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Re: Charge by weight or pressure? Seeing hi pressure with a lot LESS than recommended R134 oz

Posted: Sat Jul 07, 2018 11:27 am
by r-mm
It's been 65-95% humid in the mid to high 80's here, then it broke to 70's and 45% rh. When it did I found the low pressure switch cut out and the AC wouldn't run! I suppose this makes sense - I charged with far less weight that I predicted I would need and did so in hot/humid conditions. I added the remaining charge today.

A question about TXV systems: does one expect the compressor to cycle? When it was under-charged but run in very hot/humid conditions the compressor did NOT cycle. After adding refrigerant I found that the compressor DOES cycle.

Re: Charge by weight or pressure? Seeing hi pressure with a lot LESS than recommended R134 oz

Posted: Sat Jul 07, 2018 11:48 am
by bohica2xo
Fixed Displacement compressors with a TXV may cycle. If the heat load exceeds the capacity of the system the compressor stays running.

The only reason for the compressor to cycle off is to prevent ice formation on the evaporator. Around here at 115f & 7% RH I can let an evaporator get to 20f without much issue on short trips. Where you are it would be a block of ice with no airflow.