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Yesterday the owner brought in his 04 Jeep Grand Cherokee Limited with a 4.7L vin N engine. It has automatic temperature control and the issue is that on hot days (90degrees and above) the AC will cool for awhile then quit. No air comes out the duct. They can wait say 20 minutes, turn on the AC and it works for awhile again till air stops blowing. That is the only symptom provided to me when they brought it in and said that it only happens on real hot days. I connected my pressure gauges and scan tool. Pressures are 28-32 on the low side and 220-240 on the high side at 75 degrees ambient temp yesterday. The compressor clutch cycles normally and the radiator/condensor cooling fan works on high and low speed. I am thinking it may be that the evaporator is freezing up. What do others think?

Tough to say. Id wait tell it happens and see what its doing. could be temp control unit the idea that the air quits blowing all together make me wanna look at the doors. control unit etc.

Have you checked for codes?

Sounds like evaporator freeze-up.

sbebenelli wrote:Have you checked for codes?

Forgot to mention that. No codes when I checked. Thanks for asking.

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excessive airgap at the clutch. Gets hot, coil wont hold the clutch in. Cools down works ok. I think that compressor has a spacer in betwween the clutch and the shaft. Take it out and see what happens.

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brother bubba wrote:...

excessive airgap at the clutch. Gets hot, coil wont hold the clutch in. Cools down works ok. I think that compressor has a spacer in betwween the clutch and the shaft. Take it out and see what happens.

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Would that make air stop coming out the ducts inside vehicle?

I don't think so. If the fan is still blowing but there is no air movement, freeze up is possible. Get a borescope and look in there, or watch for the stoppage of the condensate drip. Then let it sit and see if it starts dripping again.

Tim Martin wrote:

brother bubba wrote:...

excessive airgap at the clutch. Gets hot, coil wont hold the clutch in. Cools down works ok. I think that compressor has a spacer in betwween the clutch and the shaft. Take it out and see what happens.

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Would that make air stop coming out the ducts inside vehicle?

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Oops. Didn't read the first post close enough .........

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My interpretation of what has been said so far leads me to the blower motor or motor controls. When the air quits flowing can the fan still be heard or does it go silent??

I've seen a lot of evap freeze ups. Usually find them loaded with leaf debris or mouse nest padding.

steven kiser wrote:I've seen a lot of evap freeze ups. Usually find them loaded with leaf debris or mouse nest padding.

Well a cabin filter is supposed to keep that kind of stuff out of the evaporator, not?

Some jeeps may not have them from the factory while others i've seen the slot empty or so contaminated it collapses.

steven kiser wrote:Some jeeps may not have them from the factory while others i've seen the slot empty or so contaminated it collapses.

Well Steve, I very naively assumed an 04 Jeep would have a cabin air filter. I'll have to look when I get it back in.

I don't think the Jeep came with one, but you can add one in the cowl if you want.