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A/C Problem

Briandl79 on Tue June 01, 2010 12:45 PM User is offline

Year: 2006
Make: Jeep
Model: Commander
Engine Size: 5.7
Refrigerant Type: R134A
Ambient Temp: 80
Pressure Low: 50
Pressure High: 250
Country of Origin: United States

So I had a problem with my A/C blowing warm. I thought it was low on refrigerant so I had the system evacuated, put a vacuum on it and recharged it. When I put a vacuum on it I did it for 30 mins, ten minutes to check for leaks, then 30 more minutes, then 30 minutes to check for leaks, then another 30 minutes under vacuum. I did it that way because the manual form my vacuum pump said 30/10 but some other information I found said longer to pull vacuum and check for leaks so I went ahead and did it longer for a total of an hour and a half under vacuum and 40 minutes to check for leaks.

It held the vacuum so I went ahead and recharged it. It's a rear A/C system that takes 34oz so I used three cans for a total of 36 ounces, but I figure with purging the lines, and having a bit of pressure remaining in the cans when I was finished that I probably got very close to 34oz.

The problem is that it still doesn't cool very well. With an ambient temp of 80 my vent temps are about 64 degrees, the passenger side is about 72, and the rear A/C is about 68. Other things I noticed or know: The compressor comes on, the high side is hot going into both expansion valves, but it seems that the low pressure line is much colder coming out of the rear A/C expansion valve than it is coming out of the front unit expansion valve. I did try to factor in that the front unit low side is right next to the back part of the engine, but I still believe that the low side line just isn't as cold and that it's part of the problem, or a symptom of it. The rear also sweats more and drops more water than the front does.

I'm thinking I might have a problem with my front expansion valve, thoughts?

TIA

bohica2xo on Tue June 01, 2010 12:53 PM User is offline

Was this an air operated vac pump?

What vacuum reading did you have before charging?

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Briandl79 on Tue June 01, 2010 12:55 PM User is offline

It was an electric pump. It went as far back as the gauge would go, 30HG.

Peter_Coll on Tue June 01, 2010 1:02 PM User is offlineView users profile

What was in the 3 cans??

Briandl79 on Tue June 01, 2010 1:04 PM User is offline

Just R134A, but I'd previously used a synthetic that had some other additives. I tried that one but I had no idea what I was doing so I figured I'd get gauges and a vacuum pump and try to do it right.

bohica2xo on Tue June 01, 2010 2:36 PM User is offline

At first glance, your system pressures looked like it had air in it - that is why the vacuum questions.

Now the issue of additives / too much oil becomes the likely culprit.

The differences between TXV's could be evaporator airflow / capacity, or a somewhat plugged TXV. Since you will need to open the system to check the TXV, you might as well flush the components to bare metal & start over with a known volume of oil & a clean system. Replace the dryer while you are there.

You own the tools already, which is great. Doing it right is not that hard, but it is worth the effort.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Briandl79 on Tue June 01, 2010 9:08 PM User is offline

I'm not sure it has too much oil, or at least it didn't at first. Initially I put in just one can of refrigerant and that's why I noticed the problem with the high pressure readings. I thought somehow it was possible that I overfilled it so that's why I had it evacuated and refilled with the exact amount of refrigerant. Unfortunately I did use (and maybe I shouldn't have) a R134A with 1oz a few different things including oil, three cans for a total of three ounces. So if I do have that problem now I didn't in the first place, which is why I figured TXV.

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