2002 silverado 1500
5.3, 310k miles

The a/c was working when I purchased the truck. One of the service ports was leaking last year, so I replaced it and the a/c hasn`t worked right since. So today I am trying to fix it. Static pressure was the same when I started, around 120ish if I remember right. I ran the vacuum on it for an hour and it was holding a vacuum.

So I started adding a can r134a and after most of the can was in the pressure on the low side started going up at a much faster rate then the high side. After one can is added, the low side is almost maxed on the gauge and the high is around 150 or so...

I am not sure if the compressor is turning on or not...Honestly I cannot remember ever hearing it kick on. My power steering whines so it makes it difficult to hear lighter noises. Any ideas on what might be the problem? Also how do I check the compressor and all the switches?

Thanks for any help...

 

The pressure is higher if the compressor is not turning. You can put a jumper wire in the low pressure connector to kick it on and get it filled to spec. If it won't come on by itself, the switch may be bad or have corrosion on the terminals.

BTW 310k is impressive!

 

The low pressure switch is the one on the accumulator that is on the firewall right? I tried jumping that already, but with the pressure high...I will probably bleed some out today and try to jump it again...How can I tell if the compressor is bad?

 

a restriction can also cause high pressures

 

Yes low pressure is near the firewall and high is down under and behind the headlight area. The pressure will drop when the compressor comes on. If it won't come on, tap on the relay. I know how you feel. I went about 2 years with no AC and I finally had to get the evaporator core replaced because there was a hole in it. That was lots of fun!!

 

Well I dont think it is that bad...it was working when I bought it, but it would always blow warm air if sitting still. Then I changed out the service port and put a can of r134 in and it was working just not as good. Then it just started getting warmer and warmer towards the end of the summer last year.

I dont know if it matters, but when I would be stopped or going slow the truck would start to overheat until either moving again or shutting off the a/c last year. At the end of summer it would get to the point even if I was on the highway it would overheat with a/c. This year I have not had any issues with overheating, but a/c hasnt been working. Thats why I was thinking it might be the compressor going out...

 

I bought it 1.5yrs ago with around 260k miles. The previous owner said its on the 3rd transmission, but untouched original motor. its been pretty good so far for a $2k truck. The body is in decent shape, except for some rust in drivers side rocker...

 

OK, so I lowered the pressure to 50 on low side port(which lowered it on high too) while the truck was running. The lower belt tensioner for the a/c was real wobbly and barely turned so I replaced that and the belt. Now there is a very faint marble in a jar sound when the truck is running that I dont remember hearing before...I have no idea why the belt wasnt slipping and making noise with how messed up the tensioner was.

After doing all that, I dont think the compressor is kicking on. I tried jumping the wires that go to the accumulator and the engine rpm would change just barely, but the compressor did not move at all on the inside. When I had all the belts off I moved the compressor and the outside and inside moved freely...Could the marble noise mean the compressor is bad? Any ideas?

 

I would think the high pressure switch or the compressor is the fault. Since you say you had a result in jumping the high pressure switch, I would replace the compressor

 

I am pretty sure the one I jumped was the low pressure...how do I check the high pressure switch?