AC recently fixed, now it drives weird :(

[pieter3d]

I just had my AC repaired. When I bought my 91 SHO ( http://dropman.com/pictures/pics/IMG_0017.jpg ), two years ago, the AC had no freon, it just blew warm air. Now it's been recharged and all leaks fixed, and works. I needed this since I am moving to Arizona.

However when driving with the climate control in auto mode, the compressor turns on and off at 5 second intervals. I can hear this happening and also feel it, it accelerates and decelerates with the compressor goes off and on. This happened when it was cold outside and I had it set to 70F. It makes the car the right temp, but drivingg like that is pretty damn annoying. The repair guy told me that was normal, which I don't believe.
So I ask the SHO masses, is it really normal?

 

[spazmoid]

Mine does the same thing, and it even makes an annoying clicking sound that makes my car sound like a piece of crap. It would be nice to find an easy fix.

 

[SHOtimer]

Cycling that often is not normal. The problem is either a low charge, or a large clutch gap. You should check the charge and make sure that it is where it is supposed to be. If it is not, refill it and your problem should go away. If not, you can adjust the clutch like this:

http://www.shotimes.com/php-bin/mod...e=article&mode=thread&order=0&thold=0&sid=143

Doug

 

[Mr Anonymous]

Cycling that often is not normal. The problem is either a low charge, or a large clutch gap. You should check the charge and make sure that it is where it is supposed to be. If it is not, refill it and your problem should go away. If not, you can adjust the clutch like this:

http://www.shotimes.com/php-bin/mod...e=article&mode=thread&order=0&thold=0&sid=143

Doug

This information is spot-on. Also, the PCM compensates for the drag on the motor caused by A/C clutch engagement by giving the motor a few add'l RPMs. Naturally with the short-cycling of the compressor, this probably seems a lot more noticeable.

Oh, and your A/C compressor will cycle in any climate control setting except OFF, FLOOR, and VENT when the ambient temp is above ~40 degrees.

 

[pieter3d]

Yeah ok, the repair shop had fixed all leaks and converted over to R134 (i think). I brought it in today ******** about the cycling, and the did some adjustments and it seems to be better now. Hopefully all leaks are gone now. This was damn expensive , they complained about how the fittings near the firewall are impossible to remove without rocking the engine forward etc... All I can do is take their word for it, I'm not much of mechanic.

 

[SHO_Diehard]

when driving with the climate control in auto mode, the compressor turns on and off at 5 second intervals. I can hear this happening and also feel it, it accelerates and decelerates with the compressor goes off and on. This happened when it was cold outside and I had it set to 70F. It makes the car the right temp, but drivingg like that is pretty damn annoying. The repair guy told me that was normal, which I don't believe.

One of my three SHOs does that, the other two don’t. The car that does it had the compressor replaced under warranty when the car had less than 36k (PO). That car surges when the compressor cycles seems to have a higher startup torque for the A/C compressor. The other two are probably cycling, but it’s not noticeable when driving. So, I don’t think it’s normal if it’s very noticeable. 5 seconds sounds too frequent also, could be low on freon as previously stated.

My car that surges has been doing it for the last 80k, I’ve never tried to fix it because it doesn’t do it all the time, just under low load conditions.

Yeah ok, the repair shop had fixed all leaks and converted over to R134 (i think). I brought it in today ******** about the cycling, and the did some adjustments and it seems to be better now. Hopefully all leaks are gone now. This was damn expensive , they complained about how the fittings near the firewall are impossible to remove without rocking the engine forward etc... All I can do is take their word for it, I'm not much of mechanic.

The fittings next to the firewall gave me a bunch of trouble.

You can learn to do your own A/C work if you are mechanically inclined. I think my set of gauges cost less than $100. Autozone rents the vacuum pump for just the deposit.

You should check out the posts on variable orifice valve to replace the fixed orifice tube the factory uses. You may need the extra cooling.

 

[pieter3d]

Wel the mechanic did some tuning and it worked. Now I have anew problem, aarggh.
The clutch sometimes doesn't engage. My mechanic jabbed at it with a rod while it was suposed to be on and it engaged. He seemed to want to replace the whole clutch assembly, but I read here somewhere that you can just reduce the spacing?
Also, he said that to work on it, the whole compressor has come come out of the car which racks up the labor. Is that true, or is removing the battery & tray enough?

 

[shojuan]

No, the compressor does not need to come out to replace the clutch. Just unbolted and moved a bit. Reshimming an old clutch can fix clutch problems if the clutch surface isn't worn too bad (not likely) and the coil is still good (more likely). However even a successful reshimming won't last as long as a new clutch assembly unless the existing clutch is in "as new" shape (yeah right). IMHO, it was a fair decision for the mechanic to replace the clutch assembly. Aftermarket assemblies are a good deal at ~$80 or so. Definately worthwhile to spend the extra if you are paying for the labor or are doing the labor yourself and you value your time. Reshimming the old part is good for somebody who wan't to try to fix the problem at no cost other than DIY labor.

 

[SHO_Driver]

I agree with Rick on that one. Also when I replaced the ac clutch I had the MTX out and the subframe for other work, yet it was a real pain to get access to the compressor face. I had to lift the engine pretty high to get access. Keep in mind I didn't unbolt the compressor at all.

 

[SHO_Diehard]

I'd Try Gapping the Clutch Myself

Concerning replacing the clutch or just gapping it, gapping it can work for quite a while. I bought our '95 ATX when it had 82k and it had too much air gap. I used the malfunctioning A/C as a bargaining point with the dealer, bought the car, then drove it home and fixed the gap. It's still working great at 112k. Of course, results may vary. If you gap it yourself, it's worth a try. If you're paying a mechanic, it may be worth it to get the clutch changed. Get estimates both ways, then decide.

 

[pieter3d]

I was quoted 300-400 including clutch & labor