Automotive Air Conditioning Information Forum (Archives)

Leeroy on Sun September 02, 2012 9:23 AM

Year: 1999
Make: Chevy
Model: Silverado
Engine Size: 5.3L
Refrigerant Type: R134
Ambient Temp: 85 ish
Pressure Low: 120 ++
Pressure High: 200
Country of Origin: United States

I am stumped.

About 2 weeks ago I replaced the compressor accumulator and orifice tube on a friends truck. The system worked fine for about 2 weeks. He called and said that it stopped working. I figured I had a leak and told him to bring it back. No leak!!
The low side pressure with compressor running (jumper wire) goes up into the "retard" section of the gauge...somewhere north of 120. The high side goes up to 200-225. Obviously, the compressor is not running unless I jump it. When it is jumped, the air from the vents is cold. I replaced the orifice tube and this had no effect. I put 2 lbs of freon in the system. On a hunch, I put a large blower in front of the condenser and wet the condenser. So much for my hunches, as this had no effect.

Where do I go from here? Break the system down again and re flush? The parts are under warranty from Advanced, so I am only talking about labor, but that sucks too. I just wanna get this thing fixed.

mk378 on Sun September 02, 2012 9:35 AM

There's no way the air can get cold with those pressures. You must be measuring wrong.

Most likely it is just a bad cycling switch.

Leeroy on Sun September 02, 2012 10:51 AM

I checked my gauges on 2 other cars and they seem O.K..... They only hook up one way. When I "fixed" it a couple of weeks ago they read normal hooked up in the same positions. I am not arguing, just confused. I am not ruling out user error. Is there a way to test the cycling switch? I am jumping at the relay in the power distribution box.

You are talking about the one on the accumulator right????

Leeroy on Sun September 02, 2012 11:23 AM

O.K> I am going out to check the cycling switch. I will jump across and see what happens. I will report back as to what happens. I am going to ignore the pressures for now!!??

Leeroy on Sun September 02, 2012 1:26 PM

Jumping across the cycling switch produced no results. Well, almost none. The engine rpm goes up slightly but the compressor does not engage. Any ideas?

iceman2555 on Sun September 02, 2012 1:44 PM

What is the production date of this vehicle? Does this vehicle have the top mounted compressor or this an HU6 (low mounted) unit. Also, please state why the system had to be repaired and what procedures and a list of all parts replaced.
How was the system flushed, what chemical was utilized and how was the system recharged. Post as much repair/test info as possible. Also please attempt to measure the evaporator and inlet and outlet temps.
Thanks,

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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

GM Tech on Sun September 02, 2012 2:59 PM

Quote
Originally posted by: Leeroy
Jumping across the cycling switch produced no results. Well, almost none. The engine rpm goes up slightly but the compressor does not engage. Any ideas?

You don't jump across the switch-- you jump the connector that plugs into the switch

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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......

efxengr on Sun September 02, 2012 4:52 PM

gauge valves closed, right?

Leeroy on Sun September 02, 2012 5:11 PM

O.K.....I am officially an idiot. Thanks to all for your help.
This was a 2 stage problem
1.) Blown ignition fuse wiring diagram has it labeled as IGN E. (Yeah thats right a blown fuse). This was the main problem. I checked the AC fuses before I started. Didn't think to check the ignition fuses. Lesson learned. This circuit energizes the AC relay circuit.
2.) I hate to admit this, but since no one knows me I will tell you. efxengr was right. I forgot to close the gauges (color me embarrassed)

Thanks again guys.

efxengr on Sun September 02, 2012 7:35 PM

I learned that one the hard way.

Just think how good you felt when you closed the valves and it squared up, doesnt get any cheaper than that.