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Topics regarding the climate control in the cabin of the van. Discuss things like air conditioning, refrigerant recharging, and dual climate controls, a/c vents, accumulator or defrosters, heater core, or fan inside the van.
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High pressure on the low pressure side

July 30th 2011, 5:14pm

Hello I am new to this site it looks nice.
2000 Astro Cargo Van / Front Air Conditioning only

I had a leak so after all else failed I removed the evaporator coil to see if the leak was in there. I used dye and a UV light. To keep it simple I put the system back together and now I have high pressure on the low pressure side equal to the high side.

Here is what I did wrong. I added 8oz of oil to the evaporator from the orifice tube and the rest I poured directly into the dryer. I did not drain the old oil so I am sure I have to much. I was careful to put the Orifice tube in the right way.

1. Do I need to remove the compressor and drain the system?
2. Can I use a flush and compressed air to clean the evaporator and condenser or do I need to remove them?
3. I never did find the leak so while I have it apart I am going to replace all the "O" rings - anything special I need to know here?
4. Anything special about the orifice tube.

Jim zxxx

Re: High pressure on the low pressure side

July 31st 2011, 1:22am

Orifice tubes are marked direction of refrigerant travel.Other than that no.Unfortunately if your not getting any pressure difference at all between high and low sides,Even with a shot orifice tube it should be some difference.Sounds like a compressor issue.If liquid got to it,oil from being overfilled for example.It slugged the pump and bent the valves.Ruined it.I would check the orifice tube again first it the easiest.See if it in right.

Re: High pressure on the low pressure side

July 31st 2011, 11:34am

Thank you, BUT that's not what I wanted to hear. :eek:

I plan on pulling the compressor to change the oil and flush the system as well as change the "O"rings;

is there a way I can bench test the compressor?

Re: High pressure on the low pressure side

July 31st 2011, 1:24pm

First are you sure it was kicking on the compressor? I dont know of any bench test for compressors.There other HVAC guys on here one of them may know something I missing.I am Pretty Fred Flintsyone some times(primitive).My only suggestion is if you going to take it apart anyway.Turn it over by hand and put finger over opening see if it doing anything.I just went and did that downstairs to a know good pump it does.May or may not prove anything I dont know but if it does nothing your sure it shot.Just off the top of my head unproven something to try.I would make sure pump kicking on while still in van running(clutch engagement)and make sure the orifice tube right.

Re: High pressure on the low pressure side

July 31st 2011, 7:33pm

Yes, I put a jumper wire across the LPS and the comp kicked in. I just don't want to buy a new comp when everything was working fine except for the leak. When I put Freon in the system it got cold, but when I put it back together, with what I expect was with to much oil, it failed to operate. I miss spoke when I said the pressure was the same on the HP/LP side. After I broke down and bought a set of gauges, and while attempting to install some freon, I found the LP/S was reading 100psi the HP/S was reading about 25-30psi.

So as it stands the LP/S is well above the HP/S.

Thanks, I'll keep you informed and I you think of any more ideas please let me know.

Re: High pressure on the low pressure side

July 31st 2011, 9:16pm

I'm at a loss ( not an HVAC guy ) seeing that when the system is stable, the pressure is the same on both ports. When the system is running, the high side is always above and beyond the readings on the low side...I can't see how the low side could have that high of pressure since it's the "suction" side of the system.

Did a little google searching and it seems like this is possible, you aren't the only one...but here's the link if you want to read the 1 page discussion.
http://acsource.net/acforum/viewtopic.p ... 80&start=0

I can't imagine what you could have done to cause it though, other than the oil. Perhaps putting oil in the dryer is the problem...there's dissicant in there to pull moisture from the air and if you didn't draw the system down with a vacuum before recharging it, that may have a part in the problem.

Re: High pressure on the low pressure side

July 31st 2011, 9:23pm

one quick read I just did at that site suggested checking the radiator for debris...a cause of high pressure situations, though I doubt it has much to do with your problem.
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