AC blows cold air only when the outside temperatures are under eighty degrees

ISN M

MEMBER
2010 CHEVROLET TAHOE
5.3L
V8
2WD
AUTOMATIC
160,300 MILES

My AC only blows cold when the outside temperature is not hot. When outside temperature is 85 degrees or hotter, my AC blows warm air. Once outside temperature is under about 80 degrees, my AC starts blowing cold. Please help. Thanks, Ian

Thursday, June 6th, 2019 AT 6:55 AM

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Hi ISN M,

Have you checked the pressure for the high and low side of the system?

I attached a chart that will show pressure for each side at each ambient temp.

Let me know what your pressures are and we can go from there. If you do not have a gauge set then you can rent one from a parts store as they most have rental programs these days.

Have you attempted to charge the system recently?

Also, I am wondering if the evaporator is freezing when the compressor is running? Does the compressor ever cycle meaning does it cut on and off?

Let me know all this info and we can go from there. Thanks

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Thursday, June 6th, 2019 AT 7:47 PM

ISN M

MEMBER
2 POSTS

Thanks for your reply. Just want to let you know that I am working on this. I do not have the tools you mentioned. I'll be stopping at Advanced Auto or AutoZone for some assistance. I did try to recharge the system with AC Pro, about six months. It showed it was full. I'll do all you recommend and will report back to you.

I know the compressor does come on and off. Actually when I'm driving and I turn AC on for the first time, it makes kind of a whirring noise, but, it stops and blows cold for a bit then blows warm/cool.

Thanks again. I'll let you know what I find out,

Ian
I typed my name incorrectly during registration.

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Thursday, June 13th, 2019 AT 1:18 PM

KASEKENNY