Goodman heat pump not working

[carco21554]

Have a Goodman heat pump that is not working except on back-up electric heat. When heat pump is turned on the compressor kicks in and out every 5-9 seconds then finally runs for a few minutes continuously. After a while the compressor kicks on and off every 2-3 seconds. Meanwhile house temp has dropped 2 degrees in about an hour at ambient outside temp of 40-45 degrees. Can not get to work at all when less than 30 degrees. Been using the electric backup for a few days it works good. installed 2011, model ARUF,
Suggestions welcome Thank you. bob

[KDGrayson]

What temperatures is it outside when this happens?
Does it matter if it is below 40F or does it do this regardless of the outdoor temperature?
The 2 copper pipes to the outdoor section should be extremely hot in the heat mode, if they are not you may as well shut off the compressor as no heats being pumped into the home.
It sounds like you could be low on refrigerant or the heat pump reversing valve or compressor are tired, there is no way to tell for sure without some further assessment.