Intermittant loss of A/C cooling, high idle

[cold_steel]

Ok here's an odd one- just wanted to know what you guys think. I was driving on a hot day about a month and a half to two months ago and I noticed my A/C started blowing a little warm, and at the same time the engine would idle noticibly higher with the clutch pressed in than normal. Funny part was if you turned the A/C off, the engine would immediately start idling normally. This seemed to be a one time thing but it has happened again a couple of times since then, but when the high idle behavior isn't happening, the A/C is blowing cold and normal. wth?

[Bob Ayers]

When the AC compressor engages, the PCM increases the idle speed with the IAC valve to compensate for the additional load of the compressor. It sounds like the clutch isn't engaging on your compressor when it's supposed to, and the idle speed is increasing because the compressor load isn't there....
Check the AC compressor clutch, and the wiring to it.

[cold_steel]

Makes sense... thanks! I'll have that checked into.

[cold_steel]

so- how difficult would it be for a relative novice to replace the clutch?

[cold_steel]

Ah crap. Pulled the clutch plate to have a look and found the part that catches in the compressor bright green with refridgerant leak detecting dye. Looks like I'll need a compressor = (

[Earl43P]

Compressor shaft seals all leak to some degree.

If it holds enough charge to get throught the cooling season, I'd let it ride.

Sounds like the leak got oil on the compressor clutch, making it not engage, intermittently.

http://www.autoacforum.com/messageview.cfm?catid=20&threadid=14950

[cold_steel]

It was about half out of r134, it was cooling but it wasnt making the tubes sweat like they were supposed to. If it was half low I'm guessing the leak is significant right?

[Earl43P]

Depends how long ago it was serviced.

My 93 needed about 4 ounces to make it frigid.

No idea when it was serviced last, since I just got it a couple months ago and just started driving it.

How did you determine it was 1/2 low? Unless you installed a set of gages, you can't tell. I'd put a thermometer in the center vent, run the engine at 2000 rpm, fan on med-lo, not in Max, and look at the outlet temperature.

Then add r-134a (under those same conditions) until the outlet temperature stops getting colder. Then drive it. If it gets 2-4 degrees colder when driving, call it good.


If you are "going by" the can/hose with a green/red gage, well....they are slightly better than guessing. But not by much. Use the thermometer method. More refrigerant isn't always better. If you put in too much, it won't cool + you risk overpressurizing and blowing a line.

[MAKG]

You should never blow a line due to overpressurizing. There is a pressure relief valve. However, you can greatly speed the demise of your compressor by making it work A LOT harder.