I've been reading for a week or so about how AC systems work and problems they could have. One consistent thing I've read is to check how the compressor clutch reacts when you turn on AC - if it disengages then it doesn't have enough pressure and likely has a refrigerant leak.

My 94 Cherokee (apparently not great AC systems to begin with) seems to be blowing only slightly cool air when AC is on max settings. However, my clutch seems to be running fine. It never disengages or stutters even for a second. Aside from refrigerant leak, what are some other reasons why an AC system would not be producing much cold air?

I figure I'd ask here before I bought some UV dye to try to track down a leak.

3 Answers 3


If we're ruling out the possibility of a leak in the system and you're still not getting cold air then it's probably due to normal wear/age.

The refrigerant system is supposed to be a sealed system, but this is rarely perfect. If the AC system has never been serviced or it's been many years (6+) since it has been you could be just experiencing normal leakage. Cars are exposed to road vibrations, temperature extremes, and just time. Due to this the seals on the system breakdown slowly. The refrigerant will leak away very slowly and air will be introduced in to the system. You'll continue to have good enough pressure so the clutch engages but not enough to cool the car.

Rebuilding the system should make it like new and give you a good 10 - 15 years of life out of it. There's a cost/benefit of rebuilding the system vs a periodic vacuum & recharge.

If memory serves me correctly 1994 would have been within the range of when cars were switching from r12 to r134a. My experience is that the first cars to come with r134a had very poor AC cooling in comparison to earlier cars or current cars.

  • Thanks for the info. I'll get a recharge kit and see how long that lasts. This jeep has at least 10-15 years left on it (or more), so if the recharge doesn't last more than a couple years I'll probably opt for a rebuild.
    – Jerreck
    Commented Jul 16, 2015 at 20:32

The problem is the system is low on refrigerant. Since the clutch engages, there is enough refrigerant in the system (pressure) for the clutch to engage. If there wasn't enough in the system, it wouldn't even do that. If the system were where it is supposed to be, the compressor would kick on/off constantly once the system has been run for a little while. This happens after the pressures get to where they need to be on each side of the system (high/low). Since it is running all the time, the system pressures never gets to where they're supposed to be for the compressor to kick off, so it continues to run. This is also why you are only getting lukewarm air.

That your system has that many years on it is pretty common that some of the refrigerant has bled off. More than likely a recharge of the system with new refrigerant which includes a stop leak will probably keep the system golden for another five years. I wouldn't give up on your system yet, as there is probably still plenty of life left in it.


I would NOT use refrigerant that has ANY stop leak in it. It is VERY BAD for a/c systems. Over time, the stop leak could clog up condensers and/or compressors...eventually destroying them. If you have a leak or leaks, find it/them and fix it properly. Then go about evacuating and re-charging the system properly.

  • While that's good advice, this doesn't really answer the question. He never mentions adding refrigerant with stop leak.
    – Spivonious
    Commented Jun 6, 2018 at 20:04

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