Fired up my 5 ton Carrier AC. Low side showed 50 PSI for a couple of hours then drops to 15-20 PSI. Assume freeze-up.

Defrost

Today I start adding R-22 (slowly). For the longest it never went above 55 PSI. After about an hour at 55 PSI it would jump to 75 PSI & slowly descend back to 50 PSI. Stopped adding R-22.

Shut unit off for about an hour. Restarted and low side shows 75 PSI. Slowly drops to about 65 PSI. VERY Confusing. Connect gauges to high side. Gage jumps to 300 Psi and SLOWLY climbs to 400 PSI. However low side barely changes. Indoor air around 75 Degrees.

That is where I am now. THANKS for any replies.

Sounds like non condensibles in system. Contact someone with a EPA certificate to perform work with R-22.

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Originally Posted by hvac1000

Sounds like non condensibles in system. Contact someone with a EPA certificate to perform work with R-22.

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How can that be? The system has been working fine for about 3 years with no problem. Where would it get non condensibles?
Thanks

Any thing can happen. Contact a professional to have your system serviced. It could be a valve but TXV's do not go bad very often. There are many other possibilities.
Dirty indoor coil.
Dirty filter.
Floater in system (Dirt). It can break loose any time.

Quote:

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Originally Posted by hvac1000

Sounds like non condensibles in system. Contact someone with a EPA certificate to perform work with R-22.

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Also could it be an overcharge combined with a bad TXV? It does have an inline filter in the High side which should trap floaters. I guess that it could also be clogged.
Thanks.

Anything is possible.

Quote:

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Originally Posted by hvac1000

anything is possible.

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Runtime Pressure Chart
Min:Seconds Low Side High Side
0:30 85 300
1:00 74 290
1:30 72 280
2:00 70 285
2:30 70 310
3:00 69 340
3:30 68 325
4:00 68 330
4:30 68 360
5:00 68 370
5:30 68 375
6:00 68 385

Got scared. Shut down unit
Sorry to be such a pain in the A, but there is only 1 AC serviceman within 30 miles (Rural Texas) & I know that he will take advantage of his mother or anyone else. If I have enough knowledge, maybe I can keep him halfway honest.

Sounds like the area need more qualified service persons. Good luck.