Fan doesnt shut off??????

[trickstang94]

I may be stupid, cause maybe I never noticed it before or whatever!!! Today I drove to work(8 min drive max), when I shut my car off the fan didnt turn off. Not thinking anything about, but wondering if it was supposed to do that, I went on with my day. After wondering if it was going to stop, I went outside (2 hours later) to check. The fan wasnt on anymore. I went to start it and it barely turned over but started. I let it run for a couple minutes then shut it off. The fan didnt come on (obviously not hot enough). At the end of the day I went to leave and my car struggled again to start even worse than the other time. When I got home (again a 5-8 min drive the fan stayed on). I didnt want it to drain the battery so I disconnect the fan. Does anyone have any ideas or am I stupid. (Probably stupid but at least i'll know)

 

[bill302]

the pcm (power control module)recieves a signal from the ect (engine coolant temperature sensor)which it uses to decide when to turn the cooling fan on, to turn the cooling fan on, the pcm sends a signal to the ccrm(constant control relay module), which houses the cooling fan relay and relay control unit. the cooling fan relay and relay control unit operate the cooling fan unit until the pcm decides the fan should be turned off.

test pcm and work your way back run a search jrichker posted how to test info. a few days ago

 

[trickstang94]

Thanks, I'll try to find it.

 

[philoldsmobile]

so what was the outcome?

my fan stayed running on my 96 (late 95 build) 3.8 mustang for quite a while the other night, but operated normaly since..

someone sugested that it may be the air con?

iis it worth replacing the coolant temp sensor out of course anyway?

 

[trav_19]

i had that problem with my 93 when i switched to a electric fan... my thermostating kit was leaving the fan run till it was cool even if the car was not running....i struggled with it for a summer then i by passed the thermostat kit and keyed it if the cars on the fans on and if its off so is the fan made my life simplier lol

 

[philoldsmobile]

thats aftermarket though?

is there any reason that a factory stock car would do this?

 

[GTA_V6_Mustang]

Could be a short to power if the controller is on the power side and if the controller is on the ground side, it could be a short to ground. But for your sake, I hope its neither. My old 3.8 had the fan stay on a cuple of times after the car was shut off but always turned itself off and never drained the battery so I dont know what to tell you. If your battery doesnt drain I wouldnt worry about it.

 

[HISSIN50]

My bet would be a latched relay in the CCRM,a failing ignition switch (ensure no other systems stay powered up with the key-off), a bad EEC relay (staying on), etc.

Get it to keep the fan on with they key off. Be real careful here - you will have your hands near the moving fan for testing!

Test the fan motor to see which speed is staying hot. IIRC, the bottom fan wire is high speed and the middle is low speed. Now that you know which speed is staying on, you can test that particular relay's I/O's.

If it's low speed, check the following CCRM Pins:
Pin 1 and 2 should be hot only with the key on and the car at 208*F.
Pin 3 and 4 should be constantly hot
14 should receive 12 volts at 208*F.

Ensure Pin 14 is dead with the car over 208*F and the key off.

For high speed:
3 and 4 need to be hot at all times again.
Pin 6 and 7 should show 12 volts when Pin 17 shows ground (with Max AC on or at 228*F).
Ensure Pin 17 does not show continuity to ground with the key off.


Good luck.

 

[philoldsmobile]

no other curcuits were powerd up with the ignition on, and its never done it before or since....

possibly a sticky relay, are they easy and cheap to replace?

also it was a very damp day, and i had steam cleaned the engine about a week before, is it possible there was some dampness inside something?