jonb
09-08-2012, 10:05 AM
I have an A/C unit on the site I work on that keeps tripping on LP. Initially thought it could be a refrigerant leak so evacuated the refrigerant which weighed in at the correct system charge. I carried out a pressure drop test which was OK and then vacuumed down the system. I recharged by weighing in the refrigerant to the correct system charge.
When I run the unit the suction pressure drops very quickly and the unit trips on LP. The LP pressure then doesn't raise again for several hours.
I have checked the temperatures either side of the filter/drier and that seems OK. I am thinking its a faulty TXV but as I work on a gas site and getting an open flame permit is quite difficult I am hoping someone has another diagnosis. I tested the TXV with hot water but still no inrease in pressure until I adjusted the screw to fully out and then a got a small rush of refrigerant and a small increase in pressure. All coils are clean. Please help
When I run the unit the suction pressure drops very quickly and the unit trips on LP. The LP pressure then doesn't raise again for several hours.
I have checked the temperatures either side of the filter/drier and that seems OK. I am thinking its a faulty TXV but as I work on a gas site and getting an open flame permit is quite difficult I am hoping someone has another diagnosis. I tested the TXV with hot water but still no inrease in pressure until I adjusted the screw to fully out and then a got a small rush of refrigerant and a small increase in pressure. All coils are clean. Please help