What type of sensor could be malfunctioning if I have to drive with either the heat or air conditioning on? Otherwise the engine will overheat.

Asked by Sep 06, 2013 at 12:20 PM about the 2005 Pontiac Grand Prix GTP

Question type: Maintenance & Repair

Radiator and thermostat replaced, no leaks or air in the system, Fans work. Any
suggestions?

8 Answers

254,045

Sounds like a low flow problem. How old is your water pump? Maybe a blockage, but you replaced the radiator, hoses and flushed the system already, right?

100,275

To your knowledge was any stop leak used in the cooling system, if there was it may have plugged up some of the smaller coolant passages. If you did do a flush was it a back flush?

So here's what got me into this mess in the first place..... transmission cooler was leaking fluid into the cooling system. At that time the coolant was pretty nasty! Rad was gummed up pretty good, so i figured it would be easier to replace it. Flush upon flush, (back flush included) conditioners, cleansers used to get the system looking good again. Thermostat seems to work well. After all those flushes I figured I had the system clean. The waterpump is oe.150000Km on the car, guess a waterpump wouldn't hurt eh. It just seems weird that it won't overheat when the a/c is on. One would think that would cause the engine temp to go up. Thanks for the suggestions guys :)

100,275

You might check the engine cooling fan and make sure it is turning on when it is suppose too. If it is not working that would explane the overheat without the A/C turned on, when you turn on the A/C or defrost it turns on the condenser fan out front. Make any sense?

Makes complete sense now, thanks for your input. I never did check that. I know the fan's come on when the heat or a/c is on. So if it turns out that they don't come on, would it be reasonable to guess that the temp sensor is faulty?? Not sending the signal to turn the fan's on?

100,275

That is a reasonable assumption. Don't forget to check the relays also.

How long have u owns it ?

I bought it with 25000 km. Problem is still there. I've checked the fans, they come on when they should. With the crazy weather here in Calgary, it's not to much a problem driving around with heat or a/c, but I really should get this issue resolved.

Your Answer

Grand Prix

Looking for a Used Grand Prix in your area?

CarGurus has 2,684 nationwide Grand Prix listings starting at $1,500.

ZIP:

Pontiac Grand Prix Experts

  • #1
    Js08016
    Reputation
    4,390
  • #2
    Tom Demyan
    Reputation
    2,990
  • #3
    munron
    Reputation
    2,390
View All

Related Models For Sale

Used Chevrolet Impala
479 Great Deals out of 33,615 listings starting at $777
Used Dodge Charger
417 Great Deals out of 27,419 listings starting at $2,495
Used Pontiac Bonneville
518 listings starting at $1,799
Used Pontiac G6
62 Great Deals out of 3,882 listings starting at $1,295
Used Chevrolet Monte Carlo
16 Great Deals out of 1,304 listings starting at $1,950
Used Pontiac Grand Am
1,066 listings starting at $1,899
Used Ford Mustang
709 Great Deals out of 38,398 listings starting at $895
Used Pontiac GTO
10 Great Deals out of 475 listings starting at $5,995
Used Chevrolet Malibu
1,072 Great Deals out of 72,017 listings starting at $1,896
Used Chrysler 300
329 Great Deals out of 17,504 listings starting at $1,000
Used Honda Accord
1,033 Great Deals out of 60,523 listings starting at $999

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.