Can I test a R12 system with R134a for a few minutes?

[Charrie]

I completely replaced all the ac system parts on my 88 ford van about 6 years ago and charged it with R12 and used Motorcraft mineral oil. I used a Motorcraft E6DH compressor and a stock Ford tube/fin condenser.
At the end of last year i started seeing some water dripping in the passenger floor board and the vent temps had gotten cooler. I assumed that the system must be low on refrigerant and I would need to find and fix the leak the recharge the system.
So this year when I went to use the AC, here is what it is dong:

Starting the engine and turning the ac on to max but low fan. Ambient temp 70F. I connected the gauges and purged the hoses and both gauges equaled out at about 62F but it had been around 55F overnight and so the components and refrigerant was colder then the ambient temp of 70F
Cycle time was 3 seconds on and 15 seconds off.
High side pressures were 75 to 95 PSI
Low side pressures were 39 to just over 40 PSI

A little while longer with engine up to temp and the AC components starting to warm up:
Cycle time was 3 seconds on and 15 seconds off.
High side pressures were 95 to 115 PSI
Low side pressures were 35 to 37 PSI

I used a jumper at the clutch pressure switch, the suction side pulled down to 0 PSI at which time I pulled the jumper.
The high side went up to 115 PSI while the suction was at 0 PSI

I tried to add some refrigerant but it would not take any. When ever I would open the valve to add some, the low side instantly jumped up close to what the high side was.

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Second attempt the next morning.
So this morning while the temps were still below 70F I connected the gauges and installed a jumper in the clutch connector so that the compressor would run continuous.
The low side went down to -15 so I opened the low side valve to see if it would take some refrigerant. As soon as I cracked the valve the low side pressure started climbing back up towards 60 or 60 PSI so i closed the low side and let the pressure drop back down to 0 PSI. At that point I just barely opened the low side valve till it reached about 10 PSI and tweaked the valve so it stayed around 5 to 10 PSI. At one point I placed the R12 can on the radiator hose to get the can warmer. Eventually I was able to get about 10 ounces into the system.

At the very beginning I noticed the suction line was starting to sweat a little like it did the day before. I put a thermometer in the vent and had the fan on low. While trying to get the system to accept the refrigerant, i checked the vent temp and it was about 50F. Shortly after though with the engine and radiator heating up the condenser and other components, the suction line became warm and the vent temps went back to ambient temperature of around 70F

The compressor is noticeably louder then it was last year . With the extra refrigerant in the system the compressor is cycling even shorter, about one second

The high side pressures are 105 to 125 PSI
The low side is now bouncing 36 to 39 PSI
The readings were taken with the engine up to temp and the ambient air temp about 70F
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A local shop, without looking at the van, said that it was just low on Freon and that he would pull out the R12, add a conversion kit and fill the system with R134a. So I ask about the oil and he said they would just add a couple of ounces of rag oil! I left telling them I would have to think about this.


So I have a r12 charge on hand for the system but I certainly don't want to waste it. My main question is this.. for testing purposes, can I vacuum and charge the system with R134a and dye and then run the system just long enough to get some readings verifying if the compressor is good or bad without damaging the compressor? This would also disburse the dye to help look for a leak, if there is one. Also want to inspect and replace the orifice tube prior to vacuum at this time..

I would be more then happy to convert it to r134a if I could locate a parallel condenser. There seems to be quite the shortage on older condensers these days.

Any and all help and advise is more then welcome!
Thanks all.
Charrie

[Cusser]

So I have a r12 charge on hand for the system but I certainly don't want to waste it. My main question is this.. for testing purposes, can I vacuum and charge the system with R134a and dye and then run the system just long enough to get some readings verifying if the compressor is good or bad without damaging the compressor? This would also disburse the dye to help look for a leak, if there is one. Also want to inspect and replace the orifice tube prior to vacuum at this time.

I'm not a pro, so wait for more/better responses.

But I seem to remember some folks doing this or similar to test.

[tbirdtbird]

If the comp can pull down to -15 I doubt it is faulty. It does sound like you have a leak and are low on charge.
You do not have to have a fully charged system in order to leak-check. The dye and special glasses is fairly old school. If you can lay your hands on an electronic sniffer you would be way ahead. There is prolly enough R12 in there now to sniff out leaks. Be sure to sniff the evap drain (refrigerant is heavier than air). Also, put a shower cap around the comp (belt off), and leave overnight or 24 hrs, then put sniffer probe inside the cap. If the shaft seal is leaking, you'll need a new comp.
As far as actually using R134 to leak check, I suppose you could puff in about 20 psi hi and low, and then sniff. But I would not want to run the comp, since 134 will not mix with the R12 mineral oil, and the comp will not get any oil, and you will shorten its life.
Also, the lower the charge gets the less oil the comp will get, which again is bad. You could alternatively add some dye to the system now, assuming you have any R12 left in there, and run the comp briefly to distribute the dye.

Louder comp is not good and would seem to indicate it is starving for oil. I would run the system as little as possible or not at all until you get this straightened out. Tim, the site owner, may be able to get you a parallel flow condenser that would fit. He is very helpful. Call him.

These are my thoughts. While I have a great deal of mobile and residential AC experience, I am also not MACS certified, so I would wait for an answer from a higher authority

[JohnHere]

You probably still have enough R-12 remaining in the system to leak-test it using an electronic "sniffer." I would go that route instead of taking the chance of introducing R-134a into the mix for reasons outlined previously.

If not, pressurizing the system with nitrogen--not shop air, which contains moisture--is a viable alternative. You'll need a professional A/C shop to handle that for you, though, if you're unfamiliar with the process and lack the special equipment.

If you live in a state that uses chemicals on the roads in winter, pay particular attention to the metal refrigerant lines, especially any that are down low. These often develop pinhole leaks due to corrosion on vehicles such as yours.

[Charrie]

Thanks for taking the time to help and offer your advice and experience.
I sent Tim a message and they are out of stock on a condenser right now so it appears i am stuck with mine for now.

Part of my limited AC experience is from years ago when my dad had a mechanic shop and I remember they used a propane halide leak detector where I think the flame turned green when it sucked refrigerant in the tube.
Later I went on to learn control wiring for refrigeration equipment mainly replacing parts and rewiring the control panels of used compressors used in store refrigeration. I worked with several small companies and so learned a lot often being their helper while waiting to see if everything was going to work. But that was years ago.
Putting my system together was fairly easy because everything was brand new and it was basically just following the directions in the ford service manual.

I ask the guy at the shop I took the van to to check it with an electronic detector and he said: Oh those things are more pain then they are worth, they will show a leak at your spare tire! That was a recommended shop in my area but I think I might be better working on this myself!

I could buy a leak detector from HF. They are about $70 and seem to have pretty good reviews but you probably know how HF freight tools are. That is why i was thinking about using dye. If anyone thinks the HF detector would work or has a better suggestion i will surly listen.

What do you guys recommend I do from here? I am thinking like you all said, first find and repair the leak including replacing the compressor if necessary.
2nd go back with R12 if I can't find a parallel condenser. 3rd, thinking maybe need to flush the system depending on what I find once I open it up to replace the accumulator and orifice tube?

How much oil is normally lost is the system is low but now empty? Maybe that would depend o where the leak is, like at the compressor shaft?
Cant the compressor shaft be replaced? On the other hand I am thinking that the clutch looks like it has gotten warm and the compressor is a bit more noisy. I can buy a new compressor an clutch for around $250.

Should I flush the system if I change the compressor due to the front seal leaking and it is still working but a bit loud?

I do like the idea of a shower cap over the compressor which i would bet is the issue. Shortly after putting the system together I noticed a slight oil seepage around the front seal. I took it to a shop that was still working with R12 back then. The E6DH compressor has a short felt piece sticking out from the front housing. The owned of the shop dais that it is normal for the E6DH to seep some oil in order to keep the seal lubricated. That was 5 years ago and below is what it looks like now 6 years after install.

[tbirdtbird]

Your compressor seal is shot and the comp needs to be replaced, at the very least.
The gentleman who told you "Oh those things are more pain then they are worth, they will show a leak at your spare tire! " doesn't know how to use it.
We have found the dye to be not as sensitive as the sniffer. The halide torch is absolutely ancient history. If you picked up some AC info from that era, there have been a lot of changes and improvements since. I have a friend who muddles by with AC (from a different state else I would just fix it for him) who has done well with a HF sniffer. I have not used that brand myself. Also, if any dye was previously used, wherever that leaked out (before the leak was fixed) will still light up with the fluorescent light, unless the mechanic took the trouble to wipe off traces of the dye, which no one ever does. Then you won;t know a new leak from an old one that was repaired.

You need to adjust the sensitivity to low initially until you find the general area of the leak. Then you can better pinpoint, if needed, by adjusting the sensitivity higher. Remember, there are false triggers, so be sure what you pick up is reproducible. For example, your breath will set off any of them. Please do not ask why! I have no idea. But that is how determine every time we use it if it is working.

Do yourself a favor and before you commit to buying any parts at all, be sure to have Tim at least price them out. I have been extremely happy with his prices, and he ships faster than any other source I have tried.

I would suggest that you are getting a bit ahead of yourself. See if you can determine if there are any other leaks and report back. If you are patient, and willing to stay with us, we will be happy to walk you thru whatever needs to be done. As you have already figured out, you will be needed some new tools and equipment, such as a vacuum pump. And please avoid the "vacuum pump" sold by HF that works off compressed air. It is worthless and will not get you where you want to go, not even close.

[Charrie]

Thanks for the quick reply and advice TbirdTbird
Yes the shop I was recommended to was going to do a quick conversion To R13a and then start adding additional things like the compressor. They were pushing me to do let them do the job right then!

I will defiantly take my time as well as talk to Tim about the parts needed and stay here with you all for advice and coaching.

When I assembled everything 6 years ago i used new Green (HNBR?) O-rings and replaced the ones on the lines I received because i wasn't sure how old they were. I used red nylog on all the O-rings so all the fittings should come apart easy.

Again Thanks!
Charrie

[tbirdtbird]

Good. Generally o-ring fittings come apart easily. It is the large nuts that hold the pipe to the device (evap, comp, condenser, and such ) that sometimes do not want to let go. Don't force them. An old mechanics trick to loosening stubborn nuts is to actually tighten them a smidge first, this breaks the fine corrosion particles that seem to grip everything together. Although this may seem counter-intuitive, even to me, it usually does work on a stubborn nut or bolt. I knew a guy who could not remove the rear axle drain plug on a 1931 car to save his life. I told him to tighten it first, and Voila! He was very happy. Mineral oil fittings should come apart easily, tho.
I personally use blue Nylog. You must be ahead of the curve, lay people have never heard of nylog.
Generally if we open a system, we replace all the o-rings.
You can use the green o-rings on R-12, but the old school black is ok. Prolly harder to get these days.
I may be repeating myself, but if you use an outside shop, try to locate one that is MACS certified. And if anyone is gonna convert to R134, they really need to find a parallel flow condenser, else performance will not be up to par. But you already know that. If Tim is unable to get you one, there may be a generic size that will fit 'close enough' pending doing some tweaking of the mounting and hoses, to be located on-line. Should run you about $100.
Keep us posted.

[Cusser]

Your photo definitely looks like a compressor seal leak.

I do have one of those $70 Harbor Freight electronic leak detectors, and it has worked fine.

[JohnHere]

I agree that the front compressor seal is leaking due to the pictured oil stain. Probably, more refrigerant than oil has leaked out during six years.