I was working on a water source heat pump Trane serial number# W04C11546 MN# GEVB02411J0110TL. The unit is an upflow with the compressor compartment being on the bottom and the fan and coil on top.
The problem is that the unit will run for about one minute in cooling mode then goes off on high head (400 psi r-22). Unit runs fine in heat. I replaced the txv to no avail. Believe the problem is the reversing valve at this time, but was wondering what else could possibly be the cause as I normally work on standard split systems and package units.
I am only working on this for my friend who has a loft in downtown LA. I run my business in the 'burbs, and water source heat pumps are rarely seen here.