Ptac unit my amana unit just blows air , it is not cold, I dont know if its not the conpressor. It could be the thermistor.

It sounds like your PTAC (packaged terminal air conditioner) unit is malfunctioning. When the thermostat is set to heating mode, the PTAC should be blowing warm air, not cold air. There are a few possible causes for this issue:

1. The PTAC may be low on refrigerant. If the unit is low on refrigerant, it may not be able to properly heat the air.
2. The PTAC's reversing valve may be stuck in the cooling position. The reversing valve is responsible for switching the flow of refrigerant between heating and cooling mode. If it is stuck in the cooling position, the PTAC will blow cold air even when the thermostat is set to heating mode.
3. The PTAC's heating element may be malfunctioning. If the heating element is not functioning properly, the PTAC will not be able to heat the air.

I recommend contacting a trained HVAC technician to diagnose and fix the issue with your PTAC. They will be able to determine the cause of the problem and repair it properly.

How are you determining that one section.is cold and one warm? If this is in fact the case you have a blockage in the coil or a compressor that is down provided this is a multi compressor unit.

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!

bad switch, bad motor capacitor, bad motor.

If the unit is frozen you should be able to see ice at the indoor coil. If you pull the air filters and peer inside to the indoor coil there may be ice. Either way it needs service. If no ice and blowing cool not cold it could be the condenser coil is dirty. On the outside you can see the air leaving side of the condenser coil. The air entering side is the side that gets dirty and can only be seen by pulling the unit out of the wall. Its best to leave it in the wall and call a tech that has experience with ptacs.

check heater coil may be faulty may be a faulty thermostat or temp sensor

freon is low or outside is very cold

the board or the heater need to be replaced

Onl full service comes to mind.

Take the buttons off of your unit and remove the board cover by taking out the 2 screws on each side holding it in.  You will See on the right hand side of the board 4 post specifically , 2 for your indoor thermistor and 2 for your outdoor.  unplug your inddor  from the board ( make sure power is off)   and there should be a plate you can remove on the front of the unit on the right hand side of your evaporator coil , remove this and disconnect your thermistor from the coil (should snap right off )   pick up a new thermistor and just slide it right back in.