I just discovered that my High Fan is not coming on. I can hear a click from the CCRM when I back probe pin 17 to ground and a steady clicking when I try to switch it on through the EMS. Need some clarification on manually overriding the control relay to verify that the fan will come on high before replacing the CCRM. From my schematics it appears that if I jumper the O/LB at the fan connector it should run on high. What I don't see in the schematics is what regulates the fan speed. Is it just a resistor in the low fan relay or in the fan control motor circuit that reduces the voltage to the motor?
High Speed Fan Control
- Thread starter toyman
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Richard, AFAIK the PCM takes care of the switching.
You've probably seen it before but for a quick CCRM HEDF test:
If high speed doesn’t come on before ~230*F or with the A/C turned on, but CCRM Pin 17 shows continuity to ground: With the key-on, check CCRM pins 6 and 7 for 12 volts when the high speed fan should be on. Check Pins 3 and 4 for constant 12 volts. Check Pin 13 for key-on 12 volts.
Be sure the Fan fuse is ok and that if you have a circuit breaker on the high-speed circuit, that it isn't opening.
You've probably seen it before but for a quick CCRM HEDF test:
If high speed doesn’t come on before ~230*F or with the A/C turned on, but CCRM Pin 17 shows continuity to ground: With the key-on, check CCRM pins 6 and 7 for 12 volts when the high speed fan should be on. Check Pins 3 and 4 for constant 12 volts. Check Pin 13 for key-on 12 volts.
Be sure the Fan fuse is ok and that if you have a circuit breaker on the high-speed circuit, that it isn't opening.
Just to clarify, I have an AEM-EMS so I can adjust the fan temp settings. I'm almost positive the high fan used to came on when the AC was turned on. I'll check the pins as noted. The fan does come on at low speed as commanded by the EMS so that would indicate that power is going to pin 3 from the 60a fuse in the power distribution box. If there is a circuit breaker in the high speed circuit where might it be located. I don't see a reference in the schematics. The schematic shows pins 6 and 7 are the high speed fan control relay outputs to the fan control motor. I'll check these as well.
The circuit breaker is (installed) between the fan motor connector and the pigtail. It was a band-aid retrofit on some cars because high-speed could short out and catch things on fire. IIRC it was Recall # 01S30.
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