A/C problem, compressor?? Help

[Runninglate]

Hi guys, I'm new here and I'm having an issue with my A/C.
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. It has always had a slight freon leak, even when it blew really cold air.
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)

The ambient air temp was 96 degrees and the humidity was 40%. Also, the compressor never cycles, it is constantly running.
Any thoughts on what could be wrong? Thanks!

 

[Goodinblack]

I do believe...... and someone correct me if I am wrong. That this model had a variable vane compressor that does not cycle but instead changes the stroke internally.

 

[Runninglate]

That makes sense. Should I have posted this in "general discussion"?

 

[Runninglate]

A/C problem, compressor??? Help

Hi guys, I'm new here and I'm having an issue with my A/C. I originally posted this in the wrong category by accident.

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. It has always had a slight freon leak, even when it blew really cold air.
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)

The ambient air temp was 96 degrees and the humidity was 40%. Also, the compressor never cycles, it is constantly running.
Any thoughts on what could be wrong? Thanks!

 

[orange57]

To be honest, I would guess your charge is still low. and you are not getting enough liquid refrigerant past the orfice tube to give the evap coils enough mass to actually cool the air.

I would suggest having the system completely evacuated, and flushed, find your leak and repair it, and then have the correct amount of oil put back in and the correct weight of refrigerant.

You were low enough to not allow the compressor to engage, so that means it was pretty low.

Were you measuring the actual temp coming out of the duct?

 

[Runninglate]

I added a decent amount of freon, should be close to full. But I know it's hard to tell unless the system is evacuated first. WHen it was 96 outside, the duct temp was low 80's when I was moving and heated up close to ambient temp while sitting at red lights. Even when it was cooling well, a few years ago, the low side pressure was higher than normal.

 

[orange57]

Clean your evap coil and see if that helps. There is a DIY on here somewhere. Your coil could be dirty.

 

[SunlitComet]

with that weather you should have had 290/32 with 63° out the center vent with engine at 1500rpm. your charge sounds way to low. are your gauge liquid filled?

 

[Runninglate]

I will clean my evap core today or tomorrow and see if that helps. As far as my gauges go, they are not liquid filled, they are from harbor freight. I'm contemplating just buying a compressor kit that includes a new orfice tube, compressor, o rings, dryer, and oil for $150. Not sure though

 

[SunlitComet]

then don't worry about the gauge flutter. try dealing with the refrigerant charge first.

---------- Post added at 09:09 PM ---------- Previous post was at 09:07 PM ----------

oh and a quality parts job with that list ain't happening for only $150.