1997 Ram diesel, high suction pressure, low discharge, need help

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12valve
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Joined: Thu Aug 03, 2017 11:18 pm

1997 Ram diesel, high suction pressure, low discharge, need help

Postby 12valve » Thu Aug 03, 2017 11:46 pm

In a nutshell:

Compressor was short-cycling, 1 second on, 2 seconds off, constantly, no cold air. The static pressures were equal on both sides, but when I started it up I had as high as 90 on the low side, but only 125 max on the high side, dropping down to 90 when it cycled. Ambient temp outside was roughly 75.

I tried to add refrigerant through the low side (through my manifold gauges) to see if I could slowly bring the high side up, to no avail. I evacuated the system, and pulled the orifice tube. It was clean. I found evidence of refrigerant oil at the manifold hose assembly connection to the compressor, so I replaced the sealing washers. I put the system in a vacuum, and it held 28Hg for a few hours.

I then tried to charge off a can into the low side, but it will not take it, maybe only an ounce or two. I had made sure to carefully purge all lines of air before I did. When I open the low side valve, my gauge will rise to nearly 100 psi, but almost no refrigerant enters the system, like there's a restriction in the low side preventing any refrigerant from going in. When I jump the compressor it will not draw it in. I have verified that the schrader is indeed being pressed. I have to turn it off because it starts getting hot.

Am I dealing with a compressor which won't pump? The fan clutch pulls air hard. I can put a rag in front of the condenser and it sticks to it. I have the blower on high and the ac on max. There are no gross leaks as I've had the truck 4 years and it still had some refrigerant in it. I am willing to buy a compressor if need be, but want to make sure that's my problem. Any help is greatly appreciated. Thank you.
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Tim
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Re: 1997 Ram diesel, high suction pressure, low discharge, need help

Postby Tim » Fri Aug 04, 2017 9:23 pm

No control valve in this model compressor. So if it not pumping and clutch engaged, dead compressor.
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12valve
Posts: 2
Joined: Thu Aug 03, 2017 11:18 pm

Re: 1997 Ram diesel, high suction pressure, low discharge, need help

Postby 12valve » Sat Aug 05, 2017 8:35 am

Thanks for the reply. It ended up being faulty equipment. The low side hose on my brand new Chinese FJC manifold gauge assembly had a complete blockage where the washer/gasket was supposed to be. It would intermittently feed pressure back to the gauge, but not accept refrigerant. I had ended up charging the system through the high side with the vehicle off and the refrigerant in a bucket of hot water. I finally took the gauges apart and found, to my disgust, the problem.
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Tim
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Re: 1997 Ram diesel, high suction pressure, low discharge, need help

Postby Tim » Sat Aug 05, 2017 9:06 am

Good deal. Cheaper than a comprssor replacement.
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