help with radiator fans

[megadola]

I have a 99 malibu 3.1 v6 and the car has been overheating do to the fans not coming on. They do come on with the air conditioner but not when the engine reaches temperature. It ends up overheating and the fans never come on.

I checked all three relays by supplying power and ground to the relay and checking for continuity with a volt meter and they were working. I changed the engine coolant temp sensor and still nothing.
Is there any known problems with this. Like wire or wires that commonly break. Any general idea on where I should be looking. I am lost here any help on this matter would greatly be appreciated.

I just edited this post because I have an update. I took the harnness off the coolant temp sensor with the engine running. The fans kicked on.
From reading other post I now beleive it could be the computer. I dont want to change it if it isn't that because it is an expensive repair if it does not fix it.
Does anybody believe it could be the pcm.
Does anybody know what is involved in changing the computer the haynes book says it has to be calibrated or something at the dealership is this true. what happens if you dont reprogram it will the car run at all.

Any help would greatly be appreciated

Thank you
Nick

[hparikh]

I have same problem in my car (year 2000 model). Did you find any answers?

Originally Posted by megadola

I have a 99 malibu 3.1 v6 and the car has been overheating do to the fans not coming on. They do come on with the air conditioner but not when the engine reaches temperature. It ends up overheating and the fans never come on.

I checked all three relays by supplying power and ground to the relay and checking for continuity with a volt meter and they were working. I changed the engine coolant temp sensor and still nothing.
Is there any known problems with this. Like wire or wires that commonly break. Any general idea on where I should be looking. I am lost here any help on this matter would greatly be appreciated.

I just edited this post because I have an update. I took the harnness off the coolant temp sensor with the engine running. The fans kicked on.
From reading other post I now beleive it could be the computer. I dont want to change it if it isn't that because it is an expensive repair if it does not fix it.
Does anybody believe it could be the pcm.
Does anybody know what is involved in changing the computer the haynes book says it has to be calibrated or something at the dealership is this true. what happens if you dont reprogram it will the car run at all.

Any help would greatly be appreciated

Thank you
Nick

[RacerX29]

I am having the exact same issues. My 2000 Malibu LS overheated and spilled out coolant from the overflow. I replaced the ECS (engine coolant sensor) and that did not help. My fans will not run unless I turn the A/C on. Then they both run continuously even if I turn the A/C off and leave the car running.

If it is the actual "computer", I'm gonna try getting one from the same model year, with the same features, Malibu at a junk yard. If anyone would have any insight, I would greatly appreciate. Thanks.

Jim

[bermis519]

You need to replace the engine temp sensor, it's an eight dollar sensor, it temperature controled and kicks one at a preset temp. The sensor it located near the thermostat and it's within about two inches of the thermostat. It's a pain in the ass to get to, basically have to pull a few things out of the way...really no big deal. But worth it.

Let me know if this helps,
mike