Had a service call last year for no cooling. Unit had a rheem 3t hp with a locked scroll compressor. Busy season, compressor under warranty and dirty O/D coil. Changed compressor, including installing high acid capacity filters,flared of course to make the 72 hour change out easier. Whole change out by the book, cleaned coil, etc. Came back three days later change filters, checked charge, everything fine and dandy.
Couple days ago, no cooling at same unit. Went and fond compressor out on thermal, and not coming back on.
This time did the entire system, and found a 2.5T, 11 SEER indoor coil, that some professional had cut the TXV off, and installed a piston on.
Told the owners that they were SOL, needed a new system, got the go ahead, ordered a trailer rated, yeah it's in a double wide, split system of the proper size;3T, and when it came in went to job and started the change out.
Had the O/D unit off and was starting on the A/H when my helper pointed out that the new system was too big by 2.5" to go back into the closet. At this point talked to the owners, who account for about 30% of my yearly gross, and explained the options.
Decided to go back with a compressor change out, but could not get the head to come up past 165psig, on a 85 deg day. Talked to a fellow who worked in the field for about thirty years before he started teaching and he told me that it was feeding hot gas from the O/D coil. Said try to get the head right and leave the suction to fend for itself.
Well charged it until it was feeding liquid back from evap, and head moved to a high of 175psig.
Reclaimed the excess and hooked in a low abient control to cycle head while in cooling and allow fan to run normal during heat mode.
But some little bug in the back of my head is telling me that heat mode may be the culprit.
As a note, this has become a self appointed mission of mine. Charged the owners for materials and at a low mark up. Nothing for labor. They have told me to put a heat pump package unit in when this fails, so right now it is a matter of me versus the machine demons.
Of course, my old boss told me to put the package unit in and go make some money, but obsession is a hard habit to break.