Full charge after only half the freon?
Posted: Tue Sep 01, 2020 5:12 am
Howdy,
Kind of confused at the results after helping out a friend with his suburban. Basically the high/low pressures seem to be right on, but only after adding about half of the freon capacity.
Just a little background, I'm just an enthusiast with a private shop, I've fixed or replaced several AC systems in my own cars, everything has always seemed to go as expected.
I have a friend with a 1988 suburban with a 6.5 l diesel swap, he took it to a shop to have the AC charged, apparently they screwed around with it for a little bit, then they basically refused to work on it anymore, so he asked me for help. About a month ago I had just finished installing a factory AC system on my 1984 m1009 (K5 Blazer). So I was fairly fresh on the procedure..
The The suburban is basically a bastard, the compressor was installed about a year ago, but never hooked up. It was a ACDelco HT6 compressor.
After the shop looked at it, we replaced the condenser evaporator, accumulator with aftermarket parts from RockAuto for a 1988 vehicle, and the rear AC is a 'vintage air' aftermarket kit..
The first time he brought the truck over, he claimed the shop had put oil in it, so I pulled a vacuum on it, and began to charge it. I knew my K5 Blazer was perfect after 3.5 cans of 134a, so I just began filling his system.
Near the end of the 3rd can, I looked at the gauges and the low side was about 55, and the high side about 250. Outside air temperature about 85. My 134 a chart said it should be 40 to 50, and 175 to 210. Something wasn't right. I decided to just stop, and go search the forums for some answers. And try again a different day.
Apparently he used the AC on the next few days and then he told me the AC clutch had quit.
So go out there and inspect it, and the AC compressor is seized. Great.
We throw a bunch of new parts at it, I completely disassemble all the components and flush it all. We install a new four seasons HT6 compressor.
This time I add the exact amount of oil in.
I pulled a vacuum for 30 minutes... all good, so I charged it.
according to the service manual, it should take 54 oz of r12. I've always found that that translates to about 20% less r134.
I estimate we put in approximately 30oz, and the pressures are now 45, and 185. At 80 degrees outside
System seems to be running normal, and cooling pretty well. I am fearful of adding more.
I guess I'm looking for opinions on why it's only taking 30 oz?
I guess I'm still baffled, however I think I'm going to chalk it up to just a unique system. All of his lines under the hood are custom, a mix of parts from different years and aftermarket systems who knows.
As for why the previous compressor failed, I'm not sure how the compressor was cared for for the last year, or if it was ever exposed to the elements. He indicated to me that the shop "thought they overfilled the oil", but they didn't want to charge it cuz they thought "there might be a clog" etc etc I really know idea.
Basically, I hate working on other people's cars lol.
Kind of confused at the results after helping out a friend with his suburban. Basically the high/low pressures seem to be right on, but only after adding about half of the freon capacity.
Just a little background, I'm just an enthusiast with a private shop, I've fixed or replaced several AC systems in my own cars, everything has always seemed to go as expected.
I have a friend with a 1988 suburban with a 6.5 l diesel swap, he took it to a shop to have the AC charged, apparently they screwed around with it for a little bit, then they basically refused to work on it anymore, so he asked me for help. About a month ago I had just finished installing a factory AC system on my 1984 m1009 (K5 Blazer). So I was fairly fresh on the procedure..
The The suburban is basically a bastard, the compressor was installed about a year ago, but never hooked up. It was a ACDelco HT6 compressor.
After the shop looked at it, we replaced the condenser evaporator, accumulator with aftermarket parts from RockAuto for a 1988 vehicle, and the rear AC is a 'vintage air' aftermarket kit..
The first time he brought the truck over, he claimed the shop had put oil in it, so I pulled a vacuum on it, and began to charge it. I knew my K5 Blazer was perfect after 3.5 cans of 134a, so I just began filling his system.
Near the end of the 3rd can, I looked at the gauges and the low side was about 55, and the high side about 250. Outside air temperature about 85. My 134 a chart said it should be 40 to 50, and 175 to 210. Something wasn't right. I decided to just stop, and go search the forums for some answers. And try again a different day.
Apparently he used the AC on the next few days and then he told me the AC clutch had quit.
So go out there and inspect it, and the AC compressor is seized. Great.
We throw a bunch of new parts at it, I completely disassemble all the components and flush it all. We install a new four seasons HT6 compressor.
This time I add the exact amount of oil in.
I pulled a vacuum for 30 minutes... all good, so I charged it.
according to the service manual, it should take 54 oz of r12. I've always found that that translates to about 20% less r134.
I estimate we put in approximately 30oz, and the pressures are now 45, and 185. At 80 degrees outside
System seems to be running normal, and cooling pretty well. I am fearful of adding more.
I guess I'm looking for opinions on why it's only taking 30 oz?
I guess I'm still baffled, however I think I'm going to chalk it up to just a unique system. All of his lines under the hood are custom, a mix of parts from different years and aftermarket systems who knows.
As for why the previous compressor failed, I'm not sure how the compressor was cared for for the last year, or if it was ever exposed to the elements. He indicated to me that the shop "thought they overfilled the oil", but they didn't want to charge it cuz they thought "there might be a clog" etc etc I really know idea.
Basically, I hate working on other people's cars lol.