NEED HELP Ac Compressor clutch not engaging

[eutechnyx]

Ac has worked fine for the past 5 years, I was told by the previous owner that he re charged the system before I bought it (could mean it has a very slight leak, again that was 5 years ago). To give background on the vehicle the last thing I did was replace the Engine coolant temp sensor and thermostat with all Acdelco stuff. When I turn the AC on I don't hear the compressor clutch engage and of course nothing but hot air and no change in idle. I was going to attempt to add some freon to the system but before throwing any money at it I wanted to get your opinions on any fuses/relays/sensors to check first.

 

[Sparky]

One thing you could do is turn on the AC, then carefully give the clutch plate a tap with something to see if it then engages. If it does, then you may have a weakened coil, and/or need to remove the shim behind the plate to narrow the clutch air gap.

If it doesn't, then look further. I know some people have had pressure switch(es) act up.

 

[eutechnyx]

Well that seems like a quick test, I just want to work from the cheapest option to the most expensive if possible. So I'll give that a shot, I never really suspected the clutch itself since it never made any noise or acted up at all.

 

[gpking]

My coil failed at roughly 98,000 miles, this certainly could be the culprit. I wouldn't imagine it fails completely out of the blue, mine failed gradually over the period of a year. Very obviously slipping and making a horrific burning smell.
Removing the shim might buy some time, but I had no luck with that trick. I needed a new compressor.
You can test the resistance of the coil to see if it is still good, but you will have to look up the exact values for that.

After replacing my compressor, I still was having a/c issues with the compressor disengaging after 5 minutes of use.
I have since replaced the ignition switch and (knock on wood) have not had any a/c issues since.

Really, your guess is as good as ours without doing more troubleshooting. Could be electronic, could be mechanical, could be low R-134a.

 

[eutechnyx]

So, it's 120 degrees but after work today I figured easy test was check all fuses, they all look fine and I swapped the ac relay around with another relay and still no ac. I couldn't get under the truck today to try to tap on the front of the compressor as suggested but I'll try that next. The clutch in front spins freely when the truck is off (unsure if that's normal).

 

[Blckshdw]

With as many guys you know over there that work on their own vehicles, there's gotta be someone with a set of HVAC gauges. Would take a couple of minutes to hook them up and see what kinda pressures you're looking at, to know if your refrigerant is low or not.

 

[eutechnyx]

With as many guys you know over there that work on their own vehicles, there's gotta be someone with a set of HVAC gauges. Would take a couple of minutes to hook them up and see what kinda pressures you're looking at, to know if your refrigerant is low or not.

I actually found a friend with some gauges, the low pressure port is on the actual dryer itself it looks like right? High pressure is on the line?

 

[Mooseman]

I actually found a friend with some gauges, the low pressure port is on the actual dryer itself it looks like right? High pressure is on the line?

That is correct.

 

[jsheahawk]

Yep, the high pressure test port is under the plastic radiator cover. It's on the passenger side.

Definitely throw some gauges on it. Also try tapping the clutch to see if it engages. If you touch the front of the clutch with something ferrous, it will stick to the magnetized clutch if the coil is energized. If you end up needing to try removing a shim.

 

[eutechnyx]

So, checked the pressures with truck off and they were zero high and low side. Added some freon with oil (can upside down so the oil got in the system) and got the compressor to kick on and off every 5 seconds. I uploaded two pictures to show the pressures with the ac compressor off. It kept cycling and when it did the pressures would jump all over the place so I couldn't show a reading with the compressor on. I read somewhere that I should be closer to 150 ish with the system off so I assume I need to add more freon/oil? I know I should probably just have the system evacuated and charged.

 

[Sparky]

If it is that low I wouldn't just get it charged. You have a pretty good leak to be at 0, so, charging it probably won't last long at all.

 

[jsheahawk]

If it is that low I wouldn't just get it charged. You have a pretty good leak to be at 0, so, charging it probably won't last long at all.

Sparky is right. You need to address your leak. Once you find it, you need to fix the issue; hopefully it's just a failed o-ring. Did the refrigerant (R134a...not Freon) have a UV dye in it? If so, you can get a snazzy light and glasses to find out where it's leaking...because that's all slowly venting out of your system as we speak. If it didn't have dye, get one that does.

Also, if there was zero pressure in your system, it was at equilibrium with the atmosphere. That means that air and moisture from the atmosphere has entered your A/C system. That's bad. It will eventually ruin your system.

If you already have gauges, you're half way to having all the specialty tools you need to do this repair yourself. You just need a vacuum pump. I bought this one from Harbor Freight, and it has worked great. You must change the orifice tube and the accumulator since your system has been open to the elements. They soak up moisture and debris, so they're ruined now.

 

[eutechnyx]

Sparky is right. You need to address your leak. Once you find it, you need to fix the issue; hopefully it's just a failed o-ring. Did the refrigerant (R134a...not Freon) have a UV dye in it? If so, you can get a snazzy light and glasses to find out where it's leaking...because that's all slowly venting out of your system as we speak. If it didn't have dye, get one that does.

Also, if there was zero pressure in your system, it was at equilibrium with the atmosphere. That means that air and moisture from the atmosphere has entered your A/C system. That's bad. It will eventually ruin your system.

If you already have gauges, you're half way to having all the specialty tools you need to do this repair yourself. You just need a vacuum pump. I bought this one from Harbor Freight, and it has worked great. You must change the orifice tube and the accumulator since your system has been open to the elements. They soak up moisture and debris, so they're ruined now.

I am having a guy local to me vacuum the system, pressurize the system and find the leak. I guess once the leak is found then I'll replace the orifice tube and accumulator. He told me I shouldn't of caused any damage at all by the charging the system and running it for a few minutes hopefully he is right. Just ordered the AC delco accumulator and AC delco orifice tube which I'll replace once we find the leak of course.

 

[Mooseman]

Running it like that for just a few minutes it should be fine. Your guy will probably use a leak detector to pinpoint the leak. Hopefully it's something easy (unlike me where it was the evaporator in the dash )

 

[eutechnyx]

Running it like that for just a few minutes it should be fine. Your guy will probably use a leak detector to pinpoint the leak. Hopefully it's something easy (unlike me where it was the evaporator in the dash )

I hope so too man, I think mine was cause by me yanking on the ac line near where I had to pull the alternator out to get the thermostat housing out recently. I was pulling and bending that line.

 

[Blckshdw]

When I had to fix mine last year, the accumulator had some sort of internal leak, so the dye never made it to a place where I could see it. Fearing it could be the evaporator, I had a shop diagnose it for me. When they confirmed it was the accumulator, I paid them the diagnostic fee, took the truck home and did the repair myself.

 

[Mooseman]

For that diagnostic fee, you could buy your own leak detector. ~$50 at HF.

 

[eutechnyx]

Got the system vacuumed and pressurized today with no sign of a leak. So we filled the system with freon and some dye detector and will keep an eye on it. I have a hissing sound right around the accumulator area similar to what Carlton described so I'm going to keep an eye on that, only makes the sound when the ac is on and slowly quiets down after you turn the ac off.

 

[Mooseman]

Hissing is quite normal when you turn off the engine and pressures normalize between the high and low sides.

 

[jsheahawk]

Got the system vacuumed and pressurized today with no sign of a leak. So we filled the system with freon and some dye detector and will keep an eye on it. I have a hissing sound right around the accumulator area similar to what Carlton described so I'm going to keep an eye on that, only makes the sound when the ac is on and slowly quiets down after you turn the ac off.

Weird. It should be a sealed system, so you had to have a leak somewhere to lose pressure.