Dustin Gebhardt
Full Access Members
Does anyone know of a way to look at the PCM inputs/outputs as they relate to the mechanical fan clutch on the '07 Expy's? I have ForScan, if that matters.
I have poor AC performance when at idle. The AC works great at highway speeds, and my gauges tell me that my charge is fine. I suspected that my fan clutch was malfunctioning, but a recent cross-country trip through OK, TX, NM, AZ, and CA caused the fan to spin up whenever the ambient temperatures soared. For example, I was towing a mid-sized trailer and I'd pull off the highway to refuel. I'd leave the Expy running since it was full of passengers and they wanted the AC. When I had refueled and was leaving the gas station, I could hear the radiator fan spin up to a roar and stay that way for probably 15-30 seconds, then the sound would ramp down. To me, this indicates that the clutch is working. Additionally, when the engine is cool, I can only spin the fan about 1/4 to 1/2 of a turn, which seems to indicate that the clutch is working.
Everywhere that I look, I hear that the fan should spin up when I first start the Expy and quickly ramp down, and that the AC engaging should cause the fan to spin up every so often. I get neither of these. This, plus the trip through the desert, points to a PCM signal issue. My next step is to ground out the clutch wiring connector to verify that the clutch is working. But how can I "look into" the PCM to see what it sees and what it's sending to the fan clutch? Or should I look in another direction?
I have poor AC performance when at idle. The AC works great at highway speeds, and my gauges tell me that my charge is fine. I suspected that my fan clutch was malfunctioning, but a recent cross-country trip through OK, TX, NM, AZ, and CA caused the fan to spin up whenever the ambient temperatures soared. For example, I was towing a mid-sized trailer and I'd pull off the highway to refuel. I'd leave the Expy running since it was full of passengers and they wanted the AC. When I had refueled and was leaving the gas station, I could hear the radiator fan spin up to a roar and stay that way for probably 15-30 seconds, then the sound would ramp down. To me, this indicates that the clutch is working. Additionally, when the engine is cool, I can only spin the fan about 1/4 to 1/2 of a turn, which seems to indicate that the clutch is working.
Everywhere that I look, I hear that the fan should spin up when I first start the Expy and quickly ramp down, and that the AC engaging should cause the fan to spin up every so often. I get neither of these. This, plus the trip through the desert, points to a PCM signal issue. My next step is to ground out the clutch wiring connector to verify that the clutch is working. But how can I "look into" the PCM to see what it sees and what it's sending to the fan clutch? Or should I look in another direction?
