My A/C has a mind of its own.

[Tim OLeary]

From when I bought the ST (a long time ago but used) the A/C worked fine.
Then recently it quit.
I took it to the shop and they say they repaired it. I thought it was fixed, but it will suddenly stop blowing cold air. I took it back and they said the A/C worked OK. They had the car running with the A/C on and it was working.
But when I'm driving it, the A/C still just stops working. The temp control doesn't seem to have any effect on it even when it is working. It's a new compressor, and the lines are sealed and correctly pressurized, I am sure, but the A/C works intermittently, and when it stops it starts blowing hot air. It's Florida here, so I am not sure if it is heated air or just outside air pumping in. Problem does not improve on any setting.
Before it crapped out, I left it on MAX A/C and that's where I leave it now.
Sort of disappointed with the shop, but they don't do well with intermittant problems just stuff that's "zero stop" broken.
Please help

 

[Tim OLeary]

It's a 2002 4D 4WD

 

[EddieS'04]

Are they taking the Trac for a drive. Or just garage testing?
It could be a vacuum issue with the direction door. Allowing hot air from the out side, or mixing the heat with it the AC.

 

[Evox]

Compressor clutches that are about to fail can be intermittent. At least that's been my experience. I still have the original compressor, but in 17 years, I've had to replace one compressor clutch, and before it completely crapped the bed, it behaved like that. Sometimes the serpentine belt grabs the right way, and they'll run. And other times, they won't.

 

[Ed Fenwick]

Mine is a 2002 2WD. If I slow down the compressor may not reengage. Then if I stop and start again it cools fine. I pulled the relay and sprayed it with electrical contact cleaner. "worked well for about 2 weeks then back to the old problems. I have ordered a new relay so we shall see. I hope that it is not the clutch.
God bless Ed

 

[rdmallory]

Does it stop cooling or air stop blowing? If air stops blowing look for vacuum leak. Canister is located under air filter.

Doug

 

[Greg Gibbs]

I lived with the same issue for years with my 2002 ST with original compressor. Multiple shops couldn’t diagnose it. Then, I saw a YouTube video about compressor clutches slipping and how you can remove a spacer (essentially a metal washer) to reduce the clutch gap so that it doesn’t slip. Bought a tool to remove the clutch, removed one spacer, put it back together, and it worked great after that. 10 minute fix!

Ideally, you should check the clutch gap and make sure it is in spec (before or after you remove spacers).

Here’s a link to a video that might help. I couldn’t get the clutch to lock, so I used a special tool to hold the clutch in place while removing the nut.

 

[Larry Holmes]

From when I bought the ST (a long time ago but used) the A/C worked fine.
Then recently it quit.
I took it to the shop and they say they repaired it. I thought it was fixed, but it will suddenly stop blowing cold air. I took it back and they said the A/C worked OK. They had the car running with the A/C on and it was working.
But when I'm driving it, the A/C still just stops working. The temp control doesn't seem to have any effect on it even when it is working. It's a new compressor, and the lines are sealed and correctly pressurized, I am sure, but the A/C works intermittently, and when it stops it starts blowing hot air. It's Florida here, so I am not sure if it is heated air or just outside air pumping in. Problem does not improve on any setting.
Before it crapped out, I left it on MAX A/C and that's where I leave it now.
Sort of disappointed with the shop, but they don't do well with intermittant problems just stuff that's "zero stop" broken.
Please help

I recently had a problem just like this. Worked great in town but not cold at highway speeds. The shop found a failing compressor clutch was the culprit and replaced with the compressor along with it as is their practice, along with all associated valves and parts. The original was never serviced until it quit at 154K miles.

 

[Harold Knutzak]

I have owned a 2002 2wd for about a year here in So. Central Florida. Used to brag about how cold and hard that a/c would blow. Around a month ago I noticed that on A/C Max it would only blow for about 2 miles then warm air. If I shut down the motor, went into a store, it would work again...for about another 2 miles. After experimenting I discovered that on normal A/C it worked fine. I have no idea what it is but it stays cool enough for me and the dog. Any input would be appreciated.
Oh, BTW, I always shut off A/C and fan BEFORE shutting off engine and start engine before starting up A/C. Don't know why..I think it was something my pop taught me many moons ago.

 

[Tim OLeary]

Thanks for the feedback. I think they are testing it without driving it.
I'll look up the compressor clutch idea.

When I first got the car back from the A/C repair, I tried several switch positions, and it seemed to me it only worked on the one where both the upper and lower were on.

After they gave it back to me the second time, it was on AC MAX and so I have kept it on that position.

Is the compressor clutch part of the compressor or a separate part?
Thanks again for the feedback.

 

[Evox]

Thanks for the feedback. I think they are testing it without driving it.
I'll look up the compressor clutch idea.

When I first got the car back from the A/C repair, I tried several switch positions, and it seemed to me it only worked on the one where both the upper and lower were on.

After they gave it back to me the second time, it was on AC MAX and so I have kept it on that position.

Is the compressor clutch part of the compressor or a separate part?
Thanks again for the feedback.

It's attached to the compressor, so I guess that makes it part of the compressor. But you can replace it. As I said, I've owned my '04 since new. It still has the original compressor in it. But I have had to replace the compressor clutch once. I guess 3 or so years ago now. I can't remember. But it's not hard.

 

[Tim OLeary]

I am assuming the whole compressor was replaced already.

When the AC stops blowing cold, it still keeps blowing.
I saw there is a damper control under the dash that seems to me might be the culprit?
Thanks for the feedback.

 

[Ed Fenwick]

rd Mallory, when it quits, it still blows warm. Sounds like the clutch to me. I can't find where I ordered the relay from. I will just go to NAPA and get one.
Greig, is there a min and max gap for the clutch? If I remove too many spacers will the clutch be always engaged or will it burn up?

 

[Greg Gibbs]

rd Mallory, when it quits, it still blows warm. Sounds like the clutch to me. I can't find where I ordered the relay from. I will just go to NAPA and get one.
Greig, is there a min and max gap for the clutch? If I remove too many spacers will the clutch be always engaged or will it burn up?

I don’t recall the gap specs, but the short answer is yes. If the gap is too big, the clutch won’t be able to engage fully and will slip. If the gap is too small, it may be engaged all the time so the compressor will run constantly which can cause damage. (It’s meant to cycle on and off.)

I knew my compressor worked because the A/C was cold most of the time. When it was really hot outside or I was idling in traffic, it would begin to blow hot, humid air. Over time, I took it to 3 different shops and they said it's working fine or they said added some refrigerant. I'm guessing many repair shops take advantage of people by telling them they need a new compressor when they only need to adjust or replace the clutch.

Here's a link to a site with some examples of the gap specs for various compressors. You'll see that many of them are similar or the same.
Adjust AC Compressor Clutch Air Gap

You may want to check to see if there are any spacers installed. Mine only had one in there, so I removed it. If the clutch slips in the future, it will have to be replaced since it can no longer be adjusted. (You can buy a clutch replacement kit pretty cheap.)

If yours has one or more spacers, you can remove one (or more) to achieve the proper gap. I used a set of feeler gauges to check the gap, but I've also seen a clutch gap tool. You’ll also need a clutch holding tool ($13 on Amazon) to hold it while removing the bolt.

If you want to do it yourself, just do some Google searches and watch some videos. Definitely watch that video I posted above to get a good idea of what you'll need to do. It will go something like this:

1. Once you know the proper air gap specs, measure the clutch air gap on your compressor. If it's too big, proceed.
2. Remove the serpentine belt to avoid damaging it.
3. Use the clutch holding tool to keep the clutch from spinning while you use a ratchet/wrench to remove the bolt on the front of the clutch.
4. Remove the clutch slowly and carefully check for spacers. (You want to know how many were in there.)
5. Remove one spacer (or more, as necessary) and put the rest back in there before reinstalling the clutch bolt to the proper torque spec (12 ft/lbs).
6. Check the air gap to ensure it is in spec. (Make more spacer adjustments, if necessary.)
7. Reinstall belt and test it out. Make sure the compressor cycles on and off. It may be hard to replicate the problem, so keep an eye on it as you drive on really hot days when the compressor is working harder.

Hope this helps!

 

[Ed Fenwick]

Mine is working now! I had to wait for a hot day and go for a drive. What I did was replace the relay. Give this a try if the clutch adjustment doesn't help.
Ed

 

[Tim OLeary]

Waiting for a hot day! Thank God now I'm in FL I don't have to wait long. I leave the settings alone and the A/C engages then stops, then engages, etc. There seems to be some confusion as to which relay it is. I'll figure it out (). I's worth a try. Thanks

 

[Daddattack]

I'm glad it seems like this is getting sorted out!

While reading through the post, I saw mention of an issue that drives me crazy, which is apparently a vacuum line somewhere not being fully sealed? I have to constantly fiddle with my vent direction switch to get A/C to blow on my face. Right now, the machine has decided that FLOOR=FACE but most of the time I luck out and get face A/C when I set it to defrost. I don't care turn my A/C off in fear that I won't be able to get it set properly again - and I live in Georgia so driving around without A/C in my face is a life I don't want to live.

 

[Ed Fenwick]

Rats, it isn't fixed yet! Yesterday, it quit on me. With the engine off and the key on, I hit it with a stick and the clutch engaged. Maybe I need to look at the spacers, dam. The relay is under the hood at the back of the relay box. There are two small relays. One is horn so you can tell which one you pulled.

 

[Harold Knutzak]

Rats, it isn't fixed yet! Yesterday, it quit on me. With the engine off and the key on, I hit it with a stick and the clutch engaged. Maybe I need to look at the spacers, dam. The relay is under the hood at the back of the relay box. There are two small relays. One is horn so you can tell which one you pulled.

I stopped by the shop I use yesterday. He came in on a Saturday especially for my A/C, knowing I was leaving on vacation next week. He drew down all the Freon and the refilled. Blew cold air like hell. Luckily (???) he was still in the truck with me when it stopped blowing cold and went into warm mode. I wasn't gonna make him work any longer on a Saturday as he didn't charge me in the first place. Looks like it's gonna be a warm drive next week.

 

[Tim OLeary]

Wow. Same mystery as with mine. My shop initially charged me the usual price for the compressor/service, and since then it has been back twice. First time they didn't charge me, but it still didn't work. Second time they didn't charge me either, but it was still intermittent. Every trip to the shop involves me leaving the truck and arranging a rides, them keeping the truck. I use the truck every day so it's inconvenient and not "free". Then when they say the AC works, it's insulting. I think intermittent problems are very hard to troubleshoot and A/C systems are difficult unless your a specialist. I always contact them so they know it's still the same issue they need to address, since if it's in the compressor, I am not paying for another one. If I changeshops for this repair and they say it is the compressor it will be challenging to get credit for the compressor. Thanks for the relay info! Stay frosty