AC Problems Help!

TopazSilverado21 · August 19, 2017

Ok long story but here goes...

Noticed ac was getting warm. Hooked up handheld gauge and pressure was low. Compressor was working fine. Filled with R134a up to proper pressure. Ac works fine. 2 days later, same issue. Took it to a shop and found out there was a crack in the condenser. Quoted me $800 to fix it. Said forget it and ordered the part myself. Installed at home. When done, took it to the ac guy and had him evacuate and fill the system. Called me an hour later and said your compressor clutch is not engaging. Weird because that was never an issue before. Took the car home and here's where things get weird.

Got home and opened the hood. Noticed that the radiator fans were running loud as hell and the clutch was not engaging. Hooked up the gauge and pressure was reading through the roof on the low side port. Had a buddy come over and take some refrigerant out and the compressor clutch immediately kicked on working fine. Radiator fans immediately slowed down and car was no longer as loud. Still no cold air. Hooked my gauge up to the low port again. Pressure read low. Turned the car off, about 10 minutes later turned back on and car was running loud as hell again and pressure was through the roof. Removed some more refrigerant and car quieted down, no cold air and clutch engaging.

Fast forward to this morning. Thought maybe the guy overfilled it. Started the car and pressure was low. Went over to auto store and connected the R134a can to it. Started filling it. Pressure would climb when adding the refrigerant but then fall again. After about 5 seconds adding it, engine got really loud again, clutch disengaged and pressure reads extremely high.

Any ideas? Still no cold air

LongrangeLauber · August 19, 2017

Maybe a clogged up orifice tube?

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bdbake01 · August 19, 2017

Maybe a clogged up orifice tube?

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Kinda what I was thinking. You've got something plugging up intermittently.

TopazSilverado21 · August 19, 2017

Where is the orifice tube located?

LongrangeLauber · August 19, 2017

That I couldn't tell you on these k2 trucks lol

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TopazSilverado21 · August 19, 2017

From my research and contacting local auto parts stores, the 2014 Silverado doesn't have an orifice tube but an expansion valve? Same thing?

Spurshot · August 19, 2017

Sounds like the ac guy is messing with you. Find a different guy or buy a vacuum pump. You need a real set of gauges a thermometer and a vacuum pump, as a minimum to recharge a system.

The orifice is located in the block where the lines go into the firewall. There are two screws holding the block on.

There is no way to really know what's going on until you evacuate the system and refill with the correct amount. It could be overfilled with freon or oil.

Edited August 19, 2017 by spurshot

TopazSilverado21 · August 19, 2017

Sounds like the ac guy is messing with you. Find a different guy or buy a vacuum pump. You need a real set of gauges a thermometer and a vacuum pump, as a minimum to recharge a system.

The orifice is located in the block where the lines go into the firewall. There are two screws holding the block on.

There is no way to really know what's going on until you evacuate the system and refill with the correct amount. It could be overfilled with freon or oil.

Understood, but you think it would still be over filled if we took a bunch out? The system right now shows low pressure. As soon as you start adding refrigerant, the engine gets louder and the gauge jumps to max pressure and the clutch disengages.

When I took it to the shop after replacing the condenser, the guy said he evacuated the system, checked for leaks, and then filled with the proper amount. That's when he noticed the clutch wasn't engaging

Spurshot · August 19, 2017

Pressures are not meaningful unless the compressor is running and you have the temperature of the air blowing over the condenser. "Low", "high", etc., can't be used to diagnose. You need actual high side and low side pressures simultaneously while running with the compressor engaged.

Edited August 19, 2017 by spurshot

Spurshot · August 20, 2017

Adding freon with the compressor running requires care to prevent "slugging" or introducing liquid freon and hydraulically locking the compressor. Tipping a can upside down can be a problem. If you aren't familiar with servicing ac systems, a good book on the subject is worth the time.

Justin101714 · August 20, 2017

Kind of hard to mess an TXV up these days. Orifice tubes worked well, but failed consistently. Look at the rubber on the front of the compressor make sure it isn't starting to look like it's melting. Also, if you don't have a way to get gauges on the high and low side ports, it's hard to figure out what's going on. Go grab yourself some gauges from harbor freight or something. Let us know what the pressures read at idle and give the ambient temperature as well. Make sure you don't have any fluctuation in the needles when the compressor clutch is engaged. This would signify a bad compressor.

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Spurshot · August 20, 2017

Having a thermometer you can stick in the vent is valuable in figuring out what's going on too. One of the IR gun thermometers will let you measure component and line temps.

With a set of gauges and thermometers, you should be able to see what's going on. The wild card is not knowing how much refrigerant is in the system, since you've bled off and added. If you knew you had the correct charge, pressures and temps will give a clue to a problem. The symptoms you gave could be an overfill or a sticky TXV. But without vent and component/line temps and high and low side pressures, it's a crapshoot.

zmnypit · August 21, 2017

Kind of having the same problem. I noticed last week my AC wasnt cold but then it started working again so I wrote it off. Go on vacation and get back yesterday and go to move my truck and its hot again. Today its all hot and a loud fan. I tried a recharge before we left and it seemed to work. Guess I'll check for the dreaded condenser leak later today.

TopazSilverado21 · August 26, 2017

Kind of having the same problem. I noticed last week my AC wasnt cold but then it started working again so I wrote it off. Go on vacation and get back yesterday and go to move my truck and its hot again. Today its all hot and a loud fan. I tried a recharge before we left and it seemed to work. Guess I'll check for the dreaded condenser leak later today.

Yeah mine stated the loud noise after I replaced the condenser. I kept losing freeon when I found the crack

zmnypit · August 28, 2017

Yeah mine stated the loud noise after I replaced the condenser. I kept losing freeon when I found the crack

No leak in mine. Took and had a recover/vac/recharge done and no signs of a leak. While searching the temp never would get below 60* in the vents on low. 3 days later its still working and hasnt quit yet, however it doesnt get below 60*. The mechanic pulled some HVAC codes that Im not sure exactly what they mean.

B1325 Control Module Power Circuit

B0413 Main Temperature Control Feedback Circuit

U1509 LIN Bus 9

U0020 Low Speed CAN Bus