-
Recently Browsing 0 members
- No registered users viewing this page.
-
Forum Statistics
250.3k
Total Topics2.7m
Total Posts -
Member Statistics
342,740
Total Members8,960
Most Online
-
Who's Online 9 Members, 0 Anonymous, 1,285 Guests (See full list)
-
Latest Articles
-
Posts
-
I was using recirc/max air. Especially if it really hot i start out by lowering the front windows a little with regular ac the go to recirculation after a few and rolling windows up. And it does not have the newest refrigerant. It has per the info under the hood r134. Not the new r1234yf. -
tldr; Shade tree mechanic stumped by variable displacement AC compressor. Not Silverado related, but for my 2000 Camaro SS. I've never really used the AC since acquiring the car a good handful of years ago. I plan to take it on a trip this summer so I wanted to make sure the AC was in good shape. On an 73 degree day in the shop with the car idling I set the AC on "Max", temp set to cold, and fan on hi. The compressor turned on and air turned nice and cold. I let it run for several minutes but noticed the compressor never cycled off. The engine was up to temperature enough that it began cycling the cooling fans on high. I had a set of manifold gauges hooked up and it was consistently at about 25 psi on the low side and between 200 and 225 psi (warm engine) on the high side. Per temperature charts, the low side is low (should be 30-35) and the high side is a little high (up to 170 per chart). I read the low pressure as potentially being under-charged underscored by a continually running compressor This was also underscored by temp readings of mid-20 degrees at the vents. Not just cold, freezing cold. Switching off the AC but leaving the HVAC fan on high produced a deluge of condensation underneath the vehicle. I was getting ice buildup on the evap core most likely. The low reading (25psi) concerned me that the compressor wasn't switching off so I swapped out the pressure switch. No change in behavior, still ran constantly. The AC clutch works fine as it engages/disengages with the HVAC switch on command. The compressor relay is good as I swapped it with two different known good relays just to be sure. Having eliminated that, and the pressure switch, I added refrigerant, thinking the constant run and low "low" pressure were signs of a slight undercharge. Makes sense, the car is 26 years old and it doesn't appear the AC system has ever been touched. Adding some R134a didn't meaningfully change the low side pressure. And that's when a lightbulb flashed upstairs. While I consider the car "old", it's possibly "new" enough to have a variable displacement compressor. Did some reading and sure enough. Dangit. I don't work on these for this reason. Adding refrigerant means the compressor will just compensate and won't really change pressures until it's severely overcharged or undercharged. But at least I wasn't getting ice/frost anymore, but instead high 30 degree temps out of the vents. That's more normal, but with variable displacement now I have no idea where my charge level is at. It's probably overcharged now. The high side even with the engine radiating serious heat was never really over about 225. The static pressure at room temperature is dead on, before and after the charge. Both high/low equalize after some rest. I'm thinking I'll need to take it to a shop. I want the proper charge level so I'm not working the compressor too hard. The only way to get an accurate charge is to evacuate and then re-charge with the exact amount specified for the system -- at least that's what I'm reading. Anyone here with modern automotive AC knowledge? -
Mine is in the shop for the AC now. While it did get cold after a bit, it would take a while to even start to cool the air at all. Turns out the compressor was bad and cycling. -
I call B.S. when I first moved to Texas my first house would only cool to 80 with the Texas heat. The AC tech said it was normal at 100 degrees outside. I remodeled the house put in a new AC. I could hang meat. My cars may need recirculating to start. Once moving it switches to regular AC and I could hang meat. Living in Texas no one would put up with only 20 degrees difference. -
By Silverado4x4 · Posted
AC in home or auto only cool down 15-25 degrees from outside temp, but what will help is to put the ac in recirc mode this will recirc the Inside cabin air rather then trying to cool down the outside hot air, I always have mine in recirc mode.
-
-
GM-Trucks.com Clubs
-
Black Truck Club
Open Club · 612 members
-
White Truck Club
Open Club · 380 members
-
Canadian Owners Club
Open Club · 282 members
-
Red Truck Club
Open Club · 156 members
-
diesel 3.0
Open Club · 279 members
-
Texas Owner's Group
Open Club · 371 members
-
NorthSky Blue Club
Open Club · 118 members
-
Midwest Owner's Group
Open Club · 212 members
-
2015 Custom Sport Club
Open Club · 5 members
-
GM Snow Plowing Club HD
Closed Club · 14 members
-
-
Popular Contributors
-
.thumb.JPG.2c573de60d3a3a4407c7d92298db46dd.JPG)
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now