joshmullins8

Both of my fans come on as soon as I start my car up, what coiuld cause that, I have no SES light on and Advanced Auto says that they cant scan it unless the SES light is on. Is it bad for the fans to come right on?

joshmullins8

Also my low coolant light comes on right away also but the fluid are ok, could that have anything to do with it?

94SLUG

I had this problem like 10 years ago, it was the sensor in the water pump.....

Injuneer

You can scan the PCM at any time. The SES light does not have to be on, the engine doesn't have to be running, etc. Key has to be in the "run" position. Does your Advanced Auto even have an OBD-I scan tool?

There are codes that don't turn on the SES light.

Its not "bad" for the fans to turn on at startup, but it indicates a problem with the engine/sensors. Its not good for the fans to run all the time. Unnecessary wear, and may cause the engine to run too cool.

Low coolant light does not connect to the PCM, and will not turn on the fans. Not related.

killpro

why would it be bad for the engine to run too cool? I had a bad ground before on my fans, and ended up wiring it up...so the fans are on all the time, never see's over 180.

Injuneer

Your engine oil has to reach the temperature required to prevent condensation of the water vapor in the blowby gasses in the crankcase, and to boil off any vapor that does condense when the engine is not fully warmed up. The water stays in the oil, forms acids and starts to eat things (like the bearings) up.

Additionally, the lower the temperature of the coolant, the lower the thermal efficiency of the engine less power. You're pulling heat out of the combustion chamber that's supposed to be used to build cylinder pressure during combustion. And you get less complete combustion at lower temperatures, increasing the presence of CO and unburned HC's in the exhaust - which if purlely an emissions issue.

dalynchmob

I was banging my head against the wall when my fans were running all the time with no code. Ended up paying to have it fixed. It was a bad high pressure switch in the a/c line.

95mysticta

Im having some similar issues with my fans kicking on faster then usual and then the idle and engine runs like crap like it is a miss or something. But when cool it runs mint and revs perfect till it gets warmed up. Ive always been told that it was the sensor on the the water pump. Was also told that if you disconnect the plug from the sensor it will change and that would make it out to be that sensor but i did and nothing changed.

dalynchmob

Yours sounds like a ICM or OPTI maybe.

Injuneer

Have you scanned it for codes?

ayers1967

Remember , when its warms up the ecm goes into closed loop so you may have a problem thats only in closed loop mode. Check it for codes.