Tempstar Heat Pump not running but Air handler is

[lgmccoy1]

My tempstar smart comfort 2000 heat pump has quit working. My air handler and thermostat are working on Auxillary Heat but the heat pump itself outside isn't running at all. I can't even hear humming and fan isn't turning on or anything. There is a circuit breaker outside my house mounted near the heat pump and it was tripped when I went to check it. I flipped it back on but heat pump will still not run. What could this be? After researching the net I've come up with three things, starting capacitor, fan motor, and high pressure cutoff. What do you think? What should I check first? There is also a pullout type fuse mounted on wall beside heat pump. How do I check this? Thanks in advance

Tempstar Smart Comfort 2000

[jumptrout51]

Remove the service panel cover from the heat pump.
Use your meter to check for 220 volts incoming power to the contactor.(No power check breakers/fuses).
Look at the capacitor,is it bulged on top?(bad).
With refrigerant gauges check for system pressure.(Approximately 120 lbs while idle).
With meter check for 24 volts at common (C) and R on the defrost board thermostat connections.
With T-stat set for heat check common and Y for 24 volts at the defrost board..

[JWWebster]

The pull out simply kills the power to the unit. Yank that out before doing any checks.

[niobrara]

Jumptrout,great break down.

[jumptrout51]

lgmccoy1 sent me a PM. He is out of refrigerant causing the low pressure sensor to stop 24 volts from going to the contactor.