Air comp. blows fuses

The cold that you describe may be just unconditioned air? If you are certain you can hear the comp operating for a couple of minutes, and then the heat starts, I would guess it is a reversing valve issue if it's a heat pump and it probably is. Or the control board acting up. I've had a lot of issues with the boards in the Amanda PTAC units. I can't remember how to configure it, but if you Google "Amanda ptac configuration", there is a lot of info online. May try a reset method first. Hope this helps!

Compressor is low on gas .

Do the tests in this post

http://ricksfreeautorepairadvice.com/heat-load-test-thermostatic-expansion-valve-system/

If the compressor has a start capacitor, replace it. If it does not, the compressor is at fault and needs replacing.

do you have an automatic change over thermostat? this would switch it from heating to cooling.

One amateur test is to place your hand on the compressor and see if it
is too hot to hold your hand on it. You may have a restricted condenser coil
If it is too hot then the condenser coil is restricted inside the unit
if not be sure and clean condenser coils with good coil cleaner.
You can put a fan on the compressor and see if it runs for another test to confirm it
If this was helpful please rate me.

Leo Ponder Appliance-Tyler,Texas
[email protected]

Could it be overheating, and automatically shutting-down, to avoid damage?
Shut it down.
Disconnect the AC power.
Remove the battery.
Purchase a can of compressed air, and give your computer a "blow-job", shooting compressed air into every orifice, to remove all the dust that could be acting like a layer of "insulation", preventing your computer from cooling itself.

First check you fuses you should have at least two fuses,2nd if that dont work take a wire and run it straight from the battery to the ac switch if it starts to blow the electric part of the switch has gone bad.If that don't work you might hjave a bad ac unit.

check the start gear for the comp.