Fan Always On

[Dacon]

On my '94 GT, my high speed ran fan comes on 15 seconds into the first drive of the day, and won't stop unless the car is off. It will still get to operating temps (thermostat is okay), but the high speed fan is always on. I can let it sit for 2 hours, KOEO and the high speed will start up again, even with the temps very low. If it sits over night, KOEO does not start fan, but if I start the engine, fan starts, turn off engine and KOEO will make high speed fan run after that until it sits for ~8 hours.

ECT sensor is good, pulled one from a friends car, no change. Thinking CCRM. All the voltages/guides are how to check if NO fan is present though, and I am an electrical retard. With a good sensor, how would one determine a bad CCRM with an always on fan?

*edit* Did some more reading on here... gotta check ground continuity in pin 17, fairly sure.

 

[jozsefsz]

Make sure you swapped the right temp sensor, one is for the gauge, the other for engine temperature to the computer. And yes a sticking relay in the ccrm might be the problem. Sounds like you're on the right track, get the pinout for the ccrm and start probing.

 

[Dacon]

No continuity for high speed in pin 17, calling it deceased. Tapping on it did nothing (didn't have high hopes on that...). Ordered one for $80USD... a hard pill to swallow but it is a 20 year old car these days.

Funny how a $80 part makes me think a $400 monthly payment on a newer one would be better lol.

 

[jozsefsz]

If it makes you feel better, newer ones (complete with payments) are only worse when it comes to electronics! Nothing like a GM "Stabilitrak Disabled" message to make you sweat, and it's one of several computers and miles of unshielded CAN wires that's the problem. Here's hoping your CCRM does the trick!

 

[toyman]

You are aware that if the A/C is on the fan will always be on in the high mode?

 

[Dacon]

You are aware that if the A/C is on the fan will always be on in the high mode?

Yes sir, it's how I originally ID'd it as high instead of low speed (initially from inside the cabin, before checking under the hood). Defroster/mix does as well right? Or is that low?

 

[toyman]

Yes sir, it's how I originally ID'd it as high instead of low speed (initially from inside the cabin, before checking under the hood). Defroster/mix does as well right? Or is that low?

The defroster/mix is a different fan and has no interaction related to the engine cooling fan operational parameters.