May 4, 2014 at 7:07 pm #6696
Preliminary checks have turned up the following:
– The A/C dashboard button light responds to input (turns on and off by pressing button)
– The compressor itself turns freely by hand and the belt is new and appears to be spinning freely with no noise (bearings are good)
– I pulled the lead to the A/C compressor clutch and get 0 volts when engine is running, fan on and A/C dash button pushed (and glowing).
– Only fuse I found is on right side of engine bay. Checked 10A fuse and it is fine (0 ohms resistance).
– I am getting 12+ volts to the fuse (mentioned above)
– With engine running and A/C dash button turned on, the engine will not change RPM.
– Radiator fans are functioning correctly.
I can’t figure this out. It must be something electrical between the fuse and the compressor clutch. Any ideas where to look?May 19, 2014 at 7:40 pm #6706
Test the clutch by giving it 12v to the lead while the engine is running. A good clutch will start pulling. If that’s the case it’s probably low on coolant. Check for any oil seepage on the bottom of the compressor. You may not get 12v by pulling the lead because there’s a low pressure switch that will not turn the clutch on when refrigerant is low.May 19, 2014 at 8:18 pm #6707
Thank Oldman. I had the same thought. I was also thinking of trying to jump the low pressure switch across the white and brown/yellow leads. I will provide an update.June 25, 2014 at 8:16 pm #6729
Turns out the A/C system has a leak. Jumping the bypass did not reveal this. I had to jump the compressor clutch to engage it manually. That allowed me to get pressure readings on the low and high side. Adding r134A got it working again but after several days the pressures drop and vent air becomes luke warm.
Next order of business is find the leak. Does anyone know if the detection dye you buy at the auto parts stores can be seen with anything other than ultra-violet? I have LCD lights but don’t know if that will work.July 5, 2014 at 11:17 pm #6733
Most of the time the leak is from the valve. The dye is ultra violet only. I use a kit from interdynamics that includes the UV light and glasses as well as the dyes and cleaner. Makes it really easy to see the leak and clean when done.July 10, 2014 at 11:49 am #6734
The light I have (LED) seems to work very well with the dye I bought, based on a quick test I did. So you mention a valve. There at least 3 that I am aware of, the front and rear expansion valves, 1 per evaporator, and the pressure relief valve on the compressor. The compressor checks out. So I assume it one of the expansion valves, buried somewhere under the dash or behind the interior panels in the back of the van. Fun!
Thanks for the tip on where to look.July 29, 2014 at 8:54 pm #7101
Well I found the issue, right under my nose. A simple $3 valve core for the high pressure line. I ended up replacing both the high and low side. After 1 hour on the vacuum pump, I refilled with ester oil and about 900 grams of R134-A. I forgot how cold the A/C can get in this thing.
On to the next project – front wheel bearings. Not bad for 135K. Most of these go before 100K. The power steering pump will have to wait.
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