rapid heating/cooling

2001 v6es galant with 43k miles on it;I was driving in heavy traffic and the AC on when all of a sudden the AC air started to get warmer, I looked down and saw that my temperature gauge was almost redlining. I shut off the AC rolled down the windows and was about to turn on the heather when the traffic sped up to 30 MPH and the temperature guage dropped quickly to operating temp( i never turned on the heater). There are two stop signs near my house 3 blocks apart within 2 minutes from the first stop to my house as I was pulling into my driveway the temp shot up again. I turned off the AC and let the car idle as that happened it dropped to normal op temp again.

I have checked the coolant level, no coolant in my oil, and no steam out the tail pipe. I have never seen a car heat up and cool down so quickly and so inconsistently. a few hours later after the engine cooled I started it up with AC and it ran for 20 minutes no issues. I then started to drive and BAM it heated up again... ANy ideas? I thought T-stat at first but now I dont know.

Reply to
sportmarty
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You have two electric radiator fans. Are they working? One should come on automatically when the engine is idling hot. The other should kick in (eventually) when the A/C is switched on. Both are controlled by temp sensors that trigger relays.

Stewart DIBBS

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Reply to
Stewart DIBBS

On that year the AC is controlled by the ECU and not separate sensors like the older Mitsus. To test the fans, turn the key to ACC (one click shy of starting) and turn the AC switch on. As long as the car is warm, the fans should kick on.

It may be the thermostat. I would just replace it. It only takes about 20 minutes and is worth the peice of mind. Just don't over tighten the two bolts or you will bust the aluminum housing. If that and working fans doesn't rectify the situation, start looking at the water pump (unlikely) or the harmonic balancer (crank pulley).

Reply to
Nobody U. Know

Thanks for the info... yes I forgot to say all the fans seem to operate. I am going to replace the thermostat. Can I use any antifreeze coolant or is Mitsubishi a proprietary blend? Thanks for each of your help

Reply to
sportmarty

Any antifreeze will be fine. Make sure you actually get the right ratio for your enviroment. Too much antifreeze will cause an overheat (it's antifreeze, not coolant..water is coolant.)

Reply to
Nobody U. Know

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