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Question on Compressor

sportsfreaked on Sat July 23, 2011 7:22 PM User is offlineView users profile

Year: 1996
Make: Chevy
Model: Corsica
Engine Size: 3.1
Refrigerant Type: 134-a
Ambient Temp: 90
Pressure Low: 45
Pressure High: 200

Last year I replaced the compressor on my wifes car. It worked fine untill a couple weeks ago. I had put in a new condenser and receiver. The clutch went out on the original compressor and a rebuilt was close to the same. The oil was good for a 14 yr old car anyway no signs of metal. I flushed the lines and blah blah blah. So a couple of weeks ago it was not cooling. I recovered the 134 and put a new TXV on vacuumed and recharged. The temp was about 90 in KC and I had a good high side reading of 200 but the low side would not go below 45. Vent temp of 50-55. All the same readings before I changed the TXV. I am thinking that the control valve on the V5 compressor is bad. The compressor is under warranty and they are sending me a new one. I am curious as to what you guys think. My wife use to work fom home so it was not a big deal but she now has a job in the office and her a/c has to work. The F250 diesel uses way to much fuel for a daily driver. The compressor and clutch seem to be working ok so I am thinking it is the compressor control valve.

I would also like to thank the people that have this forum. I did some a/c work in the early 80's when I was 18. Things have changed a lot! I am disabled from degenerative joint disease and have had 3 major spinal surgeries (fused entire lumbar), 2 elbow surgeries, and 4 knee surgeries with the 4th being a replacement. It takes me forever and a day to do anything and these types of forums help out a great deal. I just do not trust people working on my stuff! I have 2 sons that help me out when I need it. I try to help when I can on other forums for Ford Diesel trucks and a Camaro site. I will try to help here as well. I have a very basic understanding of the a/c most of which was learned from reading from places like this and books. I have the factory service manual for the car so it helps as well. Thanks again for any and all suggestions.

Do you think I need to flush the system again? It has been less then a year like I said and it does not appear to be a catastophic failure.

-------------------------
Thanks for the time

ED

Edited: Sat July 23, 2011 at 7:23 PM by sportsfreaked

JJM on Sun July 24, 2011 12:01 AM User is offline

I honestly don't know how you manange. It's great to hear that you've got such wonderful sons, I guess a job well done. I hope my boy wants to help out his old man when I get to old and feeble... already halfway there.

If anything, I think you might have a TXV issue, because if your control valve were the issue, your high side pressures would be lower.

First things first, let's see what your V5 can do... run the engine at 2,000 RPM and partially cover the condenser (or disconnect the fans) - be careful here. If the high side pressures get over 300-325 PSI, this test has been concluded - your V5 has passed.

It is possible the control valve is stuck open, but all that would cause is the evaporator to freeze up under low load conditions. We can do a quick test for that too. Run the engine at 2,000 RPM and disconnect A/C blower motor. The low side pressure readings should drop then stabilize, as the high side pressure readings fall like you've got a bad compressor.

To quickly test the TXV valve, carefully remove the sensing bulb from the evaporator outlet pipe, making sure not to kink or otherwise damage the capillary tube. Prepare a container of crushed ice and water (32ºF), and another container of hot water (approximately 125º or more). Start the engine and run it at 2,000 RPM, and record your pressures with the A/C on. At this point your low side will be high. Immerse the sensing bulb in the container of ice water, and the low side pressure should drop. Immerse the sensing bulb in the container of hot water, and the low side pressure should rise. If the pressures do not change, or change very little, the expansion valve is defective and must be replaced. Alternately, you can blast the TXV control head with hot and cold.

Joe

When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com

sportsfreaked on Sun July 24, 2011 6:47 PM User is offlineView users profile

Joe,

Thanks for the reply. It wasn't easy in the beginning on any of us especially my wife and kids. My boys were 4 and 2 when it all started to happen and I was 32. I am only 47 going on 80 lol.

I thought it was the TXV as well so I replaced that and vacuumed it down for 30 minutes and recharged and I had the same readings. That is what led me to believe that it may be the compresor control valve. I was following the factory manual "tree" and diagnostics. The test seem to point to the control valve. The compressor place said it sounded like it may have to much oil but I don't think it is that as I followed the book and only put a total of 9 oz of Pag 150 oil in the system. It sounds like the compressor is not pumping or a destroke according to the Chevy manual.

I guess I will wait for the new compressor to get here this week. I guess I have found a new place to order stuff thru! Forums like these really help folks out like me that 1. Don't trust other people to work on my stuff and 2. I really can't afford to take it somewhere to get fixed. My wife loves her 1996 Corsica and won't part with it lol. Usually we have vehicles that are in warranty so I don't have to work on them like our 09 F250. Thanks again for the time and the response. Will let you know once we get the new one on and going.


-------------------------
Thanks for the time

ED

JJM on Sun July 24, 2011 10:29 PM User is offline

It typically is not necessary to replace the whole compressor for a control valve issue - the control valve can be replaced - unless there are also other issues like the shaft seal and case halves leaking and you really don't want to bother with it anymore.

When you replaced the TXV, did you use an original GM part, or part sourced from the site sponsor? Also, did you make sure the TXV sensing bulb was firmly attached to the evaporator tailpipe, and the tailpipe was squeakly clean then properly insulated? I've seen sensing bulbs just shoved into the black goo and bewilderment why the system doesn't cool.

Also, when you replace the compressor, be sure to flush all the old oil out of the system, and add back the full 9 oz of PAG 150 and 36 oz of R-134a.

Joe

When considering your next auto A/C purchase, please consider the site that supports you: www.ACKits.com

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