The system is a Marine
Air 16K BTU split system with a 12K air handler and a 4K air handler. The compressor sounds normal when starting/running, but on occasion I have noted a sound that reminds me of a pressure valve releasing when shutting the system down. It's not all of the time and I don't remember if it's when in heating or cooling mode.
When I run the test where I vacuum down the lines to/from the air handlers, I wait for several minutes and see no change on the side opposite of what I open up. I would expect to see something within that time frame. Is that not a valid assumption?
Since I see 115 PSI develop at the LP service
valve when in heating mode, I believe that the compressor is working properly and that the reversing valve is functioning properly.
To me this feels like a blockage between the reversing valve and the HP service
valve, which includes the condenser. This would explain why I see no pressure change at the HP valve when in either cooling or heating mode. However, I don't understand how that would occur. Likewise, whatever blocked the RV valve also effected the air handlers.
Am I just barking up the wrong tree or what?