AC and coolant temp acting up

[shrek77]

Ok, this is a strange one. Today it was about 80F outside and I tried using the ac for the first time in the city. After a couple minutes stopped at a red light the ac would blow warm and you could feel the pump turn on off every 5 seconds or so. Then I noticed the temp gauge was going up. It went almost to the second line after 210. I would say a about 230. When the light turned green and I would travel a couple minutes it would go back down and the AC would be cold again also. I traveled about 10 minutes and pulled over and checked the fan and the coolant level. The temp went back up as I sat there with the ac on and the ac pump turning on and off. I was able to stop the fan with my leather wallet pretty easily, no resistance. After shutting the ac off, after a couple minutes the temp went back to normal. I drove across town to eat and after leaving the restaurant the ac worked fine, stayed cold at every stoplight and the pump stayed on as far as I could tell. went to a friends house and let it run for almost 10 minutes with the ac on and the temp didn't move above normal and it stayed cold the entire time. The coolant level is good, had the water pump replaced last week, t-stat replaced in February. The ac and recirculation were both on. Have only had the T-blazer since end of January. I tried researching but found nothing with both scenarios combined. Hopefully I was detailed enough for someone to help, or has had this happen to them. Thanks for any input I'm stumped!

 

[Sparky]

It is fairly typical for the AC to not be as cold at idle as when driving, but the engine temp going up is a little odd

 

[Ace1875]

When did you replace the fan clutch?

 

[shrek77]

The ac was warm like outside air temp when it occurred, and I don't know if the fan clutch was ever replaced. The fan runs in the morning when I first start it, It roars for a few seconds. And no check engine light either.

 

[AbsoluteZero]

The first fan clutch on my 03 Envoy would turn so slowly at idle you could count the fan blades. Without much air moving thru the radiator the compressor would shut off because of high head pressure and the ac discharge temperature would become warm. I don't recall the time interval but after the system's pressure reduced to under the head pressure high limit the system would restart and the recycle repeated. Any forward movement of the vehicle would move enough air thru the radiator the system worked fine. A new fan clutch was replaced under warranty. I can't explain why you problem is intermittant..... when the discharge temperature is warm and the engine temp is rising you might verify what the fan is doing.

 

[shrek77]

The fan was spinning pretty fast when this was occurring, it took several seconds for me to stop it with my wallet. I read online last night and found that if the ac is too full it can give an some issues but only doing it that period of time is strange. Maybe it was filled up before I bought it, and it's border line almost overfull. I know they mounted a tranny cooler on my radiator when they replaced the tranny, I don't know if that can effect anything. I'm going to spray out the radiator at the car wash when I wash her next time. It is supposed to be in the 80's today so I'll use the ac again today and see if it happens again. Thanks for the input I appreciate the help everyone

 

[shrek77]

Yesterday it was near 90 outside. I drove around in the city with the ac on the whole time I was out and there were no issues. Stayed cool no matter how long I had to sit in traffic, and the temp gauge didn't go up above the normal 210. Not sure what caused the issues the other day but hopefully it was just a glitch in the system.

 

[Sparky]

Very well could have been. Or maybe you had a little goo in your radiator - how long has it been since you had a coolant change or flush?