I encountered a RTU today that puzzled me. I can diagnose most issues with a refrigerant circuit but this one got me.
So here is the jist
Carrier rooftop unit in a strip mall, above a vacant store. One unit for the whole store. Property owner goes to show the store to a perspective leaser, calls in the no cool after unit runs for 3 days and still off temp
R-22 unit, 77 DB indoors 97 DB ambient
Suction pressure 80 psig, Head pressure 440 psig. So obviously the head pressure immediately set off alarms in my head. Super heat in the teens (I cant remember the exact number) subcool in the singles. So I cleaned the coil and got the badly hail damaged fins in decent order and fire it back up. No change. So I start thinking over charge as the target superheat according to the charging chart is higher than actual so I pulled some refrigerant off of it. Get the head to 400, but now my super heat has skyrocketed.
So I have hit a blank here and I am hoping someone might point me in the right direction for my trip back tomorrow. Sorry for the vagueness but I have seen way to many numbers today