Need some A/C help - Page 2 - ZR-1 Net Registry Forums

jss06c6 · 08-09-2020

Hans, definitely sounds like you have a blockage somewhere. That system should equalize in the 90 - 95 psi range overnight. How did the screen look when you replaced it? Normal to have some debris, but should be trapped in the filter. It sounds like you've got some garbage in the system somewhere. Probably need to get another dryer after you flush the system too.. hopefully not trapped in the evaporator..

Clean it, get proper oil charge in it, pressure test and then nice long vacuum test. Watch overnight to make sure you don't lose more than 2-4 psi (temperature drop in desert!) And go for it again.

Sent from my SM-G950U using ZR-1 Net Registry mobile app

Ccmano · 08-09-2020

Quote:

Originally Posted by jss06c6

Hans, definitely sounds like you have a blockage somewhere. That system should equalize in the 90 - 95 psi range overnight. How did the screen look when you replaced it? Normal to have some debris, but should be trapped in the filter. It sounds like you've got some garbage in the system somewhere. Probably need to get another dryer after you flush the system too.. hopefully not trapped in the evaporator..

Clean it, get proper oil charge in it, pressure test and then nice long vacuum test. Watch overnight to make sure you don't lose more than 2-4 psi (temperature drop in desert!) And go for it again.

Sent from my SM-G950U using ZR-1 Net Registry mobile app

Steve, the old orifice tube that came out was surprisingly clean, just a small bit crud on it. Yes, looks like I'll have to pull it apart again. I'm hoping it's just the orifice tube. However it was doing the high heat thing before I changed the condenser. It will be next weekend before I can get to it.
H

Ccmano · 08-18-2020

Update, the car has been sitting for a week or more. I've been busy with other things. Went out today and hooked up the AC gages to the car. Car was not running ambient temp~90 degrees 30 percent humidity. Surprisingly the static pressures had equalized to ~100 psi which according to the manual is correct. I started the car and after warm up running at 2000 rpm Low side was ~27psi, high side ~290 psi, and the duct temp inside the car came down to ~43F. All of this is normal according to the manual. I turned off the car and for the first time the high and low sides started equalizing immediately, but slowly. Also normal. I didn't drive it, probably should have. Will do that tomorrow.

What continues to baffle me is that the compressor is not cycling Off and on, it just stays on. According to the manual it should (under the correct circumstances) cycle. Most importantly, and the reason I'm doing all this is that with the AC on the coolant temps rise unchecked if I drive in traffic or let it idle for an extended period. The car has a new aluminum 3 core radiator, new condenser, accumulator/drier and orifice tube. Both fans come on with the AC on.
That can mean only 2 things, either the condenser is dumping so much heat the cooling system can't keep up (which begs the question, why, compressor not cycling?) or the cooling system is some how compromised and can't handle the extra heat. Tho... with the AC off there are no cooling issues at any temperature and now with the new radiator it runs even cooler.

I've emptied and refilled the cooling system multiple times for various reasons but the car has always behaved this way. So I'm inclined to think an air bubble is not the issue. I suppose a thermostat that doesn't fully open is a possibility. However I'm still not convinced the AC system is operating correctly. Heck two weeks ago I would have thought the AC had a blockage.

Oh and stupid question to which I can't find an answer.... the orifice tube goes into the evaporator tube long side down, correct? That's the way the old one came out, but I have read that in older GM CCOT Systems it went in short side down.

Your input is encouraged.
H

08-09-2020	#11
jss06c6 Join Date: Aug 2015 Location: Magnolia, Texas Posts: 884	Re: Need some A/C help Hans, definitely sounds like you have a blockage somewhere. That system should equalize in the 90 - 95 psi range overnight. How did the screen look when you replaced it? Normal to have some debris, but should be trapped in the filter. It sounds like you've got some garbage in the system somewhere. Probably need to get another dryer after you flush the system too.. hopefully not trapped in the evaporator.. Clean it, get proper oil charge in it, pressure test and then nice long vacuum test. Watch overnight to make sure you don't lose more than 2-4 psi (temperature drop in desert!) And go for it again. Sent from my SM-G950U using ZR-1 Net Registry mobile app

08-18-2020	#13
Ccmano Join Date: Jun 2006 Location: Sparks, NV Posts: 2,852	Re: Need some A/C help Update, the car has been sitting for a week or more. I've been busy with other things. Went out today and hooked up the AC gages to the car. Car was not running ambient temp~90 degrees 30 percent humidity. Surprisingly the static pressures had equalized to ~100 psi which according to the manual is correct. I started the car and after warm up running at 2000 rpm Low side was ~27psi, high side ~290 psi, and the duct temp inside the car came down to ~43F. All of this is normal according to the manual. I turned off the car and for the first time the high and low sides started equalizing immediately, but slowly. Also normal. I didn't drive it, probably should have. Will do that tomorrow. What continues to baffle me is that the compressor is not cycling Off and on, it just stays on. According to the manual it should (under the correct circumstances) cycle. Most importantly, and the reason I'm doing all this is that with the AC on the coolant temps rise unchecked if I drive in traffic or let it idle for an extended period. The car has a new aluminum 3 core radiator, new condenser, accumulator/drier and orifice tube. Both fans come on with the AC on. That can mean only 2 things, either the condenser is dumping so much heat the cooling system can't keep up (which begs the question, why, compressor not cycling?) or the cooling system is some how compromised and can't handle the extra heat. Tho... with the AC off there are no cooling issues at any temperature and now with the new radiator it runs even cooler. I've emptied and refilled the cooling system multiple times for various reasons but the car has always behaved this way. So I'm inclined to think an air bubble is not the issue. I suppose a thermostat that doesn't fully open is a possibility. However I'm still not convinced the AC system is operating correctly. Heck two weeks ago I would have thought the AC had a blockage. Oh and stupid question to which I can't find an answer.... the orifice tube goes into the evaporator tube long side down, correct? That's the way the old one came out, but I have read that in older GM CCOT Systems it went in short side down. Your input is encouraged. H __________________ 90'ZR-1 #1461 Red/Black Ported Intake, Degreed Cams, OBX Headers & Exhaust, Fidanza FW, Secondary Delete, Custom tune, C6 GS Wheels. Sold 08 C6 Z51 Crystal Red Metallic Sold Vararam Intake, Tune, Sold 05 C6 Z51 Red/Black Sold 90'ZR-1 #1723 Black/Gray Sold but not forgotten 91' Z51 L98 White Vert. My First, you always remember your first. Sold. Last edited by Ccmano; 08-18-2020 at 09:04 PM.