99 Sunfire GT Overheatin - I think i know

[impulser91]

Okay so my 99 Sunfire GT 2.4L is overheating.

I cannot hear the rad fan turn on. Also, the A/C is not getting cold and i can hear it kick on and off and on and off.. like its trying to work but its just not happening. So before i rip this thing apart what are the ideas out there, heres what i got.

Thermostat
Fan relay
cooling fan switch (my parts store said they had this.. not sure what or where it is though)
Fan motor

Any help is much appreciated. thanks guys.

[davebigs]

I usually start out by eleminating the easier fixes. Thermostat is a good place to start. The worst might that you have a blown head gasket. Is the coolant level being maintained ? Does the tem go down if you turn the blower fan full blast on hot ?

[impulser91]

Originally Posted by davebigs

I usually start out by eleminating the easier fixes. Thermostat is a good place to start. The worst might that you have a blown head gasket. Is the coolant level being maintained ? Does the tem go down if you turn the blower fan full blast on hot ?

Thanks for the quick reply. Temp goes up "slower" when blasting full heat. Coolant level is fine. None missing anyway.

As long as im crusing its all good. temp stays normal. But once im sitting ideling it starts to sky rocket.

[impulser91]

Okay, so i just went down to it and checked the overflow tank. It is at the level it should be.

When i turn the a/c on, the compressor kicks in and the fan is supposed to turn on as well, but it is not. So, from what i gather, the temp switch and the a/c switch are seperate controls for the rad fan so its now eliminated to fan motor or relay. If i am correct.....

Ideas?

[impulser91]

Okay, so i temporarly took my heater blower fan relay and put it into the cooling fan relay and the fan will still not turn on with the a/c on.

So is its safe to assume that its just the Rad fan motor, can i pick up just the motor and replace it, or am i missing something else here?

thanks for any help

[impulser91]

Okay, so after testing the old motor i determined it was the motor that was shot. I replaced it today and when i turn my a/c on the fan is coming on. Leaving the a/c is the only thing that is keeping my engine cool. The fan is still not turning on when it reaches a high enough temperature and is still wanting to over heat. What components do i need to look at to diagnose the trouble maker here.

Im thinking some kind of temperature sending unit but i really dont know enough about these engines to say for sure.

thanks for any help.

[cymdeathlord]

If i remember correctly that have an electric fan so it could be a few things i would hook yo power cables to your fan see if it works that would be the easiest way to check to see if you fan is bad. it could be the fan or a bad heat sensor and it is not kicking in at the right temp because of it.

[impulser91]

Originally Posted by cymdeathlord

If i remember correctly that have an electric fan so it could be a few things i would hook yo power cables to your fan see if it works that would be the easiest way to check to see if you fan is bad. it could be the fan or a bad heat sensor and it is not kicking in at the right temp because of it.

Well thanks for the reply but as you can see from my previous post....

Originally Posted by impulser91

Okay, so after testing the old motor i determined it was the motor that was shot. I replaced it today and when i turn my a/c on the fan is coming on

So its working now when i turn my A/C on... But without the A/C being on the car is still wanting to overheat....

[impulser91]

Just FYI

It turned out that the car has 2 Coolant temp sensors. I had to replace the one for the ECM. It is on the drive side, near a large pipe junction.