Automotive Air Conditioning Information Forum (Archives)

m32825 on Sat April 07, 2012 4:19 PM

Year: 1987
Make: Toyota
Model: Camry
Engine Size: 2.0L
Refrigerant Type: R134a
Ambient Temp: 90F
Pressure Low: 30
Pressure High: 200
Country of Origin: United States

The A/C on my old Camry is giving me problems. When it operates the pressures look good, I watched it run fine and blow ice cubes for 15 minutes straight today, compressor running the whole time, then I cycled it off and back on and it cut out with the blinking light on the A/C switch after about five seconds. Before it cut out I noticed that the clutch was turning much slower than the pulley, so the good news is that the rotation sensor is working fine, but there's some other problem. The shop manual says the clutch should measure 3.6 - 4.0 ohms, I'm measuring 4.5 ohms when everything is hot. Also, seems more likely to work on initial start up than after running a while, but I need to gather more data before I can say for certain. I pulled the compressor and checked the clutch air gap, it is on the money. I'm guessing the magnetic clutch is weak, with performance degrading as it heats up, what do you guys think?

-- Carl

mk378 on Sat April 07, 2012 6:48 PM

Make the gap as small as possible without it dragging when off. The resistance of the coil normally increases when hot, making the magnetic force weaker and requiring a smaller gap.

bohica2xo on Sun April 08, 2012 4:01 AM

Sounds like the clutch is pulling in, but is slipping.

Is there something lubricating the clutch? Slung oil from a power steering pump, or crankshaft seal?

I would de-grease the clutch mating surfaces with some brake parts cleaner, then cycle the clutch a few times.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

m32825 on Tue April 10, 2012 8:44 PM

Quote
Originally posted by: mk378
Make the gap as small as possible without it dragging when off. The resistance of the coil normally increases when hot, making the magnetic force weaker and requiring a smaller gap.

Thanks for the suggestion. Last round I adjusted the clearance to the minimum, it does a little better, but behavior is still the same.

-- Carl

m32825 on Tue April 10, 2012 8:50 PM

Quote
Originally posted by: bohica2xo
Sounds like the clutch is pulling in, but is slipping.



Is there something lubricating the clutch? Slung oil from a power steering pump, or crankshaft seal?



I would de-grease the clutch mating surfaces with some brake parts cleaner, then cycle the clutch a few times.



B.

Interesting suggestion, because I did have a power steering leak that I fixed a few months ago. On the other hand, the system worked fine until recently. When I had the clutch apart to adjust clearance I cleaned everything I could get to. I'm leaning towards replacing the compressor/clutch assembly, pretty sure that will fix it!

-- Carl