Hello again
I have a question
I have a ducane 2 tons heat pump it work fine on cooling but when is switched to heat high discharge pressure goes to over 300 psig and suction pressure goes down to 0 psig and outdoor unit shut off, filter is clean, blower is fine unit runs for about 1 minute
Thank for any help I can get on this

Sounds like a restriction in the outside piston (metering device) If the head pressure went to 300 and the suction stayed aroung 50 or so I would say it is poor indoor airflow.

You might want to check out what you find by using the following link:

www.ducanehvac.com/res/pdfs/ac/20407501.pdf