my 98 monte carlo cooling fans will not speed up when temperature goes up. When the car starts to get hotter the ac goes off. When I am driving normally, the temperature and ac run perfectly...


Asked by Jul 18, 2013 at 12:58 AM about the Chevrolet Monte Carlo

Question type: Maintenance & Repair

My 98 Monte Carlo has just had a new ac system installed and it works perfectly when the car is moving down the road.  However when the car is parked and at idle it starts to get hot and the ac goes off.  I've noticed the cooling fans only spin at one speed when they should increase as the temperature goes up thus causing the ac to switch off.  Tell me what you think, please....I live in Phoenix and I need the ac to work and the car not to get hot...

17 Answers


The fans as far as know run at one speed and are controled by engine temp increase or if your A/C is switched on. It is possible you fan motor could be going bad and its not working at normal speed.

2 out of 2 people think this is helpful.

When was the last time you serviced your coolant system? undervoltage condition is hurtful...put a NEW battery in there, clean the 1/0 battery cable attachment to ground...the fan will turn at the normal rate then~


Interesting...I appreciate your answers...Before when the car was running normally the cooling fans would run faster when temperature went up....they would really spin up and move serious amounts of air keeping the car temp in the normal operating range....Now they just spin at a low speed no matter what the temperature is, and that is the problem....I admit I have not serviced the coolant system in quite a far as the battery, it was replaced 2 weeks ago when an interior light was left on for days and drained the this Phoenix heat the battery died...Heat and batteries do not mix, especially this oppressive heat.... My question is, are there relays that are bad and how to find them and could it be the coolant temp sensor that is causing all of this? Thanks

1 out of 1 people think this is helpful.

temp sensor....what else?


Thanks...I pray it could be that simple...Would this be a good place to start if I were to try the old 'process of elimination' path like we used to in the old days? In the old days, most cooling problems could be solved with a water pump, thermostat, and clutch fan...approximately 50 to 60 dollars....but now there are too many parts and they are where is the cooling temp sensor?

1 out of 1 people think this is helpful.

probably at the base of your radiator....but there may be more than one....maybe so the computer will know how to enrichen the to know when to switch the cooling fan on and one for the temperature gauge/status...let's hope there is only one and a very smart ECU...will spend some time with you now~

Okay, it's in the block on the front~

2 out of 2 people think this is helpful.

if air conditioning is equipped there is a Thermo-switch for the electric fan~

40 let you know I had the ac system compressor, drier, orifice tube, the whole system and it works great...when the car is running down the road...but when it is at idle with the ac on, the temperature gradually rises and eventually the ac goes off until I put in drive and start down the road, then the ac comes back on and the car cools down to normal operating temperature and all is I know here in Phoenix the heat is higher and all ac systems are taxed to the max but this should not happen...the fans simply do not spin faster when the car temp goes up...when they used to I had no problems...

2 out of 2 people think this is helpful.

apparently the block sensor is the only show in town (barring the a/c blower)~


great the block sensor controls the whole system as far as the fans go?

"engine coolant temperature gauge sensor" is what the cartoon says, but is it the ECU information base? hasta be~ the fan switch is it's own part of the electrical scene~ appreciate you acknowledging the time spend in trying to figure this all out...different, but special, like the differences in Steering Wheel design....duh, they all do exactly the same thing...why must they all be different?

no...they do not spin faster...12 volts is where they like to be~ could be deprived of Amperage tho~

1 out of 1 people think this is helpful.

NO....the a/c fan has it's own on/off may be right that the other fan is controlled by the ECU telling it that it is time to come on...yesss~


I would check for 12 volts at the fan, if all checks ok I would replace the fan. In your extra hot climate I'm sure those fans hardly had an easy day from the get go. Heres link for a replacment fan.

2 out of 2 people think this is helpful.

great info, I appreciate it...I will be doing more research and have set aside this weekend to figure this out....and yes these fans have had a trying life to say the least....I live in the land of the 12 month ac season and 4 months of purely hellish heat...I will get back as soon as this is all figured out.....thanks

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