Engine Size: 2.5L
Refrigerant Type: R12
Ambient Temp: 85F
Country of Origin: United States
OK I diagnosed my problem as a bad coil in the clutch electromagnet (totally shorted out). Installed used coil and resurfaced used pulley and plate friction surfaces. Now the clutch engages the compressor but there is a new noise. It's NOT the clicking when the clutch engages and disengages. It's a different clicking or ticking heard only after the clutch engages. It sounds like a series of electic arcs (or a marble dropping on metal) and is not a constant sound related to RPM. More of a random ticking that gets more frequent as the system heats up. When the AC is tuned on, it is very silent for about 2 or 3 minutes (except when clutch cycles). Then a few clicks start, then more, then I get scared and turn it off. It's blowing ice cold. One time, I heard the clicking, stopped the engine, popped the belt off very quickly and rotated compressor by hand. It felt smooth. And the pulley rotates freely as well on the bearing.
One more hint. When I first put the new clutch on, it was too tight. Even when AC was off the clutch was trying to spin the compressor. It was rubbing the friction surface but not well enough to fully engage. The clicking I'm refering to was quick to appear when I turned AC on. I removed the plate and added a spacer washer and when I put it back together, it seemed to work perfectly. I took for a test drive and prematurely declared victory. Then when wife drove and I was outside, I heard it again. It's much quieter than a clutch engaging sound. When driving, I have to turn fan to low and open windows to hear.
My best guess is the new coil is arcing.
My next diagnostic is to run the AC till it clicks, then drop the belt and turn it back on. If it still clicks, it's got to be the coil..... I think.
Anybody heard this sound before? Other advice?
I see it is not a new clutch, but a resurfaced one. Did you check the clutch gap? I set clutches between 18-20 thousands. Also fallow the clutch wires making sure they did not get damaged with the first failure. Hope this helps and good luck!
Try testing with the belt off and the clutch hotwired to the battery (engine off of course). See if there is any dragging when you turn it by hand. After several minutes, the clutch coil will warm up and may expand to the point it starts to drag.
Well I ran several tests and am still not sure what the problem is. I ran the system till the clicking started and then darkened the garage but saw no visible arcing. After a while the clicking is almost continuous like a high rate machine gun. Then I turned it off and quickly dropped the belt in about 20 seconds. Rotated the pulley and outer plate and both turned freely with no noise. So I don't think it's the compressor or bearing. Then I ran engine with AC on, with no belt (easy way to put power to coil) and no clicking ever showed up. I even rotated compressor by hand while it was running but again it turned smoothly and clutch was engaged. I think this all means I have a bad coil that is arcing after it gets hot. And it only gets hot enough when the compressor is operating.
I can't see how a bad clutch gap could cause this since it makes the noise only when clutch is engaged, and it doesn't appear to slip. But please correct me if this is wrong.
These coils are almost impossible to come by. I had to buy a whole rebuilt compressor to get the used coil I'm now suspicious of. Can an auto electric repair place rewind one?
Try connecting an analog ammeter in series with the positive lead that feeds the clutch. If the meter pegs in the wrong direction, reverse the leads. If the coil is opening or shorting intermittently, the ammeter needle will pulsate. If the coil is good, you will get a steady reading. If there is an open or short in the circuit that feeds the clutch, the results will be the same. The way to isolate that, is to feed directly from the battery. If you do feed from the battery, hook up gauges to monitor pressures, as the pressure cutout will not be in the circuit. As I recall, clutch coils usually draw around 1 or 2 amps.
I think the coil is OK. Low voltage coils don't arc noisily, they just burn up.
Much more likely it is mechanical interference of some kind. Does the clicking vary when you rev the engine? It could be from inside the compressor (the compressor part).
It varies when the rpm is NOT changed but I'll check with revving the motor. Maybe I'm spinning it too slow by hand to get the clicks. I'm also considering rotating by electric drill. That way the coil will be off but spinning the compressor. Not sure how I'll pull that off. I'm considering the ammeter test but those connectors are murder to get to.
This has turned into a 3 month project. :-(
Thanks for the advice folks,
We've updated our forums!
Click here to visit the new forum
Copyright © 2016 Arizona Mobile Air Inc.