A/C Issues and questions... Scratching my head
#31
06-13-2021, 03:16 PM
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The low pressure side is basically the suction side of the compressor though, It's sending all it's pressure out to the high side and the refrigerant is getting sucked back in through the low side. Both sides can EASILY handle 200+ psi, when you're pressure testing the system you open both the high and low side and fill everything to 200+ psi. If it's building pressure on the low side like that but the high side isn't moving it's almost always an internal failure on the compressor.
You can test for blockage pretty easily though, disconnect the compressor line set, hook the manifold back up to both the high/low sides, put air or nitrogen on the suction side of the manifold then open the low/high side one at a time. It will blow out of the compressor line set, use your thumb (with a glove if using nitrogen because it can get really cold really quick sometimes) to cover up the lines one at a time and let the air blow out of the other line. If you can't hold your thumb over the line then there is blockage somewhere. Remove lines and blow them out with air one at a time to find out where it's at.
I've seen expansion valves break and send pieces down the line which can clog it up.
If the line blows air out both sides then the problem is the compressor.
You can reuse the lines but they need to be washed out very well to remove all the metal. You'll never get the metal out of the condenser/evaporator so don't bother. The dryer is a wearable item that usually gets replaced with every compressor swap anyways, plus they're cheap. Usually the entire kit will cost like $400-500 unless you have the condenser that is built onto the radiator then it's an extra $150 or so.
You can test for blockage pretty easily though, disconnect the compressor line set, hook the manifold back up to both the high/low sides, put air or nitrogen on the suction side of the manifold then open the low/high side one at a time. It will blow out of the compressor line set, use your thumb (with a glove if using nitrogen because it can get really cold really quick sometimes) to cover up the lines one at a time and let the air blow out of the other line. If you can't hold your thumb over the line then there is blockage somewhere. Remove lines and blow them out with air one at a time to find out where it's at.
I've seen expansion valves break and send pieces down the line which can clog it up.
If the line blows air out both sides then the problem is the compressor.
You can reuse the lines but they need to be washed out very well to remove all the metal. You'll never get the metal out of the condenser/evaporator so don't bother. The dryer is a wearable item that usually gets replaced with every compressor swap anyways, plus they're cheap. Usually the entire kit will cost like $400-500 unless you have the condenser that is built onto the radiator then it's an extra $150 or so.
I bought the car in December of 2017. I didn't even really attempt to use the A/C until March or maybe April, at that time, it worked well enough, because it wasn't really hot out. Around mid-May 2018, I took it to a shop and they suggested the compressor, and I had it changed.
From there, the car generally had a myriad of other issues (starter, battery, transfer case, alternator, etc) , but the A/C functioned okay for the rest of the summer. In April 2018, the water pump failed and I bought a second vehicle which I drove most of the summer, but the AC in this car was not functioning and again the compressor was tagged as the culprit and it was changed again.....After that, the A/C functioned marginally, but would often make the car overheat especially at idle, (fan was changed during the water pump job)...I essentially parked the car until it got cold out and drove it all winter, then I changed the condenser last June and the overheating went away and the A/C worked okay, but not great....
Then I recently found that the condenser was leaking and changed it again....now, no leaks, but still this odd high low side pressure that has been plaguing the car since late 2019
Is the oil retained thru the vacuum? I added some the first time I refilled it yesterday, a little less than 2 OZ, because I could see leftover dye and did not wanna overfill it.
I refilled it again this morning, only adding 12 oz of R-134a, and no oil, and it was blowing cold.....the pictures below are the gauge while it was working this morning, the capacities from the FSM and the oil and oil injection tool I use
The compressors were pre-filled. And I think that there may have been nothing wrong, and could have been mis-diagnosed the 2nd time, but I had it changed anyway because it had a warranty.
Last edited by blackandwhite; 06-13-2021 at 03:23 PM.
#32
06-13-2021, 06:45 PM
Join Date: May 2017
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Coupe 6MT Premium RAS
Yeah PAG46 oil is the correct viscosity, you only need to add the full volume if you're replacing the compressor, if it's lost all it's refrigerant and you're recharging I typically add 2oz since that's about how much comes out from either a catastrophic rupture or a slow leak.
Sounds like it's probably not an oil issue.
I would definitely pressure test those lines next.
As for overheating when the AC turned on, the coolant system might not be holding enough pressure or the radiator might have blockage.
Sounds like it's probably not an oil issue.
I would definitely pressure test those lines next.
As for overheating when the AC turned on, the coolant system might not be holding enough pressure or the radiator might have blockage.
#33
06-15-2021, 02:02 AM
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Yeah PAG46 oil is the correct viscosity, you only need to add the full volume if you're replacing the compressor, if it's lost all it's refrigerant and you're recharging I typically add 2oz since that's about how much comes out from either a catastrophic rupture or a slow leak.
Sounds like it's probably not an oil issue.
I would definitely pressure test those lines next.
As for overheating when the AC turned on, the coolant system might not be holding enough pressure or the radiator might have blockage.
Sounds like it's probably not an oil issue.
I would definitely pressure test those lines next.
As for overheating when the AC turned on, the coolant system might not be holding enough pressure or the radiator might have blockage.
I took the car home and put the gauges on and I was getting about 130 on the high side and 30 to 40 on the low side but I didn't have much more refrigerant to add....it was equalizing at about 95, and building back to 130/40 when the compressor clicks back on.
I don't have time to check the lines until this weekend. But I'm going to evacuate it again in the morning and put the one can back in and see how it operates, And if my burping of the radiator does enough to keep the engine temperature down.
What does the compressor control valve do? Could it be causing my issue? I've read about it being a culprit for the high low side pressure.. How about the relay? What are its symptoms?
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