A/C not cooling

Tiny
A1953
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Low pressure Schrader has definitely got a slow leak. Testing the HP Schaefer. I am going to try to pick up a tool for changing the Schrader valve stem without losing pressure in the system. Anything I should be aware of for that? At 25 PSI, has the system already been compromised and do I need to vacuum anyway? If there are other leaks they are so small that I can't see them. How beneficial (or detrimental) is the r154a with leak stop?
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Sunday, January 10th, 2021 AT 1:07 PM
Tiny
STEVE W.
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Don't use leak sealer unless you want to start changing other parts, it has a nasty habit of causing failures in valving and compressors. I would probably opt to pull a vacuum but it's not strictly needed.
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Sunday, January 10th, 2021 AT 3:08 PM
Tiny
A1953
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Thanks for the input. Had to go for a long drive today. Some of it in traffic and 80-85F in the sun. I had put a finger of a nitrile glove over the high and low p valves in case that was the problem. The A/C worked great all day! I plan to change the Schrader cores tomorrow and then pull a vacuum and then charge the system. I was under the impression that 200 PSI on the high side (45 on the low) was a target to shoot for with the compressor running and the car idling. Did I read that correctly?
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Sunday, January 10th, 2021 AT 8:36 PM
Tiny
STEVE W.
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Pressures all depend on the system and temperatures. For the temps you posted the pressures at idle look okay, It's possible that just the schrader leak is the issue, those can act strange at times and actually increase how much they leak as the pressure on the internal seal drops and the seal surfaces "relax".
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Monday, January 11th, 2021 AT 3:52 AM
Tiny
A1953
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Yes. Came out this morning and the glove was sucked down on the LP Schrader. Pressures were 20 and 25 so I imagine that I have a leak somewhere close as well. Changed the Schrader cores and the o-rings on the fittings on the firewall. (I was able to see a little better with the UV light as I started while it was still dark). It seemed like a possibility that they were leaking a little. Pulling a vacuum now and will recharge and let you know what I find. If this doesn't work, I think I will need a sniffer. Thanks for hanging in there with me!
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Monday, January 11th, 2021 AT 10:06 AM
Tiny
STEVE W.
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If it was drawn in it's leaking, but there is also a leak somewhere else if the numbers dropped like that.
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Monday, January 11th, 2021 AT 1:51 PM
Tiny
A1953
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Agreed. I don't have the car today, but am going to check the pressures when it gets back. I think that I will have to get ahold of a sniffer.
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Monday, January 11th, 2021 AT 2:57 PM
Tiny
A1953
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Well, that was not successful. The car was driven for one hour this morning. A/C worked okay. Coming back in the evening, A/C not working. I tested the A/C when the car got back. Engine still warm and idling testing 85LP and 85HP, 10LP and 100HP when I turn on the A/C. Clearly still losing refrigerant. I will see if I can get a sniffer and go from there. Thanks for your patient help.
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Monday, January 11th, 2021 AT 7:22 PM
Tiny
STEVE W.
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You will find it.
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Monday, January 11th, 2021 AT 10:18 PM
Tiny
A1953
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Hey Steve. Finally got some more time to work on this. Took the car to a mechanic and paid him to use his refrigerant sniffer to try to find the leak, but no joy. He suggested that I replace the out line from the compressor to the condenser as he often sees them go. Once that was replaced, A/C is nice and cold, but still has periods, while driving when A/C basically quits. I cannot hear the click but I am thinking the compressor must kick off. Layer on the same drive, the A/C will work again. I have been waiting to see if I still have a leak, but the pressure seems to be holding.
Do you think I might have a sensor issue?
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Wednesday, March 3rd, 2021 AT 12:29 PM
Tiny
STEVE W.
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It's possible because of the number of times it has leaked down. When it came back on after shutting down, did the air smell any different? Like the musty smell that you can get from ice melting? Was it humid at the time it shut off?
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Wednesday, March 3rd, 2021 AT 12:42 PM
Tiny
A1953
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It is humid. Not musty.
Thanks for your help!
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Wednesday, March 3rd, 2021 AT 3:31 PM
Tiny
STEVE W.
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Okay, humid could have made the core freeze up, the system will then shut down until the ice has a chance to melt away from the sensor. That could take a bit. About the only way to know for sure would be to connect up to the sensors and watch what they are doing.
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Wednesday, March 3rd, 2021 AT 5:25 PM
Tiny
A1953
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Right. Can I bypass that sensor to test if it is the problem?
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Wednesday, March 3rd, 2021 AT 9:08 PM
Tiny
A1953
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I can check to see if the evaporator is actually freezing?
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Wednesday, March 3rd, 2021 AT 9:10 PM
Tiny
STEVE W.
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The connector for the sensor is outside the case above the blower motor. With it unplugged you can test for the resistance using the table. If it isn't correct then it gets replaced. That could be tricky as the sensor is actually set on the evaporator core. The book tells you to remove the core to replace it but if you could reach in there through any opening and get to the core you might be able to just stick the new one in there and connect it up. I know of one person who reached in through the cabin filter opening.
To check if it's freezing up would involve seeing the intake side of the core.
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Wednesday, March 3rd, 2021 AT 9:58 PM
Tiny
A1953
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Thanks for the info. I will not have access for a few days, but will get back to you.
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Thursday, March 4th, 2021 AT 8:38 AM
Tiny
STEVE W.
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No problem. It's possible the pressure switch could be flakey as well but with those they usually fail and shut the system off.
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Thursday, March 4th, 2021 AT 9:56 AM
Tiny
A1953
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Good to know! Thanks again. Will let you know what I find.
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Thursday, March 4th, 2021 AT 8:22 PM
Tiny
A1953
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Hello again,

Steve, I gained access to the car again. Couldn't read the resistance charts when I magnified them, so I bypassed the thermistor.
A/C seems to work fine with thermistor bypass. So I guess I will just replace that. Do you have a good source and if we run the A/C without the thermistor to control, is intermittent use okay?

Thanks again.
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Monday, March 22nd, 2021 AT 11:20 AM

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