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Stumped on leak and high press

Dave5701 on Tue July 23, 2013 10:46 AM User is offlineView users profile

Year: 05
Make: chevy
Model: ssr
Engine Size: ls2
Refrigerant Type: 134
Ambient Temp: 90+
Pressure Low: 35-45
Pressure High: 275-375

Took AC class couple years ago, now I have to fix all my buddies stuff. Problem is I dont do this everyday and forget what I learned. One buddy has 2005 SSR. AC works but has a leak I cant find. Shop worked on it before and could not find it. We are now at a can of 134 every month. Some things seem odd to me. Engine is warm and outside temp is in the 90's. When charged up (both after getting it to blow cold and a schrader valve replacement, vac and 134 replacement). Low side cycles between 35-45 and high side is 275 to 375. Seems high to me on high side. Dye has been added and that is how I found the schrader valve leak. Thought that was it. Nope. Black light shows nothing I can find anywhere but I cant get to evap or condenser easily. I wonder if since pressure so high on high side, do I have some kind of blockage and that is why it is high. Dont seem to cool as well as it has before. System uses an exp valve and I did not work with one of those in class. Can those be cleaned out? Do I need to pull it and how do you flush it? I was thinking maybe flush the system, clean valve, tighten everything and see what happens. Any ideas?? OH, the high pressure fitting does not seem to have a schrader valve. IT looks like a black plastic cap in there, what is that??

GM Tech on Tue July 23, 2013 1:26 PM User is offline

Valves always appear green with dye--from the disconnect process-- high sides use a ball valve- no schraders there. your leak shouldbe easy to find- if and only if you can see the dye- so assume you can't get to the part that is leaking without tearing things apart. Check evap drain tube for dye spatters- as well as compressor case halves and shaft seal. Flushing will not solve a leak issue- txv's will work just fine if you have proper charge.

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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......

Dave5701 on Tue July 23, 2013 1:43 PM User is offlineView users profile

What is your opinion on the high pressure side going up to 375? I would not think it should go that high.

iceman2555 on Tue July 23, 2013 9:59 PM User is offlineView users profile

The high side pressure could be acceptable....considering the ambient temp and possible humidity. Check your fans....it appears they may not be functioning. Typically they should operate and maintain a lower high side pressure. However, the stated low side pressures do not correspond to the indicated high side pressures.
If the system has been leaking and refrigerant has been constantly added to the system...there is a serious problem with excessive refrigerant....possible excessive lubricant (has any been added) and possible internal compressor damage due to a improper lubricant balance due to lack of refrigerant. This could explain the excessive high side pressures. Is the high side port located on the discharge line (between compressor and condenser) or liquid line (between condenser and TXV/Orifice Tube). If located on the discharge line....there is a very good possibility of a condenser inlet restriction. IF this is valid...the condenser should be replaced. Test the line by testing temps....use your finger tips....touch do not grab....monitor for several minutes...if the temp continues to climb...to the point where it is too hot to touch...this would also indicate a possible condenser restriction.
Best bet...have the system recovered....evac and recharged with the correct amount of refrigerant utilizing the correct charge equipment. This would be the first step suggested.
This is a scroll compressor and very susceptible to damage due to improper lubricant balancing.
Good luck !!!

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

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