A friend of mine has asked me to come look at his heat pump.

He says it runs in A/C mode but doesn't blow cool air. I am thinking he may not be noticing it as the ambient is already cool and he may not be "sensing" a low temperature difference.

He puts the unit into heat mode from a "no-call" position, into the call for heat and it won't run. He went outside observed the contactor not pulling in, so he manually closed it... it ran for a few moments then out.

At first I thought it may be the low pressure control, but if so it shouldn't let the contactor energize period. It may be low on charge but obviously not low enough to open the LPC. I haven't been out to the site so I am not sure of anything... just going on his word.

Any ideas?