michael0584
1/2 ton status
I'll check to see if the pressure equals out.
CK5
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AC Diagnostic Help Needed
- Thread starter michael0584
- Start date
michael0584
1/2 ton status
I did pull a vacuum and let it sit a bit and it held at 30. Don't think there is a leak. I was just double checking with my leak checker.
michael0584
1/2 ton status
I did not flush the system. I inspected the compressor lines, dumped the old oil and it was all spotless. Pulled a screen out of the old compressor and no debris. Everything was perfectly clean. This compressor didn't blow chunks. In fact I'm fairly certain now there was nothing wrong with it since the issue has pretty much stayed the same.What the heck?
Did you flush the system while it was open? Just wondering if something is jammed in a line somewhere. Sweating only comes from cooling and cooling only comes from pressure + a restriction. If the old compressor blew chunks, that would explain the crappy pressures you had before and also why it's like a twilight zone A/C now. You always flush the evap, condensor and lines after a compressor pukes.
It kinda sounds like the system has contaminates/non-condensibles in the system!
How long was the vacuum pump on the system after exposure to the atmosphere?
A couple things I don't understand!
High side shouldn't sweat, it should be warm, or even hot, to touch!
You said you had to add refrigerant twice...that says leak!
Are the lines going to the rear coil in decent condition? I've had 2 Suburbans that developed leaks in fittings going to the rear!
When vacuuming down the system, can you get ahold of a micron gauge! Even though you hold 29 inches of vacuum, watching how fast your microns rise can tell you if there's a leak, or just contamination!
Residentially speaking, you could hold vacuum "all day" and still have problems because of contaminants! Moisture from the atmosphere that made its way into an open system can freeze during the refrigeration cycle and cause blockages that create hard to diagnose issues!
If you're absolutely sure there are no leaks, get a vacuum pump on it overnight! The hotter the surroundings, the better! That should give it enough time to boil off any contaminates! Then weigh in your charge and see what happens!
How long was the system open to the atmosphere during the compressor swap?
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michael0584
1/2 ton status
only a few hours.
michael0584
1/2 ton status
I've been on vacation for a week and just got back so the car has been sitting a 2 weeks (did not drive it the week before we went on vacation). Cranked it up to move it and left it running a bit and noticed ac was sweating. Checked and it was kinda cooling. 78 degrees out the vents and 90 outside (Nighttime). Since it was slightly cooling I hooked the gauges to it and it was about 20 low side and 110 high side. Added 1/4 a can of freon to attempt to get the pressure up and got it to 30 but no change in high side. Also not much change in high side when compressor cycles. Low side goes up but high side doesn't go down. It actually goes up about 5psi. No change in cooling after adding the freon either. I ordered front and rear expansion valves while I was gone. (Got both for about $20 total). I think this weekends goal will be to replace the expansion valves. I feel like there's something keeping the pressure down like the expansion valve stuck open? Oh and when I added freon I did not think it was low just wanted to make sure that's not what it was before I tore it down to replace the expansion valves.
I remember one time puzzling over weird pressures, then I discovered there was a problem with the high side tap not really engaging the Schrader. Not cooling is not cooling, but keep in mind that tools can lie to you.
michael0584
1/2 ton status
I just verified pressures with another gauge set and they are the same. Static pressures are low 91 high 95. Started engine up and ac on low 29 high 100. The high side pressure really doesn't change much.
Over charging too much will also lower your temp drop! Does driving the vehicle help drop your outlet temps? More air across the coil will help extract heat!
Also, keep in mind, every time you open the system to change parts, you are letting contaminates into system! It will need vacuuming and leak checking again!
Also, keep in mind, every time you open the system to change parts, you are letting contaminates into system! It will need vacuuming and leak checking again!
Is your high side sevice port between the compressor and condenser? If it is not the condenser could be restricted and you're not seeing it because of where the port is. If i remember correctly the drier is made to the condenser and they were bad for getting plugged up
michael0584
1/2 ton status
You may be on to something with the condensor/drier. The high side the service port is after the condensor not between compressor and condensor. I replaced both expansion valves and vacuumed the system and recharged with the correct amount of freon. 40 low side 120 high side. 93 degrees outside. Driving down the road best I could get from vents was 73 degrees.
Double check your high side port location. Obviously there is one where you are hooking your high side gauges up, but its fairly unusual for there not to be one before the drier and condenser. Your system may have two. I would be reluctant to try charging an unknown system without knowing the high side pressure before the drier.
I have seen too many hoses blown because someone just hooked up the low side to just "give it a quick shot" only to discover it was not low on freon, it had a stopped up drier. I have seen the ports in some unusual places before, but almost always before the drier.
Worst place was right after the compressor, about 3 inches from the housing. You had to either wait a while after turning off the car, or use heavy gloves to take the hose fitting off after it had been running a while.
Talk about hot!
I have seen too many hoses blown because someone just hooked up the low side to just "give it a quick shot" only to discover it was not low on freon, it had a stopped up drier. I have seen the ports in some unusual places before, but almost always before the drier.
Worst place was right after the compressor, about 3 inches from the housing. You had to either wait a while after turning off the car, or use heavy gloves to take the hose fitting off after it had been running a while.
Talk about hot!
michael0584
1/2 ton status
Just checked and there is not a high side port between the compressor and condensor/drier. I went ahead and ordered a condensor/drier. $63 on Amazon.
michael0584
1/2 ton status
Ding Ding Ding Ding. Replaced the condenser, recharged back with 2.5 cans of freon and it's blowing ice cold now. Low side is 27psi and high side is 195psi, 81 degrees outside. Looks like the condenser or drier was plugged and I wasn't seeing the high pressure because the only high side port is after the condensor. Thanks everyone for all the help!
Awesome, good to hear you got it fixed !
