Replaced cycling switch. What temp do you have at the vent?
#1
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Replaced cycling switch. What temp do you have at the vent?
When I got my truck the the cycling switch was bypassed and the compressor ran continuous. It would freeze in about 30-45 min of driving. On 100° day it would cool 40-50° on a 80° day it would get down to 15-25°. With the cycling switch installed intially it cooled to 40° and I'd be happy with that, but then it creeped up to 50° and stayed there. It was only about 11 am and I'd say about 80°. Without the cycle switch it would have been blowing much cooler. I've only had the switch in for a day. So I'll see what happens today. I was thinking about pulling the probe out some and see if that helps.
#3
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#4
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These trucks were designed for R12, the condenser and evaporators could be a little larger to keep the pressures down with R134a, but you still should be able to do better than 40. What is your high side pressure looking like with the truck running, warm and cycling?
#5
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#6
As a former service manager...I’m sure the compressor is weak if it is the original. Mine used to get in the upper thirties with r12 refrigerant. With 134a...best I ever got was 49 degrees.
#7
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It'll get down to 20 if it's 80 degrees out and I bypass the cycle switch, but it does take awhile to get there. Maybe the compressor is weak? If I replace the compressor, what other components should I replace?
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#8
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Check your pressures. I think you probably just need to add a can of R12.
#10
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Are the condenser fins all bent up and filled with crud? That can cause loss of cooling. I was getting 38 degrees from the vent on 134-a, on a very humid, rainy day in Mexico. IIRC the most you can get out of these ac systems is around 30-35 degrees below ambient temps...Mark
#11
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Are the condenser fins all bent up and filled with crud? That can cause loss of cooling. I was getting 38 degrees from the vent on 134-a, on a very humid, rainy day in Mexico. IIRC the most you can get out of these ac systems is around 30-35 degrees below ambient temps...Mark
#12
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It would probably go to ambient temp, if it doesn't cycle back on. I shouldn't cycle off at all, if the cycling switch is working and adjusted right and all other affecting conditions, like engine temps are relatively normal. In AZ, kind of a hot place, the ac never cycles off, on these old systems anyway. The new compressors on the newer vehicle are constantly running and cycling on and off. I like simplicity...Mark
#13
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It would probably go to ambient temp, if it doesn't cycle back on. I shouldn't cycle off at all, if the cycling switch is working and adjusted right and all other affecting conditions, like engine temps are relatively normal. In AZ, kind of a hot place, the ac never cycles off, on these old systems anyway. The new compressors on the newer vehicle are constantly running and cycling on and off. I like simplicity...Mark
#14
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https://www.dieseltruckresource.com/...t-t298318.html
#15
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I don't believe that they cycle on and off while they are above the set temp of the cutout switch. I could be wrong, but mine will run continuously and not cycle at all on a hot day (most summer days here). The new ones will, I think, but these shouldn't. I believe that freezing can be cause by a dirty and clogged evaporator coil, inside the car. It is a common problem especially if you live within 50 feet of a pine tree. the needles get in through the cowling in front of the windshield. Ask me how I know...Mark Edit: Check this thread:
https://www.dieseltruckresource.com/...t-t298318.html
https://www.dieseltruckresource.com/...t-t298318.html