Mechanics

AC BLOWS COLD THEN WARM

2000 Isuzu Trooper • 6 cylinder 4WD Automatic • 187,000 miles

My 2000 Isuzu Trooper AC blows cold for about 15 to 20 minutes and then it will start blowing warm after, need to turn OFF the switch (on dashboard) for about 3 to 5 minutes and then turn it ON before it will start blowing cold air again, this happens during outside temperature is hot. (It seldom happens during morning when the temp is still low) I already replaced the high pressure switch (dryer), thermostat, expansion valve, had the evaporator cleaned/serviced, found no leaks, freon is Ok and also changed the serpentine belt. I replaced the compressor clutch just almost 2 years ago. What might be the problem?
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Adrian315
July 27, 2011.



You have to first of all duplicate the problem, look to see if clutch is engaged when happening, if it is then suspect system is freezing up, if drier has not been changed then replace and let sit on evac for at least 1 hour and check for leaks, if not engaged then have to trace down loss of power or ground at clutch.

Raiderron
Jul 27, 2011.
Thanks for the response. Been observing the car for the past few days, pulling over everytime it blows warm air, noticed that the condenser fan (just replaced recently)isn't moving and compressor clutch is not engaged, I just find it hard to believe that my Ac clutch is already done knowing that I just changed it almost 2 years ago, (1 year and 10 months to be exact) in which the mechanic told me that it is that's causing the problem. I read from some threads/topics that an Ac clutch has a shim and sometimes it can cause the clutch not to function/engage well depending on the wear that it has. I checked the diagram of my car's compressor/clutch and saw that there is a shim on it, do you guys think that this might also have something to do with the this kind of problem? Also, the big question that really boggles me is, how is it that the problem only takes place during the outside temp is hot.

Tiny
Adrian315
Jul 27, 2011.
The clutch will engage more and work more the hotter the system is based off of ambient temp. Sensors read inside temp and react accordingly. The shim that is in there may be the wrong thickness and when the clutch is worked repeatedly the prob gets worse. Measure the air gap and compare to spec to see if gap is correct between back of clutch and the pulley front. There should have been multiple shims in the clutch kit that allows you to measure with feeler gauge and set to spec. Or you have a switch/sensor that is interrupting the power to clutch and fan at intermittent times.

Raiderron
Jul 27, 2011.
I'm not even sure if the thickness of shim is wrong, I have the whole clutch replaced when the bearing (or whatever that is that made a squeaking sound) first broke off, the replacement part is genuine and came from the dealer, that's why I just can't accept that it only lasted for. Say 2 years, (now im whining), I know there's nothing I could do, how long does it supposed to last by the way? Im now more inclined to believe that it's probably the shim since I already norrowed down almost everything else.
Thanks for your inputs, much appreciated. Gonna bring the car to the mechanic tomorrow and tell all what you've said.

Tiny
Adrian315
Jul 28, 2011.
Let me know how it goes.

Raiderron
Jul 29, 2011.