Troubleshooting AC leak before charging with R134a

[1991 Corvette ZR-1]

Originally Posted by -=Jeff=-

when you guys are posting outlet temps of your AC, what is the Ambient Temperature? I found, the blower on mine gets good voltage, air velocity out the vents equlas that of my 2016 Charger, but the volume it not there. It will get the car cool on a hot day and the coolant temp hangs around 200-210 depending on type of driving ( traffic or moving)

Ambient temp out was 90 or 91 when I went for the test drive. Vehicle was in the garage and the thermometer read 89 sitting in the vent before turning on the AC. I used the vent right about the center console.

Originally Posted by HAWAIIZR-1

Thanks for sharing all your trial and tribulations. I found my AC was not cold and the compressor not engaging due to low pressure, but no codes. I charged with 1 can and bingo it works. But after I took off the line the low pressure Schrader valve is leaking. I fiddled farted with it trying to stop the leak, but I don?t have as new valve or the tool to change it. So I?m waiting on the valve core tool and the tool to replace the valve if needed without freon discharge. When it comes to AC I?m totally clueless, but I?ll learn with posts like these and YouTube.


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Haha well you will certainly get it done faster than I did! I believe the special tool that prevents discharge works very well. I used a generic removal tool due to the system being flat.

Anyone know what the rpm limit is for the compressor engaged? The highest I have had the engine up to was 4K.

[HAWAIIZR-1]

Ha ha. Well, the fat lady hasn?t sang yet. I saw a YouTube video about changing the valve core but the guy used the remover and found it was just loose. I will find out in a few hours when my order arrives.

Hopefully it goes smoothly. I still have to add more Freon, but in my case it seems it was just a slow leak from the Schrader valve core on the low pressure side.

Image1653165983.717922.jpgImage1653165993.637896.jpg


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[HAWAIIZR-1]

Update. I was fortunate that mine only needed a new valve core on the low pressure side. I added one more can of Freon and both static pressure and while running is perfect and cold.


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[mlipmd]

I would love to be able to use that tool and tighten up or remove my low pressure valve, but the way my accumulator tank and the fill tap is oriented, I can barely get the hose attachment from the can on there. The fill port is aimed at a 45 degree angle back to the right side and there is barely 2" of space in there. It looks like maybe there was an adapter added on to the accumulator fill port coming out near the top of the tank, maybe to convert my '90 car to R134?
Sorry the images are rotated 90* counterclockwise by the forum and I can't seem to fix that.

[HAWAIIZR-1]

Originally Posted by mlipmd

I would love to be able to use that tool and tighten up or remove my low pressure valve, but the way my accumulator tank and the fill tap is oriented, I can barely get the hose attachment from the can on there. The fill port is aimed at a 45 degree angle back to the right side and there is barely 2" of space in there. It looks like maybe there was an adapter added on to the accumulator fill port coming out near the top of the tank, maybe to convert my '90 car to R134?
Sorry the images are rotated 90* counterclockwise by the forum and I can't seem to fix that.

Why do you have to deal with the accumulator and the schrader valve on there? Sorry, I'm clueless on AC so asking. I my low pressure schrader valve that had a slow lead was up by the coolant recovery tank. I connected the manifold gauge set to the low pressure (upper/fatter pipe) and the high pressure to the lower/skinny pipe). Then again, mine was simply just low freon because of the valve core leak and glad my was a simple task. I will buy a pump to pull vacuum in the future as needed. Best wishes.

[mlipmd]

Sorry, I don't know what year you have but the low pressure port on my '90 is located on the side of the accumulator tank where a retrofit adapter was added for the 134a refrigerant. The high pressure port is on the middle of the high pressure line. There is no port on any line near the coolant recovery tank.

[1991 Corvette ZR-1]

Originally Posted by mlipmd

I would love to be able to use that tool and tighten up or remove my low pressure valve, but the way my accumulator tank and the fill tap is oriented, I can barely get the hose attachment from the can on there. The fill port is aimed at a 45 degree angle back to the right side and there is barely 2" of space in there. It looks like maybe there was an adapter added on to the accumulator fill port coming out near the top of the tank, maybe to convert my '90 car to R134?
Sorry the images are rotated 90* counterclockwise by the forum and I can't seem to fix that.

Yes, that is a R134A adapter that has been threaded on. If you were attempting to change the valve, that portion would need to be taken off before gaining access. Even then, as you said, clearance is an issue. You may get some extra space by removing the bracket which holds the accumulator in place to gently tilt it for more space to operate but the hoses are pretty stiff.

This is going to be an opinion some may not want to read, but due to the age of these components, the time may come when rebuilding most of or the entire system is necessary. My AC compressor leaked, all of the schrader valves leaked and my condenser was toast and rotting. Opening up the system meant I needed a new accumulator.

To get to the accumulator, you have to remove the compressor hose and low pressure hose. It is not going to happen. It is on there and the age of the parts does not help. There is a provision on the accumulator for a backup wrench while you attempt to remove the compressor hose. It will not hold as it is soft aluminum, you just round off the edges as the wrench slips around it. I had to hacksaw the connection off the accumulator still threaded into the compressor hose.

I then used my wrench on the compressor connection as the back up while I hit the other side with an impact wrench. It took a lot of force to break it free. Way more than you will be able to do leaning over the engine bay with each hand holding a wrench. The threads inside the compressor fitting were gone, completely wiped. The whole hose set was useless.

The passenger side of the accumulator actually broke free but took a lot of muscle and did not wipe the threads on the low pressure hose. That is good because had I needed to replace the low pressure hose, the connection that mates to the evaporator was SOLID. Same scenario there, not coming off unless it is cut off. Then you need a new condenser and you are draining coolant and tearing apart the car to get to that piece.

I guess what I am trying to say is this project is not for everyone. If you are going to dive in, pick up every single part outside of a new compressor before you jump in because it is a domino effect on parts if one is faulty or fights you to come off the car. I did it because I wanted to learn more about this specific system and I also do not trust any shops to do it right.

[mlipmd]

Since I now again have a major leak from my system (lost (2) 12 oz. cans of refrigerant in 48 hrs.) after filling it up, and since it could be the compressor that is leaking, and to replace that, if so, requires the plenum to come off, or it could be any of the other major parts, or even an O ring, I don't feel like tracking this down when there are experts who can do this. And none of those old parts are going to be able to move easily, and I don't have the equipment needed to evacuate and flush and adequately refill the system, in addition to tracking down the parts. So sometime next week I will take a drive and bring the car back to South Georgia Corvettes and have Aaron Scott and his AC associate down the street look at it and repair/replace what's necessary. Then again I'll be set for the hot summer down here to come. Sometimes you have to refer the job to the experts.

[HAWAIIZR-1]

Originally Posted by mlipmd

Sorry, I don't know what year you have but the low pressure port on my '90 is located on the side of the accumulator tank where a retrofit adapter was added for the 134a refrigerant. The high pressure port is on the middle of the high pressure line. There is no port on any line near the coolant recovery tank.

Got it. I have a 95. Thanks.


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[Corvette95]

Originally Posted by HAWAIIZR-1

Ha ha. Well, the fat lady hasn?t sang yet. I saw a YouTube video about changing the valve core but the guy used the remover and found it was just loose. I will find out in a few hours when my order arrives.

Hopefully it goes smoothly. I still have to add more Freon, but in my case it seems it was just a slow leak from the Schaefer valve on the low pressure side.

Attachment 17733Attachment 17734


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I saw this post last week and was going to reply a tire valve core remover will work on the a/c schrader valve but then I saw where you said you were waiting on a tool so you didn't have to remove the freon... I have never seen this, will this this go onto either the high or low port and allow you to change the schrader valve core without evacing the freon or am I misunderstanding entirely. I would like to get a set if that is how they work. I still have original r12 and r134a in both of mine and believe my low pressure valve has a super slow leak (134a). It takes about a half a pound every two years or so ( I know, worse problems to have) but more info would be appreciated!