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AC clutch and coolant fan don't engage

Ecomike on Sun June 03, 2012 1:58 PM User is offlineView users profile

Year: 1996
Make: Ford
Model: Taurus
Engine Size: 3.0
Refrigerant Type: R-134a
Ambient Temp: 70-95
Pressure Low: Normal
Pressure High: same
Country of Origin: United States

I am trouble shooting my son's AC again. Been in the kids bumper car repair lot for last 18 months, now fixed and running again. I tried replacing the CCRM (after connecting some dots*) this week thinking it was the most likely culprit, but it made no difference.

Last time I worked on the AC the 4 pin switch contacts were loose, the switch up top near the power steering pump, which I believe is the HPCO switch, I cleaned and tightened the female connectors and it worked for about 18 months? 2 years later wiggling and tightening the female connections no longer worked, so I checked the charge (think it needed refrigerant), and found the system was still fully charged. I forget exactly what I did in 2010 but I jumped something (likely the 4 pin HPCO switch, but I do not recall for sure), and I got the clutch to engage, IIRC, and the AC worked perfectly, so I knew at that point the clutch, compressor, refrigerant level, etc was all good. He drove it with out the AC and had the accident months later, then it set up waiting for time to rebuild the steering....which I finished last week.

I discovered the *CCRM idea this week when I suspected the e-fan coolant fan was not working right (later turned out it was working right), and the coolant fan does not turn on when I turn the AC on (goggle lead me to the CCRM, which I was not aware of before)!!! So I figured, perhaps 2-3 relays, or worse, in the CCRM was fried inside. Well I replaced the CCRM, and no joy. Note that the coolant fan does come on at 215 F according to my OBD-II scanner (Verified last night)....and does cycle between about 215 F and 204 F, so I guess I was wrong about the CCRM being bad. I was thinking that one fan relay out of the 2 might be bad......because the dash gauge acts like it is overheating before the coolant turns on (I am use to old gauges that read lower.....), but it seems that is normal for the Taurus temp gauge.

So I am wondering if I am missing something, perhaps a switch on the AC dash is not getting the signal to the PCM?, or a hidden fuse I have not found, or is it a bad AC pressure switch? The dash controls all seem to work except for AC clutch and coolant fan not turning on, the HVAC blower works fine.

How do I test the AC pressure switch(s), is there just the one (dual?) 4 pin switch, or a second, hidden pressure switch buried out of sight? Is there another part that could keep the coolant fan from running as well as the clutch from engaging AT THE SAME TIME, since neither come on when I turn the dash controls to AC on?

How do I test the 4 pin switch, and the harness side of the 4 pin switch!

Thanks for the help!!!

Edited: Sun June 03, 2012 at 2:05 PM by Ecomike

Ecomike on Tue June 05, 2012 3:42 PM User is offlineView users profile

Hmm, no questions, no possible answers?

mk378 on Tue June 05, 2012 4:56 PM User is offline

Not knowing that car specifically, I'd obtain a schematic of the car and trace the signal through starting from the control panel. Much safer to probe stuff than to jump it.

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