AC Learn and fix

[R422b]

Also most leak detection dye is not approved by compressor manufacturers and eaven if they do allow it they would prefer that you don't use it.

Soap bubbles and an electronic detector is the best way to find a leak.
The best soap bubbles solution I have found is big blue.
https://www.refrigtech.com/big-blu/

Only 2 things belong in a refrigerant circuit. Refrigerant and oil.

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[Eveready]

If you have access to nitrogen or co2 (not compressed air) then do a pressure check first.
The most pressure differential you can get with vaccum is less than 14.7psi and it is in the opposite direction that the refrigerant will be trying to get out so if there is some crud on the leaking spot it could Get sucked into the leak and male it appear to hold but then still leak under pressure.
The main purpose of pulling a vacuum is to remove moisture.

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I don't have access to nitrogen or C02 so I will just add a little refrigerant and see if it holds. I really do suspect that cap. I also have new schrader valves that I will put in since it is empty. Since it has not been all that long since it worked my hope is that there couldn't be much crud in it. If I can't make it work, I'm not out much and will take it to a good repair outfit . Either way I will have AC when it gets hot around here. I once spent a ton of bucks on the crappiest square body you ever saw but that junker had working AC when I sold it!

 

[delta_p]

I found one of the most problematic areas I had on my 96 c1500 ac system over the 20 something years was the little rubber ball check in the high side fitting. It seemed like it would always develop a leak there over time and they were always good new but when depressed again time for a re-seat attempt they just leaked worse. I finally ended up putting a schrader valve version in last year and so far so good. I also figured out to just barely crack it open with the service valve when filling etc. rather than wide opening the service valve. Seemed like it was less stressful on the fitting ball.

 

[Eveready]

I had another round with it today. I decided to put enough charge on it to activate the compressor. I hooked everything up and sure enough, the compressor started cycling but a reading of 0 that's ZERO on the high side. Low side built up to a reasonable pressure but high side would never get off zero and the compressor kept short cycling. Needless to say I didn't leave it hooked up very long. I think I will just bite the bullet on this one and take it in for service. Once it is working reliably I think I can keep it going OK .

 

[PlayingWithTBI]

I hooked everything up and sure enough, the compressor started cycling but a reading of 0 that's ZERO on the high side. Low side built up to a reasonable pressure but high side would never get off zero and the compressor kept short cycling

Odds are your high side connection isn't opening the schrader valve. If this is a conversion (from r12 to 134r) kit, look at the quick connect adapter and see if there's and intermediate plunger that will open the original schrader valve when you screw in the plunger. The reason it's short cycling is probably because you don't have enough Freon in the system yet. Is your low side gauge going lower than 20PSI just before it shuts off?

 

[Eveready]

It did go down pretty far. I will add some more refrigerant tomorrow. That lack of pressure on the high side sort of unnerved me. Most likely you are right about the schrader not contacting properly. I was a little worried about it blowing up!

Also I have a birdie in the Alternator so it will need to be changed. Will likely round one up tomorrow. Anything special I need to get in that regard?

 

[Eveready]

Lately I've only had time to start it and turn the AC on. Thus far the compressor is still cycling rapidly as I haven't put any more refrigerant in it. It does appear to be holding which makes me think that cap was the culprit. I think I will put more in it and see if it can be convinced to work.

 

[Eveready]

Another update. I got most of a can of refrigerant into it today and the compressor is still short cycling. I think I will chicken out and take it in for a diagnosis. One way or another it will be cool in this truck by the time Summer really warms up. Once it is working I think I can keep it going.

 

[R422b]

What were the pressures it was cycling at?

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[Eveready]

It would get up to about 50 on the low side and drop to 30 or so when the compressor came on. I cannot measure the high side as it appears that the schrader in the conversion kit is not releasing. I think I am going to take it to my favorite mech and throw money at it.