Model: Pickup C1500
Engine Size: 4.3
Refrigerant Type: R134
Ambient Temp: 80
Pressure Low: 10
Pressure High: 80
Country of Origin: United States
Initially, the AC was warm, so I hooked up the gauges and found no pressure at all. Decided to charge a little 134 to locate leak, but couldn't get any to go in the system. Vacuumed to get negative pressure to charge, but still no dice. Redid the connections several times, heated the 12 oz can and still very, very little refrigerant would go into the system. After many attempts I was only able to get a few ounces in there and found the leak. Could this be a problem with my gauge connections? I've got pressure readings, and I did try to charge the high side with the truck off and the low side while in vacuum. Any suggestions on making the charging process easier when the repairs are done?
Also, I noticed that the line coming out of the condenser was frosting up. Was that due to a low charge or is there another problem I should be looking for?
Could you make a recommendation for type of oil, weights of refrigerant and oil, and other information you think I may need? I plan to replace the leaking evaporator, accumulator, and o-tube. I am also contemplating replacing the compressor since I'll be in it that far and there is oil stains from behind the clutch although I was not able to detect anything there. Hope AMA can help me out again.
Thanks to all who make this a great site! Thanks AMA!
Your O tube is in the line coming out of the condenser, and it will be frosting "after" the tube. Due to low charge probably, but you should pull it out and check it..As far as refrigerant not going in, you have a bad connection somewhere. Try pressing down on the service port connections when pulling the vacuum or charging.. The vacuum alone should have pulled in almost a can(Suspect you just pulled a vacuum on the hoses...) .. But fix the leak, check the O tube, and let us know if you're flushing the rest of the system as that will determine how much PAG 150 oil you'll need. I'll post a link to capacity's after dinner, if no one does before that..Hope this helps..
refrigerant capacitys also was the compressor running when you got zero pressure readings? should not have been able to engage if it was empty....??
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Edited: Tue January 08, 2008 at 6:26 PM by Chick
For some reason, I had a hard time getting the refrigerant into the system. I first tried to dump liquid into the high side when not running. then heated the can while running to dump some in the low side. I jumpered the clutch to get the compressor going and got enough in there for it to short cycle without the jumper. But that was it. I did want to get the entire can in there so I could see if there was any cooling, but I took a very long time just getting half (6 ozs) in there. Knowing that the evap was leaking I just gave up. The rpms of the motor did cause pressure changes, so I am pretty sure that I was into the system.
I do plan to flush when the system is completely opened.
Thanks so much for your help!
I completed the job of repairing the AC on this 1995 Chevy p/u by replacing the evaporator, accumulator, compressor and o-tube. The system/cooling works great with much thanks to Jack, at AMA, for the suggstions and correct parts. However, I did notice that the direct replacement compressor was a little noisy. Is this normal? Prior to installation, I added 3ozs of oil, hand turning the compressor numerous times so I am sure that it is well lubricated. Will I have to worry about this getting worse in time or is it something that is normal with this type of compressor.
Also, any suggestions on where to get a gasket for the yellow hose on the side that attaches to the vacuum pump?
Thanks for all the help!
My gauge set does not push down the valve on the high side of my '94 Suburban, doesn't reach down far enough to open it. I have to hold it on hard to get a high pressure reading. And it was R134a, factory. Maybe yours is similar, not opening high side.
R4 compressors are historically a bit noisy....as Chick states...however, a major contributing factor to some of the noise issue is a lack of lubricant to the compressor. It was stated that 3 oz. was added to the compressor..this is great..however, the operation of the system without a complete recharge amount may also contribute to an increase in compressor noise due to the lack of lubricant flow into the compressor. It is essential that the system be fully charged to maintain proper lubricant flow to the compressor during system operation. One of the downsides of retro fitting is the undercharging of a system to facilitate pressure/temperature ranges that are deemed acceptable...this undercharge condition may result in increased noise issues or a total failure of the compressor. Keep in mind that there are no true operational pressures guidelines for a retro fitted system...there are 'guess-ta-mations concerning operational pressures... the best method to insure complete system recharge is the use of calibrated recharge equipment to monitor the exact amount of refrigerant within the system (a percentage of total R12 specs) and temperature drops to determine correct recharge amounts.
Good luck with your repair!!!
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Ice, thanks! The system was originally R134 and was charged (although using 12 oz. cans) to the 32 ozs as called for. The noise is bearable, I was just concerned that it may lead to premature compressor failure. The noise started as soon as the clutch engaged, so there was at least 3 ozs of circulated oil in there at the time.
Very good point about low refrigerant not circulating enough oil causing compressor problems. Again, a great learning experience here. Thanks to all for your great advice!
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