![]() 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak. Anybody out there ever have one like this- or is this just my lucky day!!!! - The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!! Just a thought. Foot on brake may be a factor as well.but not sure yet. Can anyone find a wiring diagram that relates a/c request signal to the park/neutral switch or to TCC circuit? - perhaps I'm getting a short to ground when in Park in a P/N switch. I called the owner- he said his wife's biggest bitch was that when she'd start the car to cool it down while she was loading it- that it did not cool-since it was in Park- so we've confirmed that- I told him, I was going to test drive it- because I could not get a/c to come on- but it cooled fine when I pulled it in to my shop.there is something terribly amiss here. One of my issues is that I can't seem to get the face plate (facia) removed that covers the radio and control head- there are two 7mm screws beside cup holder- the rest snaps out- but there is evidently a screw or two behind the cupholder- and the cupholder refuses to come loose to remove it-the stop tab is extremely rigid- looks like it should bow down to remove- but it doesn't do it- gee, I hate to break it loose.anyway, I tested at PCM input which should be just as good as control head output and I get the 5v signal there- just not when vehicle is in park- which took me two hours to figure out- since no one usually test a/c circuits in anything other than Park. The 1996 U-van service manual I have clearly states that the a/c request signal goes to PCM and a parallel path the TCC circuit- I will look up wiring diagram for it to compare to a 2001 U-van. Whwn a/c is on, (not in park and foot on brake), I can turn on/off the 5 volt signal just fine with the a/c button. I get 5 volts from grn/wht at PCM from control head whenever vehicle is not in Park-and mostly on when in any other gear.nothing else in control head is amiss- beating on it does nothing. Okay- plot thickens- I thought since I was having no luck parked- and that owner says a/c is intermittent- and my test it has been several hours running with no a/c request at all- that I should take it out and drive it-with volt meter attached to drk grn/wht at PCM-and tech II showing no a/c request- I drop it in reverse and a/c request is suddenly yes and volt meter show +5v-Then back in park and request is no and volt meter is zero.drop it in drive- request comes on, then drops out-RPM related? I can reve it any amount in park and a/c request and volt meter are negative.drop it in any gear, or neutral and request is now intermittent- but mostly on- just as owner states.WTF I say.older vans 1996 or so had a lead from control head that fed TCClock-up- so that torque converter would lock up with a/c on- to keep from feeling engine drag and cycling clutch I assume-but do these newer ones 2001+- the schematic for HVAC shows none. Seems I get no a/c request at all- and when I check a/c rquest signal (grn/wht wire) from control head- I get no voltage- Tech II will energize a/c relay and compressor- when reuested on Tech II relay checker.but this thing was cooling fine when I drove it into my shop. So here it comes- complaint is doesn't cool all the time- charge level pulled and weigheded out fine. If so the switch might be bad.Year: 2001 Make: Chevrolet Model: venture single system Engine Size: 3.4 Refrigerant Type: 134a Hold it for about 8 seconds to see if the test light goes out before the time is up. ![]() Each time you push the switch power should go to the window motors for as long as you hold the switch. Next, use a test light to check for power at the motors when you push the switch (even with windows closed). Also, check to see if you can push the windows close after the motors have stopped running. ![]() Check for anything which they might be getting stuck on, preventing them from closing. If there is power there, the switch is bad and the module has to be replaced.įor rear windows, check for arms which close windows binding during the closing process. With the ignition switch on, and the HVAC control module switch in the "OFF" position there shouldn't be any power on the ORG wire at terminal "C" (this is the blowers HI setting). Terminal "A" (DK GRN) is gorund (through the control module). Power comes in to the switch on the Brown wire at termina "B" (12volts). You'll have to remove the control module by removeing the trim around the radio assembly, and them remove the screws/bolts securing it to the dash. Check the HVAC control module (also known as the blower motor switch assembly), located just blow the radio.
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