Engine Size: 2.8
Refrigerant Type: R134a
Ambient Temp: 85+
Country of Origin: United States
When I turn on the A/C button that is on the electronic climate control unit, the auxiliary fan in front of the condensor turns on. However, the compressor won't engage until about 10 minutes of driving, at which point I'm sweating. The hotter the day is, the longer it takes for the compressor to engage. If the car is at an idle and the compressor engages, the engine stumbles for a split second and then is fine as the RPMs come back up.
When the compressor runs, the air coming out of the vents is ice cold with over a 45 degree temperature differential with ambient (if that means anything). I haven't had a chance to hook up the manifold gauges yet to check pressures, but they were fine last fall when I checked.
So does this sound like an issue with the electronic climate control unit or something mechanical? What are symptoms of a failing a/c compressor clutch?
Edited: Fri June 10, 2011 at 2:49 PM by nyc951
That is a symptom of a worn clutch (inconsistent engagement especially when hot), but you can usually make the gap smaller and get it to work again.
It seems more and more like it's a faulty clutch. What holds the clutch onto the compressor? Snap rings?
Most non-GM compressors have a nut or a bolt in the center to the compressor shaft. Remove the nut or bolt and the plate should slide off. You will need to devise some way to keep the plate from turning to loosen it, there is a special tool for that but a screwdriver can work. Once the plate is off there are shim washers on the shaft behind it setting the gap. Remove some washers and reassemble. This can be done with the system remaining charged if you can get access to the clutch with the compressor still installed, or unbolt it from the engine but don't disconnect the lines.
Edited: Sun June 12, 2011 at 1:51 PM by mk378
If you are real technical, you can use a broomstick to test the clutch theory. Whack the center of the clutch assembly with a broomstick right after you have turned the system on. If that 'nudge' gets it to clack into place and start rotating, you have a pretty good indication that the gap is a little too wide for the magnetic field to draw the clutch into action.
You can actually measure the gap using a feeler gauge, if you are more technical than the broomstick crowd.
Me, I would have suspected the control head, given that it is a BMW. They do tend to over-engineer some things, IMO. You may have a fan speed control that is on the way out, and the blower motor is not coming up to speed until you have been on the road long enough for the chopping transistor to start conducting, and the control head, speaking with a Cherman accent, sez: "Hmmm I zee vee haf no blower speed rotation reported by zee monitor. Vee vill not engage the clutch until we get some blower action" .. That DOES happen on Odysseys, and you will get nothing until you put it on Hi-manual, and even then, the A/C won't engage because it doesn't get the speed control feedback. Oh, my, things are so much fun these days.
simplificate and add lightness
I received another (used) control head today and the compressor did the same exact thing - didn't turn on until after a while.
I'll try the broomstick trick - that was a funny post! Is there such a thing as the "gap" getting too narrow? Do I need to be careful about making the gap so narrow that it'll hurt the compressor? I guess if the clutch is on the way out, who cares, huh? How much time will decreasing the gap buy me?
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