We have taken over the service at a local retirement center. About a year and a half ago another contractor installed about 80 1.5 ton heat pumps and they've been having a lot of problems.
We've had compressors and reversing valves go on a few of them. A few weeks ago a tech found one that no matter what the head pressure was about 500psi and blowing reliefs. Ordered a new txv and reversing valve. They cam in yesterday and a different tech went to install them. During charging, he was experiencing very crazy things. after about 14# of 410, he couldn't get any kind of suction or head pressure (normally these units take 8-12#).head pressure at 150, suction at 50.
Today he went out with our service manager, thinking there was a plug, or bad compressor, or something, they eventually found the cause.
The installing company mixed the liquid lines up with the unit next to it.