On Thu, 27 Nov 2008 00:30:54 -0500, Steve B. wrote:

I have a relative who just bought a home and is having problems with
her heat pump.

Equipment is Rheem
Outside Model RPMB-036JAZ
Inside Unit RCHJ-36A2AS21

In cool mode the unit seems to work fine.

In heat mode the compressor runs for about a minute and trips the over
pressure button. I don't have gauges but you can tell from the sound
the compressor is making that is working harder and harder until it
clicks out on over pressure.

Sounds to me like the outdoor checkvalve or metering device is
restricted. If that was the problem in this neck of the woods it's
going to cost close to $1000.00 to fix (recover refrigerant, sweat out
old fitting, install new fitting, install line drier, pull vacum to
500 microns, weigh in factory specified refrigerant charge) . Not
worth it if the system is over ten years old.