Air Conditioning help

[NotSoSlowSHO]

Okay guys and gals....

My fiance has begun hounding me to get the AC in the titanium fixed for our trip to the convention. Unfortunately, this is one area I am conpletely uneducated in. Ive never dealt with an AC system before, minus a quick R134 recharge.

Here's the scoop:

When I bought the car, the AC compressor power harness was unplugged at the compressor. I was told by the PO that the AC worked, and had been retrofitted for R134, but it needed a re-charge. Great, I said. It was winter at that time, I didnt need the AC, so I didnt look into it until later.

Months later, its getting warmer. (70+) So, remembering what the PO said, I plugged the compressor back in, and gave it a quick R134 charge. Pressures were in the GREEN on the recharge kit gauge. It worked, but BARELY. The compressor seemed to cycle normally (would engage for 5 seconds or so, then disengage). I put a thermometer in one of the vents and the lowest reading I ever got was 50 degrees (on a 70 degree day).

At the time, I was neck deep in graduate work and lost the time and the interest to get it working correctly. I assume Im dealing with a leak (its ONLY 16 years old ) but I also figure Im dealing with something else?

Could sombody outline a sequence of actions I should take to get this system back in working order?

Any help would be greatly appreciated!

On a side note.... In my forum searching, I came accross a reference to a troubleshooting guide put together by "MELS" but have been unsuccessful in finding such a guide.

 

[SHO_Diehard]

The first thing IMO would be to get a set of gauges if you don't have them already. Do you have pressure on the system?

Apparently the system was converted to R-134a, otherwise you wouldn't have gotten R-134a in due to the fitting size. From what little I know, you need to watch out on adding oil to the system, the various oils are not necessarily compatible.

R12 = mineral oil
Factory R134a system = PAG oil
Conversion oil, work in either system = ester oil

Someone please correct me if that's wrong. I just asked one of the more knowledgeable guys at Autozone today and he didn't know.

I believe I read that the old R12 hoses do not hold R-134a that well. Not a problem if you recharge it yourself and only have to do that occasionally Not sure about the original o-rings.

If you don't have pressure on the system, rent a vacuum pump from Autozone and see if you can pull a vacuum.

I just got my A/C going in the '95 this afternoon. Three problems at once, excessive clutch gap, low freon, and bad pressure switch. Talk about Murphy's law!

 

[NotSoSlowSHO]

Thanks for the quick response

It has been retrofitted to use R134. And the only charge I have given it was one that also used ester oil.

I just got back from a local parts store (the ONLY one we have.... a Kragen with idiots behind the counter ).

I picked up the following:

A "leak finder kit" that includes a UV die charge, a pair of yellow goggles, a UV pen light, and a "seal conditioner/sealer charge". I also picked up a handful of AC specific O-rings. I couldnt make out exactly how many I might need reading thru the shop manual, so I grabbed all they had. Only 5

Hopefully this will get me on my way....
But before I can do anything, I need to throw the stock assesory belt.... I totally forgot that I bypassed the AC conmpressor months ago with a smaller belt!

 

[SHO_Diehard]

Thanks for the quick response

No problem!

It has been retrofitted to use R134. And the only charge I have given it was one that also used ester oil.

I picked up the following:

A "leak finder kit" that includes a UV die charge, a pair of yellow goggles, a UV pen light, and a "seal conditioner/sealer charge". I also picked up a handful of AC specific O-rings. I couldnt make out exactly how many I might need reading thru the shop manual, so I grabbed all they had. Only 5

Hopefully this will get me on my way....
But before I can do anything, I need to throw the stock assesory belt.... I totally forgot that I bypassed the AC conmpressor months ago with a smaller belt!

A seal conditioner charge I looked at today had PAG oil. Does your can? That might be a problem.

Do you have a vacuum pump or a gauge set?

Speaking of the belt, how is the clutch gap (part of the A/C pulley)? Should be 0.021-0.035 IIRC.

Do you have a Ford shop manual, it has a good troubleshooting chart.

 

[NotSoSlowSHO]

No problem!



A seal conditioner charge I looked at today had PAG oil. Does your can? That might be a problem.

Do you have a vacuum pump or a gauge set?

Speaking of the belt, how is the clutch gap (part of the A/C pulley)? Should be 0.021-0.035 IIRC.

Do you have a Ford shop manual, it has a good troubleshooting chart.

Well, I had to get off my lazy butt and go to the garage to check the can, but no, it doesnt have PAG oil. it is also ester. It also says " compatable with all factory equipped R134 systems as well as R12 systems retrofitted to R134. Contents are compatable with all R12 residues and equipment."

I have a single gauge set.

I havnt checked the gap on the clutch. Do you have to remove it to do so?

yep, I have the Ford shop manuals. Fat red ones.

 

[SHO_Driver]

Well right now does the system have pressure in it? Or has everything leaked out? If there's nothing left the next step would be to vacuum test it. That will tell you if its a small or large leak.

If you still have freon in there, try shorting the cycling switch then wacking the compressor with a broom handle or something.

 

[NotSoSlowSHO]

Well now Im stumped.

I put the old belt back on, plugged the harness into the compressor, and fired her up.

AC compressor clutch is cycling like normal

Keep in mind, that this system hasnt had a recharge for nearly 2 years.

I put a gauge on it, and it is cycling as it is supposed to. Low and high pressures during cycling are on par. It "clicks" to engage, holds for 5-8 seconds, then releases for 10 seconds or so, and repeats. Obviously it IS holding a charge and the compressor/clutch is functioning.

I also injected some of the leak detector die. No leaks

As for temps, the air blowing thru the registers is cool, but definately not COLD. I couldnt find my thermometer, but if I had to guess, Id guess it was only down to MAYBE 45 degrees. And it is just about 65 degress outside.

So I guess I should now try and get it to operate more efficiently??

Another thing, with the digital climate control in the '89 SHO, the lowest temp you can select is 60 degrees.

 

[SHO_Diehard]

I put a gauge on it, and it is cycling as it is supposed to. Low and high pressures during cycling are on par. It "clicks" to engage, holds for 5-8 seconds, then releases for 10 seconds or so, and repeats. Obviously it IS holding a charge and the compressor/clutch is functioning.

Hummm, I think that might be cycling too fast. The system pressure with the compressor not running must be about 30-50 psi, above the low pressure switch setting of around 20. The compressor starts, pulls the pressure down below 20 as it starts pressurizing the high side, then the compressor trips off on low pressure. I think my non-operating pressure is about 80. (I could be wrong here, if any experts are reading, please correct as necessary)

I also injected some of the leak detector die. No leaks

Could be you just slowly lost the R-134a through the hoses since they don't hold it as well as R-12. The rate of loss is going to decrease as the pressure gets lower, so it could sit there at a low pressure for some time.

As for temps, the air blowing thru the registers is cool, but definately not COLD. I couldnt find my thermometer, but if I had to guess, Id guess it was only down to MAYBE 45 degrees. And it is just about 65 degress outside.

So I guess I should now try and get it to operate more efficiently??

Yeah, looks like you might get off easy on this. I would throw some more R134a in there. Not sure what pressures you should be seeing at 65 deg F ambient, it was 85 here today and I saw 220 high/45 low. I would think it would get up to maybe 35 psi and hold steady without cycling.

Another thing, with the digital climate control in the '89 SHO, the lowest temp you can select is 60 degrees.

That's all the newer cars SHOw as well, even when you hit the max A/C button.

Can you check the high side with that gauge, or just the low side?

 

[SHOKYLE1]

If you got a 134 with sealer in it you may have a clog in your system. The sealer in that stuff reacts to moisture. is the inlet to your evaporator getting cold. the inlet and outlet of the evaporater should be very close to the same temperature.

 

[shospeed143]

First thing first you should not mess aroud with A/C systems if you do not know what you are doing. I would take it to a certifed shop and have them look it over. I have been certifed by both the EPA and the state of WI to work on A/C systems and know that if you get anything in your A/C system then you could damage the components in the A/C system. If you still want to work on A/C systems then i would go out and get a good manifod gauge set to connect to your car to see what the pressures are with the system running and i could tell you what you should look at if anything is wrong.

 

[SHOlocke]

go to harborfreight, get a good vacuum pump, and buy thier manifold gauges. They'll work well enough to do what you need to do. Pull a vac on your system for about an hour, really will work out your air compressor

Then take note of the gauge readings, both high and low side. leave the gauges hooked up for a full day of rhe car sitting in the garage, go mow the lawn, drink a beer, or do something for the whole day. Ok maybe drink more than A beer.

Look at the vacuum that night. if you held the same vac all the day, then chances are you don't have any leaks anywhere. you can then go on to proper filling of the system, which will involve you filling from the fully vacuumed out state, till you get to where the ford manual says. Course if you want super cold AC, you will need to fill up about 1/2 with r-134a, jumper the pressure switch on the dryer, run that for a while, then vacuum it all out again, then refill to the proper leve of r-134a.

Doing tht will get all the residual moisture that has boiled off from the air in the system out, and get you the coldest you can get without major changes to your system.

The most important part is the vacuum. YOU NEED TO DO THIS TO GET RID OF THE AIR AND WATERVAPOR in the system, or it will never get really cold.

I had my car blowing out 38F air the other day in 80F heat.

Course this can be costly but still far cheaper than paying someone else to do it. Don't worry about venting 134a into the atmosphere, heck buring the rubber out of you motor mounts causes more environtmental impact Just don;t breath the R-134a in, man that stuff will knock you out.

 

[shospeed143]

Just putting the system under a vacuum will not tell you if you have any leaks because when you put the system in a vacuum any small holes will close, but when the system is under pressure the holes will expand and the system will leak.

 

[djsSHO]

Just putting the system under a vacuum will not tell you if you have any leaks because when you put the system in a vacuum any small holes will close, but when the system is under pressure the holes will expand and the system will leak.

while partly true if you can't hold a vacuum you have a leak somewhere. the best way to find a leak is to charge system with ac dye and run the system for a few minutes. Then obtain a blacklight and a set of yellow glasses described earlier in the post and check hoses, compressor, condenser, etc. when you find your dye you have found your leak.

the gauges when the system has leveled out should be the same as ambient temperature. So if it's 73 out you should have about 73 psi on the low and high side with the vehicle off. It doesn't have to be exact but it should be close.


Cycle times should be closer to 1 minute on ...20 seconds or so off...if the air is really hot and humid you can run into a situation that it just keeps running and never cycles off. this is also a normal condition. The reason the system turns off is that if the low side gets too low of a pressure the lines can get too cold and freeze, thus creating problems. so the compressor cycles off for a bit to equalize pressure and warm up the line again...once it has reached a pressure around 40 psi it will cycle the compressor back on.

Hope this helps!

 

[SHO_Diehard]

I havnt checked the gap on the clutch. Do you have to remove it to do so?

No, you can check the gap, the clutch is open. The battery might be in the way.

yep, I have the Ford shop manuals. Fat red ones.

I haven't read mine very closely either. It's more exciting when you learn as you go

Anyway Kenny, are you confused yet with all these posts(J/K)? IMO, if you never lost pressure on the system, just adding freon may work. As was pointed out though, if you got some air in the system along the way, it will affect the performance, not to mention what any water would do. BTW, you should purge the charge hose with freon before charging into the A/C, otherwise you are putting some air in there. I accidentally did this with one of the hoses a couple of days ago on my project. Still felt nice and cool today, though not quite as good as the other '95 we have.

 

[HighSpeed]

the best way to find a leak is to charge system with ac dye and run the system for a few minutes. Hope this helps!

If you can't hold vacuum for a min of 15-30 mins, you have a leak.

You can also use a "sniffer" to find a leak.

 

[qiksho]

Kenny,

Shotimes has a good write up on how to check and change your a/c gap. I just finished re-gapping my 92 a few minutes ago because it was cycling to fast.

I have performed this clutch gap procedure on 3 out of the 4 SHO's I have owned now, so its not uncommon to have the gap out of spec.

I only had one shim, so I couldn't just take one out. I went to my local Ford dealer and he gave me 5 shims of different thickneses, which helped me get the gap back into the low end of spec at .022

 

[NotSoSlowSHO]

Thanks for the info.

Oddly enough, it seems to be working great now. And I didnt do a damn thing :corn: