I've got a York Heat pump that is not generating any heat. A/C mode works well, but starting late last winter (spring 2009), I started just using the emergency heat (its nat gas and I'm in TX so its realatively inexpensive). I'm wanting to try and diagnose the problem before I have a tech take a look at. Note that when I try to operate in heat pump mode, the indoor fan comes on as does the fan on the outdoor unit. I've left the unit on in heat mode for up to 1 hour and it did not heat up the house by one degree (have done this a couple of time in temps from 30 degrees to 45-50 degrees).

Does the vapor line (large, insulated) become warm/hot after the unit has run a while (5-10 minutes, check exposed section near O/D unit)? If not, but the system performs well in cooling, I would suspect a problem with the reversing valve or the outdoor metering device. System operating pressures in heating mode will reveal much of the mystery.

Thanks KC13. I'll check this out tonight.