1999 Alero Fans Won't Turn On

Alerodriver17 · 10-29-2016, 05:44 PM

Ok the title explains it all. I have a 1999 Alero, the cooling fans don't work. I pulled the relays and started it, NOTHING! Turn on the AC, nothing. I replaced the cooling fans. Still nothing. This is messed up. I connected a test light to the negative of the battery and proved the power wires and it was definitely getting positive power as the light lit up. What should I do? I wanna get this fixed asap!

Thanks for the help.

falloutboy · 10-30-2016, 10:54 AM

Tried to jumper the relays? As just pulling them out, won't do anything.
Than again, u got + to the fans, do you have good ground?

A wiring diagram helps to trace the routes and lines and what to test. BUT keep in mind, they are turned on by the ?? BCM ?? so, certain conditions have to be met, so they turn on.

03Alerosil · 10-31-2016, 10:16 AM

PCM is the controller for the fans. It is also the grounding circuit for them and most other circuit in the car. I'd check the temp sensor by the thermostat. That tells the PCM the engine temperature which in turn, turns the fans either on low or high speed. Being they don't work even with defrost or A/C, I'd tend to think that it's a ground issue. If everything checks out then it's the PCM because the ground circuit runs through it.

Alerodriver17 · 10-31-2016, 11:19 PM

Ok. I was told that the fans not coming on with the AC could be because of low freon pressure. I'm going to try the temperature sensor and see if that works.

03Alerosil · 11-01-2016, 07:01 AM

Quote:

Originally Posted by Alerodriver17

Ok. I was told that the fans not coming on with the AC could be because of low freon pressure. I'm going to try the temperature sensor and see if that works.

That is correct as well because the compressor clutch wouldn't be running. Defrost should still turn them on.

Alerodriver17 · 11-06-2016, 03:10 PM

I replaced the coolant temp sensor and the temps rise quicker but the reading doesnt seem so sporatic. But after driving for a bit, the car got to 222 degrees. This is ridiculous. It doesnt over heat on the highway or anything just in constant stop and go traffic. Help me please?

03Alerosil · 11-07-2016, 10:48 AM

222 degrees is pretty normal for an Alero. The fan set-up just sucks. I have to run with either my A/C on or my defrost all the time just so the fans will work. Taking it's toll of the compressor clutch though. If I were you I'd look at manually wiring the fans so you can flip a switch to turn them on if the temps concern you. Mine hits 215 - 220 with the fans running accord the the scan tool. That is normal though as a 195*F thermostat isn't fully open until roughly 215*F.

zzyzzx · 11-14-2016, 01:59 PM

You need to learn how to troubleshoot electronics and use a schematic and multimeter (sometimes referred to as a "voltmeter"). Just replacing parts like that only ends up wasting money and adding to your frustration. Cooling fans are easy enough to bench test.

03Alerosil · 11-15-2016, 09:20 AM

Quote:

Originally Posted by zzyzzx

You need to learn how to troubleshoot electronics and use a schematic and multimeter (sometimes referred to as a "voltmeter"). Just replacing parts like that only ends up wasting money and adding to your frustration. Cooling fans are easy enough to bench test.

I completely agree. Very easy to test. just battery positive and negative. Even testing ohms to check for resistance would be easy with the fans.

Alerodriver17 · 11-17-2016, 02:24 AM

So you are telling me that 222 degrees is normal for this car? So if I get it heated up to above 222 the fans should turn on? Is it possible that maybe a gasket has blown and something is wrong. Someone told me that it may be the recovery tank. If the threads are stripped and losing pressure the cooling system may not work correctly. Does that sound correct?

a.graham52 · 11-17-2016, 08:44 PM

First of all, don't hack up the wiring. You will make more issues.

Secondly, if there is no charge in your a/c then the fans will not run. Turn on a/c and verify the xompressor cycles.

Third, don't follow the temp guage, it's just a guage. Not very accurate other then repOrting consistincy.

Four. 220 is acceptable temp. Fans turn on a bit higher like 230-240ish. Under normal driving your fans will never turn on.

5. Relays, high and low make it go. Look at the relay. 4 numbers. Find the high number and low number. Find their terminls. Then jump slots in fuse block for said terminals. If your fan side of the relay is good then they should work.

Next take a test light hooked to ground... test the other 2 terminals in the blocm. One should have power, other should not.

The one with no power, if you take your test light hooked to btater should light ONLY IF the fans are commanded on. Unless you can do that with a acann tool, we have covered all you can do.

Lastly, check for open fuses.