AC broken

14Silverado50 · July 17, 2020

So my 14 Silverado has about 60k miles, belt broke between the crank and AC compressor. Found out the compressor was completely locked up. Replaced the compressor and expansion valve, new o-rings as well.

Brought it to get evacuated and recharged, and was told there’s no leaks. They put just under 2lbs in, but I still have warm air.

I only have a gauge that came on a Freon can, and the low side is way high, around 140. Compressor and clutch are both working fine.

Any ideas what the problem could be?

btj_z71 · July 18, 2020

36 minutes ago, 14Silverado50 said:

So my 14 Silverado has about 60k miles, belt broke between the crank and AC compressor. Found out the compressor was completely locked up. Replaced the compressor and expansion valve, new o-rings as well.

Brought it to get evacuated and recharged, and was told there’s no leaks. They put just under 2lbs in, but I still have warm air.

I only have a gauge that came on a Freon can, and the low side is way high, around 140. Compressor and clutch are both working fine.

Any ideas what the problem could be?

Are you sure you are plugged into the low side? Your low side PSI should be between 30-35 PSI. It's likely not turning on if the low side pressure is that high.

Next thing to check would be Schrader valves with leak detector.

edz71 · July 19, 2020

If your compressor lock up you you could a clogged condenser, it's always a good practice to replace the condenser and flush the system.

txab · July 19, 2020

1 hour ago, edz71 said:

If your compressor lock up you you could a clogged condenser, it's always a good practice to replace the condenser and flush the system.

^^^ +1

carnau · July 19, 2020

On 7/17/2020 at 7:55 PM, 14Silverado50 said:

So my 14 Silverado has about 60k miles, belt broke between the crank and AC compressor. Found out the compressor was completely locked up. Replaced the compressor and expansion valve, new o-rings as well.

Brought it to get evacuated and recharged, and was told there’s no leaks. They put just under 2lbs in, but I still have warm air.

I only have a gauge that came on a Freon can, and the low side is way high, around 140. Compressor and clutch are both working fine.

Any ideas what the problem could be?

No one is seeing the problem from what he said? lol

You have too much Freon in the system.

Your truck only holds 1.4lbs of Freon. If they put 2lbs in it, Your pressure are going to be way out of range and your system will not work correctly.

Take it to someone who can recover, vacuum and recharge your system correctly.

14Silverado50 · July 19, 2020

So I picked up a set of AC gauges. Both high and low side are about 108. If it were overfilled the high side would still be reading much higher, right?

Everything I read is pointing to a bad compressor, but it’s got a brand new AC Delco compressor. Clutch operates as it should, on when the AC button is on, off when it’s not.

Checked with a UV light, no leaks anywhere that I can see.

im pulling my damn hair out and I’m bald, so it’s tough

bdbake01 · July 20, 2020

Following as I seem to have the exact same issue. Been fighting it off and on all weekend. I think full charge is 29oz, but I never saw any differential across my compressor from 0 all the way up to 29oz, both high and low side topped out around 120psi and just sat there. Clutch works fine, but it doesn’t even seem to load up the engine when it kicks in.

Brand new condenser (the beginning of the issue), no leaks, held about -29psi for 2 hours. Doesn’t leak under charge either.

Not my first rodeo, this is my 4th condenser (one due to an accident), and I’ve replaced and charged them all. This time, I think the compressor bit it too

carnau · July 21, 2020

On 7/19/2020 at 6:17 PM, 14Silverado50 said:

So I picked up a set of AC gauges. Both high and low side are about 108. If it were overfilled the high side would still be reading much higher, right?

Everything I read is pointing to a bad compressor, but it’s got a brand new AC Delco compressor. Clutch operates as it should, on when the AC button is on, off when it’s not.

Checked with a UV light, no leaks anywhere that I can see.

im pulling my damn hair out and I’m bald, so it’s tough

No. Never diagnose your vehicle using static pressure. So many people make the mistake of using static pressure to "Know" whether the system is charged full or not. The static pressure in a vehicle will correlate to the ambient temperature outside. 108PSI is about 90 degrees outside (I make that knowing that 100 psi is 86/87 degrees ambient) If you buy diagnostic gauges it will actually show you this on the gauge setup (the temperature that is) But in general, static pressures in a vehicle are useless because if your system is overcharged you are going to see very minor increases in static pressure to ambient temp.

So, here is what I did. I charged a system to full. Today it was 98 degrees outside and 103 in the shop. After 20 minutes of letting it sit there charged, I looked at the static pressure. It was at 104psi. When I cranked the vehicle it ran at 35/200 which is fine with the humidity. Cooled to 41 degrees out the center vents.

I force charged another 0.50 lbs of freon in the system bringing it up to 1.90lbs. After 20 minutes of letting it sit untouched the static pressure was at 110psi. When I cranked the vehicle and let it run, It ran at 43/305 and kept cycling. Cooled to 68 degrees out the center vents.

Recovered and recharged the system to the correct amount and temperature was back down and cooling properly.

You can change your compressor if that's what you want to do. Just make sure they put the right amount of freon in the system this time and you will be back to running properly.

You keep saying you are pulling your hair out, But unless you put the wrong information in your primary post... The answer is right there. 2lbs of freon is too much. It's doesn't make it run any better with more freon in the system.

What is your high side and low side pressures at then the system is running?

bdbake01 · July 21, 2020

Update on my situation. Compressor was locked up, shaft sheered between clutch and compressor.

14Silverado50 · July 21, 2020

52 minutes ago, carnau said:

No. Never diagnose your vehicle using static pressure. So many people make the mistake of using static pressure to "Know" whether the system is charged full or not. The static pressure in a vehicle will correlate to the ambient temperature outside. 108PSI is about 90 degrees outside (I make that knowing that 100 psi is 86/87 degrees ambient) If you buy diagnostic gauges it will actually show you this on the gauge setup (the temperature that is) But in general, static pressures in a vehicle are useless because if your system is overcharged you are going to see very minor increases in static pressure to ambient temp.

So, here is what I did. I charged a system to full. Today it was 98 degrees outside and 103 in the shop. After 20 minutes of letting it sit there charged, I looked at the static pressure. It was at 104psi. When I cranked the vehicle it ran at 35/200 which is fine with the humidity. Cooled to 41 degrees out the center vents.

I force charged another 0.50 lbs of freon in the system bringing it up to 1.90lbs. After 20 minutes of letting it sit untouched the static pressure was at 110psi. When I cranked the vehicle and let it run, It ran at 43/305 and kept cycling. Cooled to 68 degrees out the center vents.

Recovered and recharged the system to the correct amount and temperature was back down and cooling properly.

You can change your compressor if that's what you want to do. Just make sure they put the right amount of freon in the system this time and you will be back to running properly.

You keep saying you are pulling your hair out, But unless you put the wrong information in your primary post... The answer is right there. 2lbs of freon is too much. It's doesn't make it run any better with more freon in the system.

What is your high side and low side pressures at then the system is running?

That was the pressure when it was running, clutch was engaged. Regarding the 2lbs, that’s what I was charged for. It was a shop that did the work evacuating the system and refilling it, I’d have to think they looked the specs up and just rounded it up when they charged me. Even if it were overfilled, wouldn’t the high side pressure be higher when it’s running and the clutch is engaged?

carnau · July 21, 2020

22 hours ago, 14Silverado50 said:

That was the pressure when it was running, clutch was engaged. Regarding the 2lbs, that’s what I was charged for. It was a shop that did the work evacuating the system and refilling it, I’d have to think they looked the specs up and just rounded it up when they charged me. Even if it were overfilled, wouldn’t the high side pressure be higher when it’s running and the clutch is engaged?

Both the high side and the low side are at 108 while it is running ans the compressor is engaged?

14Silverado50 · July 21, 2020

27 minutes ago, carnau said:

Both the high side and the low side are at 108 while it is running ans the compressor is engaged?

Correct

PPK · July 22, 2020

Back in the day... the old GMs.. ran A-6 compressors. they ran at high rpm, never overheated.. and when revved they were like 3 ton units.. cast iron and 6 pistons... fast forwarding... when i pass a vehicle.. i disengage my AC not to over-rev it or let it at high rpm for extended periods... once they let go... it is hard to get them back in shape without starting over with everything.. my experience...