A/C problem, compressor??

[elliomcmh]

Hi,
I have a 1998 Yukon 4x4 with rear a/c. Ever since I purchased it 11 years ago, the a/c has slowly been getting worse; And has always had a slight leak.
It was tolerable until last year when the front and rear a/c started blowing hot air.
This year, I added a little freon (it was low enough that the compressor wasn't spinning), and the front a/c started working. It only cools the air about 10-15 degrees below the ambient temp when at highway speeds. It barely cools at all while at idle. The rear doesn't blow hot air anymore, but instead blows ambient temp air.
I cleaned out the condenser as good as I could by spraying it with water, but that didn't help my problem.
I hooked a set of gauges up to the Yukon and my readings are as follows:

- Static(engine off): high side 120, low side 115
- Idle speed(600rpm): high side 145, low side 74 (both needles were fluttering heavily)
- 1500 rpm: high side 160, low side 48 (needles were barely fluttering)
- 2000 rpm: high side 155, low side 42 (no fluttering)

Any thoughts on what could be wrong? Thanks!

 

[Slammed]

You need to evac and recharge system with the dye so you can see where it's leaking the most common areas are the high side Schrader valve and the upper pipe from the front to rear (under passenger side frame rail) and then the other spot is right rear behind wheel well going into the can that's there

 

[elliomcmh]

Ok thanks. I think I found the leak- low side Schrader valve. But I will check those areas too. Any ideas why my gauge readings are so crazy? Thanks

 

[elliomcmh]

I also forgot to mention that my compressor stays running the whole time and never cycles off. I guess this is due to the fact that the high side pressure never gets high enough or the low side pressure never gets low enough????

 

[Slammed]

I'm positive it is the leaks

 

[elliomcmh]

Could the compressor be leaking as well? I've heard these are prone to belly leaking?

 

[lesterl]

How hot was it outside, the low is kinda high for how low the high is....

 

[elliomcmh]

I forgot to add that part, it was 96 degrees outside, and 40% humidity

 

[elliomcmh]

Any ideas as to why the gauge readings are so far off?

 

[Slammed]

Did you fix the leaks? If you did you have a blockage do a 45 min recover vacuume

 

[elliomcmh]

I'm not sure if I fixed them or not. I fixed one. I'm about to go have it professionally inspected for leaks and try and get a diagnosis. The shop also evacs, weighs the freon that's in it, pulls a vacuum, and re/charges it with what was in my system. Not bad for $49.99. Hopefully I'll have more answers today

 

[elliomcmh]

Just had it professionally evac, recharged, and they used leak detector. He said that the reed valves were messed up and that the only leak was a small leak at the compressor itself. I guess I'm going to order a re-man compressor kit.

 

[elliomcmh]

Tonight I Installed a new compressor and orfice tube, from auto zone. I was going to replace the dryer too, but the line closest to the firewall was seized and wouldn't budge. I pulled a vacuum, and placed 44oz of 134a and 11 oz of oil (as stated on the sticker on the dryer). My front a/c is now great (41 deg center vent at idle). However, my rear air temp was 74. The ambient temp was 78 at the time. My low side was 25 psi and my high side was 175 psi at idle. Any idea why my front vents are blowing ice cubes, but my rear ac is only a tiny bit below ambient temp? Is 44 oz the correct ammount of freon for a 1998 yukon with rear air? Thanks

 

[Slammed]

The amount is written on the front by the passenger firewall

How did they test for leaks because mine passed every time but it wouldn't last a week so I had them do the dye test they found 5 leaks the only way the rear wouldn't blow cold would be either a blockage or leak or wrong amount of freon

 

[elliomcmh]

They used a "sniffer". I've seen online where that 44 oz number is too low, and it really holds more like 64 oz. Based on my gauge readings, that may be true.