TMDZ28

can a bad radiator cap causes the temp. to rise up slowly?? just wondering if that's the cause of my rising temp when i turn my AC on....

thanks

madwolf

The system won't be properly pressurized if the cap isn't good. This may lead to overheating issues, but I really don't see why not just replace it? I mean, it's like a $3 part...

Compstall

It's fairly normal for the engine temp to rise a little with the A/C on due to the load.

If your cap is bad, that can also cause overheating. If your cap is original, it wouldn't hurt to change it out, they're pretty cheap.

96speed

If the cap is not keeping adequate pressure on the coolant, its going to let coolant into the overflow tank. This one reason you should replace a faulty coolant level sensor and not just unplug it. If you keep topping coolant off and it never levels off and you know its not a headgasket or leak, its likely the cap!

Ryan

TMDZ28

thanks for the info.....

i will replace it today. also my low coolant sensor is bad too, it lights off sometimes, but i always check my coolant level, and it always full.....

Z28SORR

Wrong, for LT1's. In hot climates turning the AC on turn both fans on and the temps. go down not up.

Compstall

I've had my car long enough to know how it runs. It typically goes up 10-15 degrees.

TobyZ28

AC takes my car temps down. Turns the fans on sooner in traffic... keeps temp around the 1/4 mark.

ut

If you have AutoZone out there you can borrow a cap and radiator pressure tester.

TMDZ28

that's what happen before my waterpump took a dump on me. i replace the waterpump, and reprogram my cooling temp to 185* and BoOm.... now as soon as the AC's on. the temp is crawling up....

what do i have to do???

the temp. rising with the AC on never happen before. usually, as soon as i turn on the AC, the temp goes down to 1/4 mark. but now, it's creeping up slowly.....

maybe i need to reprogram my fans not to shut off untill i reached the speed of 45 MPH

gb95zconv

Im with Brent on this one....my temp goes up 10-20* when the ac is on...now befor I started using the 160* tstat and reprogramed the fans the reverse was true.

G22Lvr

You guys that are having this problem have other issues in your cooling system if this is truly what is happening. I found out when mine was doing it that I needed to do a heater core flush. Since the flush, my temp goes down, and stays steady.

JSK333

My temp goes up too when the A/C is on. And when it's not, my car runs cool.

I checked with a logger, and you can see that the A/C adds load onto the engine. Just at idle it'll go from ~30kpa to about 38-39kpa. That will make the engine run hotter, no doubt, even if the fans come on.

Z28max

Mine stays at about the 1/4 mark as well with AC on, if I turn it off the temp goes to about 1/2, more if I'm in traffic.

96redformula7

My radiator cap lost complete pressure within 5 seconds on the cap tester and it DID CAUSE A HIGHER TEMPERATURE!! I put on a new cap and like everyone else now with 160 t-stat, watter wetter, new radiator and waterpump, I usually do not pass the 185 mark unless I turn the car off, back on, then off again, then back on. I wish i had replaced the cap before I did all that stuff though, andyes the temp should be slightly higher with the ac on, cause it will send heat into the engine bay.