served me well and I was able to keep my domestic refrigeration units running for years. Having said that, I never worked on automotive air conditioning and probably just have enough knowledge to be dangerous.

Now, to my problem. My Elante 33 is on a Ford chassis, 460 CID V8. The air conditioning compressor, condenser and filter/dryer are Ford items. The HVAC unit and hoses were made by a company called SCS/Frigette. According to the Winnebago tech support fellow I talked with recently, that company went out of business in the mid nineties and was taken over by another company of the same name. Some, but not all parts are available for these earlier units. I have some technical information and a parts list for the HVAC unit. I also have all the shop manuals for the Ford equipment.

The motor home is old, but has relatively few miles on it. We just completed a cross Canada trip with it and the air conditioner stopped working about 2/3ds of the way back home to BC. It was working at the start of the trip, but the weather was quite cold so I can’t say for sure how well it was working. When it failed, rather than hole up and try get it repaired at the time we decided to soldier on and have it checked out at our next scheduled stop in Saskatchewan. We went to a recommended radiator repair and air conditioning shop but they only made the problem worse, much worse. At that point I decided to take her home without air, learn what I need to learn and buy whatever equipment I need to buy and fix it myself, which brings me to the point where I am now.

Because there are several parts to this story, I’d like to break it up in three parts. The first part would be to try and determine what the initial problem was and what caused it. The second part would be to try and determine what the second problem in the shop was, and what caused it. The third part would be to try and determine the best course of action to get the system working again.

The system uses R-12. The high pressure hose from the compressor goes to the condenser. A filter/dryer is attached to the outlet of the condenser. There is no sight glass on the filter/dryer. There is a hose from the filter/dryer to the expansion valve at the evaporator. There is a pressure switch on this hose near to where it attaches to the expansion valve. The SCS parts book calls this a “binary switch”. As far as I know it is the only control for the compressor clutch. The expansion valve attaches to both inlet and outlet of the evaporator. The suction hose leaves the expansion valve and goes to the compressor. There is a Schrader valve service port in this hose near the expansion valve.

The system seemed to lose cooling capacity over several days, but the weather was extremely hot and humid, so it was hard to tell for sure. I believe the compressor was not cycling at all, but was running full time. When we stopped for the night I read through all my information to try get an idea of what might be happening. I started the engine up, the compressor clutch engaged, but there was little or no cooling air. After a few minutes running I noticed the expansion valve and high pressure line to it were frosted up. It was also frosted on this line where it attached to the filter dryer. I gave up, but tried the same test the next evening. Same thing. I shut the engine down and just stared at it for a while. As the frost melted, I noticed a few bubbles coming from the spade terminals on the pressure switch. Bubbles usually indicate a leak, so I disconnected the wires at switch so I couldn’t inadvertently engage the compressor clutch when running. The next night I had another look and found a drop of clear oil, which I assumed to be compressor oil on the underside of the switch.

Any opinions? Do you need any more information?

Thanks in advance,


Edited: Fri August 02, 2013 at 8:18 PM by E4ODnut

webbch on Fri August 02, 2013 11:15 PM User is offlineView users profile

First off - very nice and thorough description of system and the symptoms you are experiencing.

Sounds like you've pretty much diagnosed your problem. The binary switch shuts off the compressor when the pressure gets too high (too hot), and also turns it off when the pressure gets too low (too cold). Due to the leak, your pressure is going too low (hence the frost), but the switch isn't shutting off the compressor (hence the frost). Kill 2 birds with one stone by replacing the switch. Then vacuum and recharge and you may be good to go. I'm assuming this does NOT have any kid of thermostatic switch on the evaporator.

Are you planning to stick with R-12? If you plan to service it yourself, be prepared for about $700-900 for a 30 lb tank of R-12, or purchase a partial tank for less and hope it's pure (well worth it to take it to an a/c shop and have them verify the purity with a refrigerant identifier). I imagine it's getting difficult to find a shop that still services with R-12 these days. Are you sure the shop didn't put in "Freeze 12" (contains 80% R-134a, 20% something else). I had a shop do that to me 7 years ago on my truck...It's one of the primary reasons I started doing my own A/C work after that.

E4ODnut on Sat August 03, 2013 1:05 AM User is offline

Thanks for your prompt response, and the compliment as well. It's also reassuring to know that my understanding of the purpose of the binary switch would appear to be correct.

In my research I have not come across any reference to a thermostatic switch on the evaporator in this system.

Replacing with R-12 is not a practical option for me. My first thought is an HC replacement. Second, only under duress would be R-134A but I really don't have enough knowledge to say for sure.

Your diagnosis was my first thought. OK, I have a 23 year old system. The pressure switch develops a slow leak, draining the system down. Initially, it still works to an acceptable degree, but when the ambient temperature rises, and more demand is put on the system it leaks more to the point where the system is unable to keep up with demand and ultimately fails. Problem: Leak in system causes lack of refrigerant causes failure of system. Pretty simple.

But. I've been around long enough and have become cynical enough to accept the fact that most problems are not simple, but rather the unfortunate combination of several problems. I'm not saying that this is not just that simple problem, but what about the possibility of in addition to the leak through the pressure switch there is also a blockage, or partial blockage in the filter/dryer, causing a pressure drop across it, which could result in the frosting as well.

Is this a possibility?


NickD on Sat August 03, 2013 6:04 AM User is offline

Canadian law does not permit you to top off an R-12 system, want you to retro to R-134a. You can apply 12V directly to the compressor clutch coil with pressure gauges attached to determine if you even have any pressures or if they are correct. On a 80*F day, would expect around 30 psi on the low side and around 200 psi on the high side.

If not, then you have to retro first or get a US 609 certificate and sneak down here to buy some. With some risk since our 200 year old borders became so strict thanks to Bush.

Next question if the type of compressor you have, my oldie has a York with a sump, just like an air compressor and doesn't care if there is any refrigerant in the system or not. So doesn't have any kind of high or low side pressure switch to switch off the compressor. Assuming yours is an axially type that must pump oil using that so called binary switch. What's wrong with the English language, it has to be some form of a low or high pressure cutoff switch.

Same problem as you, Pace Arrow claims GM did the MVAC system, GM claims Pace Arrow did the system in this 1982 system, only kids working at Pace Arrow, tend to believe PA did this system with no record of it. But with the pressure switch, either a Japanese dual function switch or a cycling switch would give this protection against low refrigerant.

The problem with mine was that capillary gas tube sensing the evaporator temperature lost its gas and was about only two pounds low on R-12. In a way its a safety switch, if the evaporator temperature is below 33*F the compressor will not turn on, no concerns about high temperatures back then.

But that besides the climate control hitting the this evaporator switch with 12V the evaporator switch was the only control to cycle the compressor. Should open below 33*F and close again at 39*F. Does have an expansion valve and that was working okay. Strictly mechanical.

Since I couldn't even find anything even close or the name of that evaporator cycling switch, I designed my own.

But maybe you can find one that matches yours. Stick the end of your capillary tube in a glass full of ice water, contacts should open, let it warm to 39*F, should close, check that with an ohmmeter.

webbch on Sat August 03, 2013 10:48 AM User is offlineView users profile

I was not aware that it is illegal to service vehicles using R-12 in Canada, so I guess your only viable option is to convert to R-134a. You won't get any support for the use of HC refrigerants on this forum.

Unless the A/C shop you went to in Saskatchewan was operating illegally, they either did not add or remove refrigerant, or they added something other than R-12. And they mentioned nothing of doing a conversion? Did they even realize it was an R-12 system?

To convert to R-134a, you need to evacuate the system and perform a complete flush of all the lines and heat exchangers (evap & condenser) to remove all the existing mineral oil, as it is not compatible with R-134a. If you have a spec on the quantity of refrigerant oil (unlikely), add back that amount of ester oil (POE), then recharge to about 80% of the specified refrigerant charge with R-134a. Direct conversion of an R-12 system to R-134a typically results in poorer cooling performance, so many opt to replace the (typically) serpentine condenser with a parallel flow condenser. That frequently necessitates fabrication of new A/C lines, however. Also, I suppose the calibration of the binary switch that I originally recommended you replace may become an issue, as the operational pressure of R-134a are a little different.

Since you likely don't have the capacity information, you're stuck with putting in some estimated amounts for oil & refrigerant. I don't have much experience working with custom systems, so I'll defer to those who do on how much oil and how to charge by pressures and temperatures.

Sorry to hear about your laws in that regard. Keeping it R-12 would've been a lot easier IMO, caveated with the initial expense of obtaining the refrigerant.

As for the legality of r-12, Canadian Tire was actually prosecuted using it. (roll eyes)

Edited: Sat August 03, 2013 at 11:35 AM by webbch

E4ODnut on Sat August 03, 2013 11:46 AM User is offline

I have studied the SCS and Ford wiring diagrams and am reasonably confident that the only thing controlling the compressor clutch is the binary switch by the inlet to the expansion valve.

As for the compressor itself, because it is a Class "A" motor home, things get a bit grey. The Ford manual suggests that it has either the FX-15 compressor, or the FS-6, most likely the FX-15. The tag on the compressor itself has "SD-709" Ford and model 7611 Sanden International. Both ports are on the back of the compressor.

Before we get into what happened at the shop, can we determine from the information I have given you so far that the only probable cause of the system failure was a lack of refrigerant caused by a leak in the binary switch?


NickD on Sat August 03, 2013 4:29 PM User is offline

Anything like this?

LOW is OFF @ 28PSIG - ON @ 29PSIG
HIGH is OFF @ 454PSIG - ON @ 369PSIG

In English, we call this a dual function switch, some smarta$$ came up with binary, and from all the characteristics, is a dual function switch. Has nothing to do with cycling the compressor unless you have problems, is normally closed, and located in the high side. As long as your pressures are within, that 29-369 psi range, those two terminals are a short circuit.

You are dead certain you don't have a capillary tube stuck in your evaporator? Very typical of an expansion valve MVAC system as explained before. It prevents the evaporator from freezing up.

What you can do is to post some photos, you can find anything in a motorhome. At one time, over 3,300 motorhome manufacturers in the US, each with different ideas.

FX-15 has a bad reputation of being a Black Death compressor, used Teflon on the ring that would chip away block the expansion valve.

E4ODnut on Sat August 03, 2013 5:20 PM User is offline

The pressure switch looks similar to the one in your photo except that instead of having female threads, it has what looks to be about 3/8" national fine male with an O ring. It has the same adjustment screw centre top. The only markings are on the top. The first, very hard to read might be DCF21. The second one is quite clear, ZL27. It is located on the high side line to the expansion valve.

There is indeed a switch mounted on the HVAC housing with a capillary tube leading into the evaporator chamber. I had another look at the parts book. The illustration for my model shows a sort of representation of the switch but no reference number. Further investigation of other HVAC unit parts showed the illustration as a "thermostat". I went back to my parts list and found "thermostat" with the missing reference number.

Then I went back to the wiring diagram. Sure enough, there is a thermostat in series with the pressure switch conductors to the compressor clutch coil.

I hate it when I miss things like that. And I call myself a professional!

Oh, one more thing. Just for reference the parts book shows this model as having a capacity of 32 oz. R134A. It doesn't give capacity for R-12 or the amount of oil either. I'm assuming that mine was one of the last to use R-12 in 1992, and later years used the R-134A. I believe 1993 was the last production year for the Elante model.


Edited: Sat August 03, 2013 at 5:25 PM by E4ODnut

webbch on Sat August 03, 2013 7:11 PM User is offlineView users profile

OK, so you have a thermal expansion valve, or TXV. Apparently the binary switch is only to protect the compressor from damage at excessively low or high pressures. The TXV regulates the refrigerant flow (while compressor is running). The bulb should be attached to the evaporator outlet. The bulb should also be insulated (generally use prestite tape, sometimes called cork tape) so that it's truly sensing evaporator outlet temperature, and not cabin temperature. A non, or poorly insulated bulb could make an otherwise good TXV have excess flow, potentially resulting in the frost you were seeing. Or sometimes the valve itself goes bad.

E4ODnut on Sat August 03, 2013 7:56 PM User is offline

The learning process continues.

Now it would appear that the pressure switch is just a safety device, not an operating device as I had thought. The compressor clutch would appear to be cycled off and on by the temperature switch which should sense evaporator temperature. The temperature switch capillary tube disappears into the evaporator housing, but it is likely impossible to see exactly how and where it is mounted without removing the HVAC unit, which is a huge job.

Now, I found an interesting thing about the expansion valve. It has a small diaphragm and very short capillary protruding from the bottom next to the low side outlet. The capillary is only about 1 1/2" long and just curls back on itself next to the diaphragm. The valve body is aluminum and has some numbers stamped on it. 126 830 02 84 Eaton. The interesting part is that there is what appears to be the Mercedes Benz TriStar before the numbers. I did a search on that number and found it is equivalent to the 126 830 03 84 expansion valve which seems to be available as a Mercedes Benz replacement part.


Edited: Sat August 03, 2013 at 8:11 PM by E4ODnut

NickD on Sun August 04, 2013 5:35 AM User is offline

This gives a hint to us as to what you have.

Has to be a labor of love or insanity, RV dealers in north Central Wisconsin charge 125 bucks an hour, some are not the brightest. And in the case of Pace Arrow had to remove that 8' wide dash to work on the AC system. And dead positive that dash was installed before they attached that entire single piece front end to it.

First step was to connect the manifold gauges to see if I had positive pressure, did, then use an electronic leak detector to check for any leaks. Then to clean the entire system up. Used a 12 V power supply to directly activate the clutch coil with the engine running to check the running pressures, was low. Charged it properly, in my case with R-12 and did get nice cold air. Then to redo the electrical system to learn why that wasn't working.

Heck with the dash removed, redid all the wiring under that.

Just one more little issue, the mode door weather stripping was all shot, so redid that. Then with the price of gas as high as $4.50 a gallon, $4.20 right now, hardly use it. It was under two bucks a gallon when we first got it.

mk378 on Sun August 04, 2013 9:46 AM User is offline

The first thing to do with a leaky system is of course to find the leak(s). It appears that you have found one at the switch. Confirm that with an electronic detector or soapy water, and replace switch. Many of the switches have NPT thread (really old) or straight threads with an o-ring (more modern). Once you match the fitting type, the switch is a rather generic item, they all operate at about the same pressures. With ordinary screw-in switches (not the one with a valve like Nick posted) the pressure must be zero before unscrewing.

You have a block type TXV. The usual sensor capilary is internal, it only needs to go down to the outlet side of the valve (the big pipe) to detect the evaporator outlet gas temperature. This makes installation a simple bolt on of the valve as a unit. Old R-12 TXV's work with R-134a, it is typically not replaced when converting.

The "binary" pressure switch is a safety device. It should be closed circuit under all normal operating conditions. Serious over pressure (loss of condenser cooling, or overcharging) or under pressure (leak out) will open it to protect the compressor.

Replacing the receiver-drier is imperitive when converting refrigerants, and still a very good idea if staying R-12. It is an expendable part like an oil filter.

Edited: Sun August 04, 2013 at 10:00 AM by mk378

E4ODnut on Sun August 04, 2013 10:36 AM User is offline

I suspect that the reason the system failed was simply a lack of refrigerant caused by the leaky pressure switch, but is it possible that there was another problem as well?

What situations can cause the line from the accumulator to the expansion valve, and the expansion valve itself to frost up with no cooling from the evaporator?

Is it possible the accumulator was plugged, or partially plugged?

How about a restriction in the condenser or evaporator?

How about a malfunction of the TXV valve?

Are any of these a possibility as well?


Edited: Sun August 04, 2013 at 10:42 AM by E4ODnut

webbch on Sun August 04, 2013 11:43 AM User is offlineView users profile

Diagnosis must proceed based on available data. Currently, the available data is that there is clearly a leak and low charge condition. Sounds like you have a thermostatic switch that controls compressor engagement, but it's unclear (to me at least) at this time if there's an issue with it. The leak must be fixed (by replacing the binary switch) and system recharged before attempting to diagnose anything else. Once the system is recharged, high/low side pressures and associated ambient and vent temperatures will allow further evaluation of the state of the system.

mk378 on Sun August 04, 2013 12:50 PM User is offline

If R-12 is not legal in Canada, what refrigerant did the shop charge with? Was a "leak stop" compound added?

E4ODnut on Sun August 04, 2013 1:37 PM User is offline

OK. Let's proceed to chapter two of the saga.

When I got to my destination in Sask. I had been given the name of a shop that specialized in radiator repair and auto air conditioning. I phoned them up and told them that I had an R-12 system in my motor home that was no longer cooling. The compressor seemed to run all the time when I called for cooling but there was little or no cold air and the line to and the expansion valve would frost up. I also told them that I had seen bubbles on the pressure switch when the frost melted and also a trace of what I believed to be compressor oil on the switch. I told them I suspected that the system was low on refrigerant because of the leak but having only basic refrigeration knowledge, I couldn't know for sure. I asked them what my options were.

Their answer was simply "replace the R-12 with HC" and they could get me in the shop the next morning. I had done some research on HC as an R-12 replacement and quite frankly, couldn't see any reason why not to in my situation.

I took the motor home to the shop at the appointed hour. They evacuated the system from the low side service port near the TXV and removed the pressure switch. They pressure tested it on the bench and confirmed that it was leaking. After some time, they were able to locate a replacement switch elsewhere in the city. They installed the switch and pulled a vacuum on the system through the low side service port. The vacuum procedure lasted a couple of minutes. I had asked them if they needed access to the compressor and high side port. They replied that they didn't need to and could do everything from the low side. I asked them if they needed the charge fill specifications for the system. They replied that they didn't need it. They did not replace the filter/dryer.

They connected a pressure gauge and what looked like about a 10 lb cylinder of refrigerant to the low side. They also added what looked like several ounces of compressor oil to oil adding device on the gauge set. Then they had me start the engine and run it about 1000 RPM. During this time I could hear the compressor cut in for a fraction of a second and cut out for about 5 seconds. After several minutes they asked if I was getting cool air. I was not. They asked me to shut the engine down and they disconnected the cylinder saying that they were out of product. Then they connected a small can of RedTek 12A and had me run the engine. Still no change in cooling but after what I think was a total of 3 or 4 cans the compressor would cycle faster.

Then there was a rather loud noise and what appeared to be steam or vapour poured out from the engine bay. They told me to shut the engine down, which I did. I asked if it was coolant or refrigerant. The reply was refrigerant. The system continued to discharge for almost 5 minutes, refrigerant and oil mix. They determined that an elbow on the condenser had ruptured.

At that point I had enough. I told them that I didn't have the time to do anything else here and would take her home without air. They said they could repair the condenser and convert the system to 134A, but at that time, I just wanted out. I was still 1700 KM from home and didn't want to risk anything else.

There is another small part to this chapter, but I'll leave that for the moment.

What do you think happened and why?


NickD on Sun August 04, 2013 2:19 PM User is offline

Originally posted by: E4ODnut
I suspect that the reason the system failed was simply a lack of refrigerant caused by the leaky pressure switch, but is it possible that there was another problem as well?

What situations can cause the line from the accumulator to the expansion valve, and the expansion valve itself to frost up with no cooling from the evaporator?

Is it possible the accumulator was plugged, or partially plugged?

How about a restriction in the condenser or evaporator?

How about a malfunction of the TXV valve?

Are any of these a possibility as well?

Have to post pressures. Static, idle, and at 1,500 rpm. If your system was never worked on, and is 32 ounces, if you were losing a very difficult to find one ounce leakage per year. You only have ten ounces left.

mk378 on Sun August 04, 2013 4:20 PM User is offline

Frost after the receiver very likely means that the receiver was blocked. There shouldn't be anything cold until you get to the TXV. It appears the pressure switch is after the receiver, thus it did not protect very well against over pressure in the condenser before the blockage. Evacuating only through the low side and not watching the high side while charging is very substandard service procedure. Adding more oil just for the heck of it is not good. If you put a bunch of refrigerant in and it is not cold, the answer is generally not to put in more refrigerant. An undercharged TXV system does not normally cycle, rapidly or otherwise.

Having a few pounds of HC blow out in a big cloud you're lucky no one got blown up.

E4ODnut on Sun August 04, 2013 8:21 PM User is offline

I think we are making some progress here.

My latest theory is that I had two problems. The first, and most obvious was a lack of refrigerant caused by a slow leak in the pressure switch. The second, possibly related to the first may be a blockage, or partial blockage in the filter/dryer.

Oh, one question, filter /dryer - receiver? all same thing?

Now, what came first, the chicken or the egg?

Did the lack of refrigerant cause a blockage in the filter/dryer, or did the possible blockage in the filter/dryer cause an over pressure situation and rupture the pressure switch without tripping it?

For that matter, what can cause a blockage or partial blockage in the filter/dryer?

The thought did occur to me at the time, even though my understanding of the nature of RedTek 12A was that it was not extremely flammable, the fact that there was a whole bunch of it pouring out at pressure made me very thankful that my ignition system was in good shape and that the alternator brushes weren't arcing.


Edited: Sun August 04, 2013 at 8:29 PM by E4ODnut

NickD on Sun August 04, 2013 8:57 PM User is offline

If this is a Ford system, in this era, used those infamous spring lock couplers for everything. A smaller tube plugged into a larger tube separated by a couple of O'rings held together with a spring.

Would be darn lucky to hold a charge for three years let along 21 years. Never assume where a leak is at.

Most of us here are not exactly fans of hydro carbons, and they are a precise blend of propane and butane to be close to the correct pressures. if one of these gases leaks out, pressure balance would and does go crazy besides the hazards of it.

Let's talk about an R-134a conversion.

E4ODnut on Sun August 04, 2013 10:16 PM User is offline

This is a Ford system, or rather, a partial Ford system. There are no spring lock couplers in the air conditioning system. There are spring lock couplers in the fuel injection system but they have given me no grief.

I have gone through some previous posts on this forum, just to get a sort of feel for things around here and I do get the impression that HC replacements for R-12 are not exactly favored. Rather than get into that subject at this point I would prefer to try analyze what went wrong first, then get into what would be the best fix. I hope that won't offend anybody.


NickD on Mon August 05, 2013 5:30 AM User is offline

I am not even sure about Canadian law regarding the use of HC's in MVAC systems, in the USA, its against the law. R-12 was made specifically for MVAC applications that represents less than about 1% of the CFC usage. But yet no major organization objected to this, the rest of the banning didn't affect me one way of the other, and if they wanted it recovered, that was fine with me.

With paint spray cans using propane as a propellant, at first it was crap, just went back to my spray gun that dates back before spray cans were even invented. With my daughters, if they wanted to use hair spray, go outside and use it, didn't want propane spread all over the inside of my tight home. But they finally quit using that crap. But with MVAC, that put many of us in a very desperate situation. So why wasn't there major suing against the likes of DuPont and all automotive manufactures? We never manufactured asbestos, but used it and were forced into a major recall that almost bankrupted us.

From all reasonable considerations, CFC's were made from the dust of the earth, and to dust they shall return. One of the greatest scam artist of the world, Al Gore started all this stuff, and even Obama is dumb enough to believe him.

With Ford in particular, their one cure for converting to R-134a was to change everything from the firewall forward, and this is the predicament you are forced into now. And at your expense, you are a victim of this as well as the rest of us. You purchased this vehicle in good faith.

But in pure technical terms, R-134a is actually a superior refrigerant than R-12, and apparently your R-12 system 21 years old is already shot. If your vehicle is worth it to you, suggest you do this conversion. The only problem in converting to R-134a, your system was designed for R-12, but using R-134a in a system designed for R-134a, you should see an improvement.

mk378 on Mon August 05, 2013 9:06 AM User is offline

Since the condenser is blown anyway, look at upgrading to a parallel flow type. It will give better performance with any refrigerant.

The pressure-temperature characteristics of HC don't really match a TXV calibration, leading to strange recommendations from proponents like mixing it with air to make it "work". It seems OK in CCOT systems though.

E4ODnut on Mon August 05, 2013 10:36 AM User is offline

As I mentioned previously, there is another small part to chapter two.

After returning back to our camp site after the shop fiasco, I was troubled as to what may have gone wrong. This should have been easy. Evacuate the system, change switch, pull a good vacuum, re-charge with HC. I was also troubled by the fact that they didn't connect a high side gauge, didn't replace the filter/dryer, did a rather short vacuum pull down, did add oil and didn't replace the refrigerant by weight. I got into my books again and did some searching on the internet.

I was going to just write the experience off and be happy to have gotten out of there with no more damage than what I had already collected, but it bothered me. I was convinced that they had screwed up somewhere and I wanted to know what happened. I decided to put on my diplomat's hat and go back to ask some questions. So I did.

I asked them why they didn't install a high side gauge. They replied because they didn't have the necessary adapter. I asked how much refrigerant they had put in, the answer was "3 cans" I found this odd, because I had heard them speak of 4 cans at the time, plus what was in the larger cylinder. I asked if they had an explanation why the condenser ruptured. They said it must have had a weak spot. I asked them why the pressures got so high. They said they just didn't know and there should have been a high pressure bypass on the compressor. It was difficult for me to tell for sure, but at the time I thought I heard them mention jumpering the pressure switch so the compressor clutch would stay engaged. I'm not sure about that one though.

They offered to repair the condenser at no cost to me if I would re and re it but didn't admit any blame for the condenser failure. I figured that this was probably the best I was going to get and accepted the offer.

So, as it stands now, the system is back together. I hope they did a good job of the repair. They said it was pressure tested to 200 PSI. Only time will tell. I still need to purchase a new pressure switch as they removed the replacement ad re-installed my old one. The compressor has not been run since the incident. The system is now closed but at atmospheric pressure , no doubt mostly full of air. I have an undetermined amount of oil in the system. I may or may not have blockages or partial blockages in the condenser, evaporator, TXV and filter/dryer.

Before I go on to chapter three, which will be to get the system up and running again, I would really like to try determined what went wrong so I can put that out of my mind and proceed with the fix.


webbch on Mon August 05, 2013 2:26 PM User is offlineView users profile

What did the shop do wrong? Pretty much everything they touched. The ones that come to mind immediately are: Not using a high side gauge, charging by cans instead of weight, using HC refrigerant (nearly blowing themselves and you up in the process it sounds like as well), the testing of the condenser to 200 psi isn't really much of a test (I'd expect any condenser to be capable of at least 375-400 psi at a minimum).

So rather than losing any more sleep over what these hacks did, channel that energy toward the R-134a conversion, if having A/C in the vehicle is important to you :-)

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