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1994 Ford Taurus SHO HIGH side connection port leaking Pages: 12

cmeseadoin on Fri May 09, 2008 7:39 AM User is offline

Year: 1994
Make: Ford
Model: Taurus SHO
Engine Size: 3.2L
Refrigerant Type: R134A

Greetings again,

I'm having an issue with the A/C on my 1994 Ford Taurus SHO. I drove the car to work yesterday and came home, parked it and the a/c was working fine. I then came out a couple hours later and cranked the engine and turned on the A/C. Nothing, was blowing hot air. I could hear the compressor clicking ON then OFF immediately over and over. I knew I had more than likely lost the charge, so I got out, opened the hood and the HIGH side line was coated in oil at the top and it was leaking refrigerant from the end of the valve?? Sounded like someone letting air out of a tire. I went on to dinner, came back and she was still leaking slowly, so I stuck a blunt small screwdriver down in there and depressed the valve and reseated it and it quit leaking. This particular HIGH side connection service port does not have a schrader valve in it like a car tire valve, rather, it has what looks like a little ball bearing that is spring loaded and when depressed, the valve is open and when you let go, it closes itself. Because I had not lost the entire charge due to the leak slowing down as the internal pressure decreased, I still had some pressure in the system. I stuck my manifold gauge set on it and recharged it till my pressures and vent temps were about right again. I took it for a spin and it was working fine, blowing cold, and seemed to not want to leak anymore. So, I parked it for the night, came out this morning, flipped on the a/c and it is still working. I drove to work, popped the hood and sure enough, the HIGH side port is leaking again. It was coated in oil and you could hear it hissing. (less this time than last, but still leaking). I grabbed a ball point pen from the car and depressed the valve and made it leak big time really quickly, then let it go and reseat itself and it shut up again. Why is this valve doing this? Is the connection on the line just shot or is there potentially some other causation for this? I am not sure if this system has an orifice tube in it, but I was curious if there could be something the matter to where I am gaining way too much pressure in the line and she's popping? When the gauges are on, the high side pressure is well within the norm. I have no idea where I could get a whole new line including this service port if I have to replace the line. The entire front end of the car has to come apart to put that line on. It is a MAJOR job due to the construction of the car. I had to put a compressor coil on it and what a job!! I was wondering if there was a little cap that I could install over this leaking service port that would seal it?? The problem with that is that this HIGH line, on this car, is RIGHT at the lowest point of the hood line and if I make that connection port on the line too tall by adding a cap or something to seal it, my hood will hit it and not close. Has anyone got any idea here why my service port is leaking like this? What a STUPID problem to have with the a/c. Does anyone know any companies that deal in OEM refrigerant lines? Any help is greatly appreciated.

Chris

Chick on Fri May 09, 2008 7:45 AM User is offlineView users profile

First, you will be able to close the hood with the cap on. The cap is the "primary" seal on those systems. If you have the high side port with what appears to be a "ball" inside, then the whole port should be changeable, if it has a shrader valve, like a car tire, then the shrader valve is replaceable, but first, get the cap and put it on...Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

GM Tech on Fri May 09, 2008 8:51 AM User is offline

Most any parts store will have that generic high side cap- it is the primary seal- never run a system without the caps- I see it all too often- cars without a/c caps- why? I guess people lose them and don't bother to replace them-- I keep a box full just for these situations...

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

cmeseadoin on Fri May 09, 2008 9:02 AM User is offline

I was speaking of closing the hood with another cap over top of the connection fitting, not the factory black cap seal itself. Since the connection is leaking. I have spoken to a good friend of mine this morning and he seems to think I may have an orifice tube issue with the car causing the pressure to build and leak from the high side fitting. I will have to find out where that orifice tube is and whether the lines comes apart for replacement or if I have to cut it. Secondly, the black cap that goes on this fitting broke last night when I screwed it in. The HIGH side service port has a small threaded section down in the fitting and the part of the cap screws into that broke off flush with the top of the rest of the cap. I had to get it out with a little screwdriver. Now I don't have a service port OEM cap for it and need to find one. This is not a generic cap, it is different and screws with threads probably the diameter of a pencil on the inside of the service port.

How is the whole port changable? The port is part of the entire line that runs from compressor to the condenser and the port is nothing more than a fitting welded onto a t-conenction so that a gauge set can be connected to the line. None of that comes apart to my knowledge nor does it separate from the line. you'd have to put a whole new HIGH side line in the car with the connection port and fitting on it. It makes no sense to me that this fitting which has been on the car for 14 years suddenly is leaking. I am believing that I might have a problem causing it to leak, hence the common orifice tube blockage on these cars. I woudl think if this were the case, I'd see HIGH high side readings and LOW low side readings which I cannot say I have seen.....but this might explain my other post on here about the a/c vent temps increasing while driving. I might have a partially blocked orifice tube.

Chick on Fri May 09, 2008 10:04 AM User is offlineView users profile

I don't have a 94 in front of me, but I believe your right as to changing the line, but not really sure.. Anyway, it is possible that your old cap did not have the rubber gasket in it, and then it would leak. Try a new cap with the rubber gasket in it..As stated, the cap IS the primary seal.. If the leak is that bad, you have to then change the port, even if you have to change the line. Don't go changing the O tube until you know what the pressures are, I see you don't have them listed. The high side is only high while the car is running, and drops to the same as the low side when off..If you have cooling, chances are the O tube is fine..Check the pressures while running, and change the cap to one with the rubber gasket in it..Hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

GM Tech on Fri May 09, 2008 10:04 AM User is offline

Once again- Buy the plastic cap (they are almost all the same- generic or not) and put it on- it will seal off leaking valves- it is designed to do this- it has a rubber seal inside it to seal on the top of the port- so whether or not the ball valve is leaking is no issue- put the PRIMARY sealing plastic cap on and you troubles will be gone.

I just did one the other night that was spitting refrigerant- put the cap on good and snug - waited an hour- leak checked it- absolutely fine-- the ball valve is in there to seal the system good enough to allow you to put the cap on and seal the system-- without a good cap on it- you will continue to lose refrigerant.

High pressure will not cause it to leak more or less often-- The cap can withstand all that system has to offer- regardless of high side pressures....You got to believe in that cap.......I can't say it any better.......

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Chick on Fri May 09, 2008 10:17 AM User is offlineView users profile

Just to add, I did have a newer one in the yard, and they do use a big bore shrader valve which is replaceable should the cap not hold the leak in..No big deal other than to change it, the system must be empty, but as GM tech stated, buy a new cap first, make sure the rubber gasket is in it and it "will" stop the leak, don't over tighten it though, thats why the other one probably broke...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

cmeseadoin on Fri May 09, 2008 11:44 AM User is offline

I'm getting some good education here......I would never have thought that the silly little black screw on end cap would be what does most of the sealing....I have noticed for months under the hood that there is JUST A LITTLE bit of refrigerant oil sitting on top of that cap no matter how many times I wipe it off and it comes back. Yesterday when it was just hissing, I thought that either the connection had blown and the valve was no longer doing what it was supposed to, OR there was too much pressure in the system for whatever reason even though I have not seen that while having guages on it. It seems normal, so the O-tube was a big question for me because I cannot see that in the pressures.

So, when I went to screw the cap on tighter yesterday, that is when the core broke out of it and left me holding the cap with a center core down inside of the big bore high side connection fitting. So, a generic high side fitting cap from the auto store will seal it? If that is how that cap works, I would have never known. I would have thought that for that system to have held a charge for 14 years trouble free, there is no way that a stupid fitting cap would hold that charge in against a slightly leaking fitting by design. That would be like having a leaking schrader in a car tire and just by screwing on the cap it would take care of it. I guess these are made differently with that seal. I will def. try this as I can come up with NO objective data to prove blocked O-tube.

My pressures are in my head because I am at work and I can't remember exactly, but high at idle was like 205 and low was maybe 30-35.....at around 2K rpm maybe 250 high and 20-25 low. Seemed in the range of normal to me.

cmeseadoin on Fri May 09, 2008 1:43 PM User is offline

Went to lunch, picked up a couple high side caps and stuck one on good and tight........seems to not show any signs of leaking now, but will have to see how the refrig. charge holds. Will follow up. It's 85 and humid out there, blowing 36-39.9deg. at idle once she's been run for a bit and ices down to about 33-34 while driving and when the compressor is cycling while driving, it goes from 34ish to about 42/43deg. when the compressor cycles out, then back to 33-34 when it engages again. I did not think that I should see an 8-10 degree fluc. when the compressor is cycling as I am driving, but seems to be working fine. We'll see about the connection port leak. Thanks to all who helped.

Chick on Fri May 09, 2008 2:24 PM User is offlineView users profile

Just remember, it has been leaking and you might be a bit low. No big deal if only a little, but you don't know how much..You might want to recover and recharge system amount back in before the summer hits hard.., the refrigerant does carry the oil, so a low charge, even while cooling, can lead to problems down the road... hope this helps..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

cmeseadoin on Mon May 12, 2008 10:32 AM User is offline

Ok, so I have the leak fixed and she seems to be holding the charge fine. What I did was went ahead and pulled it down, pulled a deep vacuum on it for an hour and then shot it back to the OEM 2lb charge of R134A. I figured I'd been screwing with it so much that I might as well totally do it back to spec.

What is interesting is that I am still undecided on the operation of the system. The A/C seems to work fine, but I am still seeing erradic vent temps as the compressor cycles. The problem with an auto-a/c system is that if the air is not ALWAYS ice cold, there is too much window surface area that creates solar radiation and the interior warms up. If you are not putting out at LEAST 40 deg air all the time IMO, you might as well open the windows as the a/c is worthless. The problem I am seeing with this car is that I'm icing the air down to about 35 degrees but then the compressor cycles and I watch the air temps climb back up to as much as 46 degrees before the compressor re-engages and she starts cooling down the vent temps again. It is a cycle that happens over and over while I drive. The vent temps go to 35-38, then when the compressor kicks out, I can see the vent temp climb to the 45-48deg range then back down again over and over. When you have 35 deg air one minute and 46ish the next, that is worthless. I do not remember this issue before with the car and seems to be new. I have it charged to OEM refrig. charge and all system operations are working. The compressor runs and kicks out and cycles like it seems it should, my pressure seem well within spec and my vent temps seem right on. Why is it seeming that the air temps are being allowed to climb TOO friggin' high before she starts compressing again though?

Does anyone know what factors go into the compressor engagement on this particular car other than refrig. pressure? Is there a thermistor in the evap or anything monitoring the evap temp that the air is passed through? What about the orifice tube failure/blockage symptoms? I do not see any unusual HIGH high side readings and LOW low side reading, are there other symptoms? I know this is a CCOT Ford A/C system. Like I say, the ONLY problem that I think I might be having is WHY in the hell are the vent temps climbing +-10 degrees as the compressor cycles or is this just by design on this car? I don't everr recall this from the past. Thanks!

GM Tech on Mon May 12, 2008 11:36 AM User is offline

Every cycling compressor system does exactly what you describe-- how else would it avoid freeze-up unless the evap warms slightly? Under heavy load- when ambient temps are about 85 degf and above the compressor will run continuously and you will not notice the vent temp changes- it will remain constant because the compressor remains on--- What is going on is that you have more capacity to cool than what is needed- and something has to give or you will soon ice up-- and you would complain that there is no cooling at all-- you can't blow air through ice!!! I get those vent temp complaints from "scientific type folks" who keep a thermometer in their vents-- I tell them the compressor is cycling as designed-- and when it gets really hot and the compressor demand is up- the compressor will not cycle and the temps will be consistent..........

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

cmeseadoin on Mon May 12, 2008 12:39 PM User is offline

I agree with everything stated about "typical a/c functionality" as I do understand a/c systems for the most part as far as how they work and what to expect under certain conditions. I did question this operation though as it seems to be a new issue. I have a cycling compressor in everything else that I own right now (six other cars) and none of them, in the weather that we are in right now which is NOT that hot, are engaging in this behavior. It's only this car/system doing it. I understand that on a hot day, the compressor will run and run to keep the evap cold whereas on a cooler day, it comes on and within seconds is pressurized and the temps are down. I understand that there WILL be a change in vent temps when the compressor is on vs. off. What you say is everything that has gone through my mind already. I still, however, think there is something going on with this vehicle because I've been in it on a hotter day a while back when I first started observing this and it still warms and has erratic vent temps seemingly. I've been in it when it on a few occasions so far this season when the car has sat in the sun all day in ambients of 88-90 outside and it's still doing it.

As a matter of fact, I got in the car one day last week, started the engine (amb. outside around 85-88deg) and then engaged digital AUTO climate to MAX A/C....she started cooling fine and as I pulled from my neighborhood (stop sign at the main road) and accelerated, as the transaxle upshifted from 2nd - 3rd going down the road, the vent temps EASILY climbed into the mid 70's from whatever it had cooled it down to (prolly the 40's by that time) and then a few seconds later it started cooling again. There again, why is the compressor kicking out like this? This is NOT normal. It would NOT have been iced up withing the 1 minute drive from the driveway to the main road to where it was blowing hot, the compressor HAD to have kicked out to cause this.

Again, I agree with what you are saying but I've been working on cars all my life and to your credit, I am NOT an a/c expert. That is why I am here. I am, however, very well informed with what I know of them. I am MORE than sure there is SOME functional issue going on. Like I said in an earlier posting, I had a 1996 Pontiac Grand Am that, from a SYMPTOMS perspective, started doing this exact same thing. The major difference is that the Pontiac had a continuous running compressor system. When it started doing it, it was ALWAYS because the charge was low. I found that I had a TINY leak and when it started doing it, it was easier to adjust the charge than the time/cost etc. to repair. It would ICE you out at idle, but there was SOMETHING about driving the car and accelerating and shifting the automatic that would kick the compressor out. I defaulted to recalling that issue from several years past when this car did this, however, that is not my problem...hence me trying to understand a functional and scientific explanation for my issue that seems out of the norm to me other than to explain it with "normal functionality." I will continue to monitor, but dollars to doughnuts...something ain't right with this system and I'm going to find out what it is. I know the car VERY well and this is a new issue and this is NOT normal. I know normal.

I'm a few notches above the normal "scientific" people you probably deal with that have thermos in the vents ;-)

mk378 on Mon May 12, 2008 1:08 PM User is offline

Watch the low side pressure with an accurate gauge as it cycles. If the pressure is going much above the typical cut-in of about 45 psi, the cycling switch is a little balky and you could potentially get better temperatures by replacing it.

cmeseadoin on Mon May 12, 2008 1:13 PM User is offline

Makes excellent sence! I will try that but today it is raining and 45 here, LOL...go figure this EAST COAST weather! I know the problem has to be simple because the a/c works well and when that compressor IS ON, she's ice cold. The cycling switch should be in the accumulator at the firewall and is replaceable with a schrader under it so as to not have to evac and recharge to replace right?

Chick on Mon May 12, 2008 2:04 PM User is offlineView users profile

Yes, there is a shrader valve under the cycling switch, but as I stated above, I think recovering and recharging the exact amount back in would be a good idea since you have leaked some out. You don't want to have to change a compressor due to poor oil circulation...

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

GM Tech on Mon May 12, 2008 10:24 PM User is offline

The only other easy factors to shut down a compressor would be high pressure cut-offs (is high side behaving while driving? - run with gage set attached- could be inadvertantly overcharged)- or full throttle cut-outs-- some systems shut of a/c compressor at 87% throttle or so-- also there are load disablers-- if engine load is too high- or engine temperature goes too high then off goes the compressor...

......I once studied an Olds Aurora- there were 127 different ways to shut off the compressor- due to algorithm processes and PCM decisions---you need to have data capable scanner to determine if a/c request is present and if not- what sensor or condition is disabling the compressor

-------------------------
The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Edited: Tue May 13, 2008 at 8:49 AM by GM Tech

cmeseadoin on Tue May 13, 2008 9:14 AM User is offline

Yes, that is a very good point as well......This car is an electrical nightmare potentially. It is a VERY complicated car and was sort of ahead of it's time for 1994 if you know anything about it. Thoughts of being a PCM issue crossed my mind, but not sure 100% how to determine what might be doing it. I even thought that the transmission controller portion of the PCM might be somehow doing this and calling for compressor cut-out due to the issue seemingly being much more prevalent at speed and during acceleration than at idle sitting static. I have a fairly nice OBDII scanner....I will have to hook it up and go from a drive and see if I can monitor the A/C system and compressor status while driving. I have not been able to drive with A/C gauges on it either yet due to the weather. It WAS 85 and sunny, now it is 40 deg. and overcast, LOL. I thought even about making a long wiring test harness for my cut out switch and then high pressure switch and run contant voltage and continuity tests across the circuit while driving to see if when the air warms, at what point electrically the compressor is being triggered to disengage. Obviously, if the PCM is triggering the compressor cycle out for some reason, the end result would been seen by some downstream electrical circuit such as the clutch relay. Diagnosis of what PCM data is causing it could be difficult. Figuring the WOT or high throttle sensing system might be the culprit, I took the car out and just light footed it through the gears and it still does it. If I mash it harder there is really no difference noticable. I thought maybe the TPS was perhaps bad. I am not sure how the vehicle's load index is computed by the PCM? That would speak to the load % causing it.

First thing I will do is drive the car with gauges, watch the low side pressure in conjunction with the vent temps warming and then see if the cycle switch could be bad or starting to become flakey. Then if that seems to be working by design, I will start looking elsewhere. If it is the computer doing it, god help me! LOL Thanks, that is good info!

Those Old's Auroras are highly tweaked electrically too from what I understand. They are also NEAT cars though, especially if you have the V8....pretty quick considering it's size and weight. I like this SHO, even though she's a potential disaster, my father bought it new in 1994 and then gave it to me 6 months ago or so. It's about in perfect condition. She's just going to have a few issues as she ages, most of them were not taken care of and are in the bone yard by now. It is neat to have a close to mint example that's far from the bone yard.

cmeseadoin on Tue May 13, 2008 9:17 AM User is offline

Oh yes, maybe I was not clear......since all of this work and fiddling with it, I have fully recovered, vacuumed and recharged it to OEM 2lb of R134A :-)

On the first chance I get a descent day with good ambient temps for testing, I'll go for a drive and post my pressures and findings. I also am going to monitor that compressor and try to find the trigger causing it to cycle with more time inbetween cycles causing air temp warm up.

cmeseadoin on Tue May 13, 2008 1:49 PM User is offline

Here is a question.....if i wanted to jump the cycle switch so that I know that circuit is calling for the compressor to be on all the time, would it do any damage to go on a short drive with the compressor running the whole time to see if the compressor still cycles out causing the air warm up? I have a high pressure switch, so I am assuming that before I'd blow the refrig. charge out of the blow off valve of the compressor, the high pressure switch would kill the compressor before that would happen?

cmeseadoin on Tue May 13, 2008 4:30 PM User is offline

Ok, here is what I have.....Today it is around 70-73 ambient outside..came home from work and wanted to test my cycling switch. I hooked up my gauges and disconnected the two wire connector from the cycling switch on the accumulator against the passenger firewall. I know I could have just noted the pressures that she cycled at, but wanted to make SURE that what I was testing was the cycling switch killing the compressor. I disconnected the harness and checked for voltage with the a/c on...of course only one side was hot. I then knew that circuit closed meant compressor on, circuit open meant compressor off. I put a jumper in place and the clutch engaged. She started cooling and I ran it for a few minutes and held it at above 2K rpm to ensure no kick out. It ran continuously and my low side lines of the accumulator decided to frost, which was reasonable. I then put a continuity test across both terminals of the switch. I isolated at exactly what pressures she was continuous, meaning compressor needed to come on, and what pressure it was open circuited calling for clutch disengagement. I determined the following:

Clutch engagement: 44
Clutch disengaged: 21

This was the case every time with the continuity test. I then reinstalled my harness to see if the cycle times of the compressor now matched with what I knew the switch was calling for and they were right on. IF 44psi is an acceptable cut in pressure, it seems I am working as designed with the CYCLING switch only. I still could have some other variable altering the status of that circuit from being closed to open at the computer thus disengaging the compressor.

These are rough pressures with blower on one notch below full blast....this was also after it had run for a while doing all my testing so the vents were cool already due to cool air being circulated in them for a while.....rough because as the system runs, the pressures change:

IDLING as I did not hook up my OBDII so I could hit 2K rpm.....
HIGH at IDLE: 168
LOW at IDLE: 22.5
Did not measure vent temps but easily in the mid 30's

From here there are two questions for myself.....if there is NOTHING technically wrong here, is there a cycling switch that I can install that will trigger clutch engagement at a LOWER pressure than 44 allowing not as great of an air temp warm up?, and if there still might be some other factor causing clutch disengagement, thus air vent temp increase, other than refrig. charge and cycling switch, what is the next step?

cmeseadoin on Tue May 13, 2008 4:38 PM User is offline

I might add that the reason I am so fixated on this cycling switch and the pressures she comes on and off at is that this warm up issue is present at idle as well when measuring vent temps. I am not so sure that driving has anything to do with it as I gather more and more data here. The thing about idling is that when first turned on, the compressor has to run and run and run to cool off the interior and the duct work. So if you start it hot and crank up the a/c, she cools seemlessly and the vent temps are a steady decrease. It's once you've gotten it cooled down, run it for a while and everything has chilled...you can let it sit there at idle and observe this same vent temp warm warm warm then cool cool cool effect going on that I get while driving, as the compressor cycles. It is nothing more than the compressor NOT being on at a said low pressure. Is 44psi perhaps too high and would a new switch have a lower kick in? I'm starting to think there is nothing wrong here other than maybe I could improve efficiency with another type of low pressure cycling switch??? Any thoughts...I know I type alot but this stuff interests me and I am trying to be very detail oriented. :-D

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