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Clutch Coil issue

static on Fri July 10, 2015 7:17 AM User is offlineView users profile

Year: 2000
Make: Mitsubishi
Model: Pajero
Engine Size: 2500
Refrigerant Type: R134a
Ambient Temp: 28
Pressure Low: 45
Pressure High: 200
Country of Origin: Trinidad and Tobago

Hi Guys,

I have a universal 508 compressor installed for 5 years now. The problem is that if i am in traffic or parked up during the hotter part of the day the compressor eventually stops working. When i check the clutch is not engaged - hot air.
Quite often once i get out of the traffic and start driving the compressor kicks on, the time for this to happen varies though.

I poured some water on the pulley area when this happened and the clutch engaged after about 5 secs, it worked for a few mins and then it stopped again. My conclusion was that the clutch coil was heating up.
I thought it could be a current problem so i added a relay on the compressor wire. this did not have any impact.

The question is, do i just replace the clutch coil or the compressor based on the fact its been 5yrs?


GM Tech on Fri July 10, 2015 8:46 AM User is offline

Never seen your "coil heat up" theory before-- better chance your airflow across condenser is low- as in fan speed or clutch fan issue- spray the water on the condenser, not the compressor next time. Also, put a set of gages on it, to talk more intelligently- you are most likely having high pressure cut-outs- which is trying to keep you from blowing out your hoses...

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

static on Fri July 10, 2015 10:26 AM User is offlineView users profile

Thanks GM Tech

I know this is a strange one, the compressor in the my Honda Civic has both a pressure release valve and a cut off, however this universal compressor does not have any of these, i confirmed this at the shop i bought the compressor also.

I am going with the theory of the electromagnetic getting weak due to overheating, probably a problem with the windings in the coil.


mk378 on Fri July 10, 2015 12:21 PM User is offline

Try making the air gap between the pulley and the plate smaller. This is done by taking the plate off and removing shim washers from the shaft, then reassemble.

It is normal for any coil to weaken as it gets hot because the resistance of copper wire increases with temperature. If the gap is critical you will get inconsistent engagement especially when hot.

static on Mon July 13, 2015 8:18 AM User is offlineView users profile

Problem Solved!

Thanks mk378 for your reply.

The issue turned out to be corrosion. The clutch coil fits in place via a dowel and is held by a snap ring. The vehicle had gone through some flood waters and the dowel and snap ring had some rust. This seems to have been causing a grounding issue. I cleaned all the surfaces with a mini wire wheel rotary tool and re-assembled.

Strange thing is that i disassembled another universal compressor i have and the coil is held by 3 screws. This is obviously the better design.


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