Heat pump fault

[Mattbilinski]

Hi guys

I'm new to the trade so I hope you can help.

I have a heat pump which works fine in cooling mode, but when I turn it over to heating it starts up fine and even heats for a few sec, then my suction pressure drops my suction line freezes up and sounds like liquid in the compressor!

I've check the rv which seems to be working fine, and I'm waiting for a access panel to be cut in the ceiling to access evap coil.

Unit is a apac. Will post further details if required.

[r.bartlett]

Are you certified to work on air conditioning ?