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SpeakersGoBoom
10-04-2004, 10:58 PM
My Trans am has a problem with heating up. at idle, it just keeps going up and up and up...scary fast. I pulled into a parkway rest stop over the summer to put my t-tops back on quick, and when i got back in the car, my car was at over 260, and the coolant was boiling out of the tank. Anyway, I found that when the car is getting hot, turning the heat on full blast helps take away some of the heat, but what I found interesting is that when the AC is on, as long as the car isnt already running hot, the AC helps keep the car from heating up. I was stuck in traffic trying to get to jersey gardens the week of the Republican Convention (bumper to bumper going nowhere) and I was freaking out thinking my car was going to get too hot, but the ac really kept it down. it did rise, but only by maybe 20 degrees over the course of probably sitting in traffic for an hour. Can anyone offer an explination as to why the AC helps keep the engine cool? Thanks.

Pat
10-04-2004, 11:02 PM
turning on the AC activates the second fan.

check your water pump...

SpeakersGoBoom
10-05-2004, 07:56 AM
the waterpump was replaced with the engine about 4k ago, and its oversized. According to the engine shop, its the largest water pump that would fit that motor. My dad refuses to believe that theres something wrong with the waterpump, but then again my dad also refused to believe that AC kept the heat down, and he also refused to believe that my mounts were finished. Can you give me a more specific idea of what I'm looking for with the water pump?

The Fixer
10-05-2004, 09:02 AM
turning on the AC activates the second fan.

check your water pump...

In his case, since it's a TBI car, turning on the AC energizes the only fan. If your car got to 260 without the fan turning on, there is something wrong with the primary switch. There's lots of tech info on the fans over at www.thirdgen.org if you've never checked it out. Turning on the AC just bypasses the primary switch, so it can draw air across the condensor and keep the compressor cool.

Anyway, you should check a few other things out. If the waterpump is new, you could have a bad thermostat or clogged radiator. How old is the radiator?

SpeakersGoBoom
10-05-2004, 03:39 PM
original radiator, but was boiled or steamcleaned (cant remember which, but i think it was boiled) when the new engine was put in.

The Fixer
10-05-2004, 08:19 PM
original radiator, but was boiled or steamcleaned (cant remember which, but i think it was boiled) when the new engine was put in.

Well, I'd check the fan operation first. Let the car idle in your driveway, and watch the temp and see if the fan turns on. If the fan kicks on when it's supposed to (around 220, I think) and the temp still climbs, then it's a problem with flow; clogged heater core, clogged radiator, or stuck thermostat. A 180* thermostat may help, instead of the stock 195*. If you wind up replacing the radiator, get a Modine 951. It's a single core aluminum rad. with plastic tanks; stock replacement for a late third-gen F-body. I think your car prolly still has the copper rad. in it.

BigAls87Z28
10-07-2004, 01:31 AM
Well, your fan switch seems to be faulty, and its time to change it.

Also, I suggest you try and clean out the crap that builds up between the radiator and the support. Improving flow to the radiator makes a big difference.
Turning on the heater helps cooling because now there is more coolant going around helping remove heat.
Turning on the AC automaticly turns on the fan due to load put on the engine when the AC is on.

I suggest you replace your fan switch with an aftermarket one from hypertech or something like that. Also, GM sells a 170* stat that you can pick up at any GM dealership's parts room, and its cheaper then the ones you get out of Jegs or Summit.

Third Gens are known for the overheating. I had a 170 stat, and cleaned the crap infront of the radiator, and it stays at a nice 220, and then I am still scared.

Tru2Chevy
10-07-2004, 09:58 AM
Also, GM sells a 170* stat that you can pick up at any GM dealership's parts room, and its cheaper then the ones you get out of Jegs or Summit.

Why bother to order a stat for a SBC? Just go to autozone or advance auto parts and pick up a 160 or 180 degree stant thermostat for $3.95 like I did :)

- Justin

foff667
10-07-2004, 10:43 AM
:stupid::stupid::stupid: everyone is pretty much right on this one...get the tstat from autozone er wherever, and check the fan, make sure its comin on properly.

ar0ck
10-07-2004, 11:33 AM
A/C makes the engine run hotter.

Heater On makes the engine cooler.

foff667
10-07-2004, 12:13 PM
A/C makes the engine run hotter.

Heater On makes the engine cooler.

yes and no...on both accounts....when you turn the a/c on especially on cars with 2 fans the second of the two fans normally will come on helping to lower the temps, however because your running another accessory off of hte crank the engine stresses more and creates more heat so the usually equal out...turning the heater on as far as i know just blows air over the heater core which is basiclaly a mini radiator so again cooling little mini radiator can help sometimes.