jun_1.8T said:
ok....i got confused there with the pins for the thermoswitch. i have confirmed today that i have 12 volts coming out of my pin#2 for the thermo switch harness. did the test but still no fans came on for both slow and fast speed. took the car for a drive and only the drivers side fan works when i turn on my a/c. the car would still overheat when i let it idle and no fans work during this point. so...my fan should be ok as it runs sometimes right??? could it be my FCM that is bad??? i would still try to power up my fans straight from the battery to completely rule out my fans.
one question....should both fans come on at the same time eventhough im not using my a/c??? and if ever my FCM is bad...should it cause my fans to not run on slow speed???
thanks!
Go ahead and test the fans directly putting power to them.
It sounds to me as if the most likely scenario is two bad fans.
They should never run singly, NEVER RUN SINGLY, both should always run together.
The most likely scenario is that one fan is getting enough power through the stuck brushes to run when the vibration from the running engine, and it has the 14.4 volts instead of 12.5 volts, but not in the low voltage, no vibration scenario.
The fact that one low speed fan does come on with your AC indicates it is likely that your Fan Control Module is working. In this condition they are both started by the same relay inside the FCM.
The slow speed fans can be started from the thermoswitch, even with the key off, totally independent from the fan control module.
The fan control module is used for all the start conditions except the radiator fan thermoswitch in low speed.
Fast speed requests from the thermoswitch, the ECU high temperature, or the Air Conditiioner high pressure all require a functional Fan Control Module. ALL FAST SPEED OPERATION REQUIRES A FUNCTIONAL FAN CONTROL MODULE.
If you were at my place we would directly test the fans, expecting one to certainly not run, the other to probably not run. Even if they both ran, based on what you have told me, I would probably clean the brush holders on both of them.
Dan