Fan mode works, but when switched to cool, nothing happens etc...

SOURCE: PROBLEM WITH DOMETIC RV ROOFTOP AIR conditioner

Check at the compressor terminals between the Red and the terminal for the overload protector to see if you are getting power to the compressor on startup.

SOURCE: How to put refrigerant in Demotic RV Rooftop Air Conditioner

You will need to add a self tapping port to the suction side of the unit. You will have to determine what the size of the pipe is and then go to a local a/c supply company and buy one. It's kind of like a self tapping supply for water but for high pressure. Hope this helps. I would also put one in on the high side as well so you don't blow the valve in the compressor if you over charge it or the system is dirty.

SOURCE: We have a Coleman 7300 rooftop ac unit. When the

The fan motor is getting hot and going off on the internal overload in the motor.
This is caused by either a low voltage, a bad capacitor, or tight or dry bearings in the motor.
To check the bearings turn the power off to the unit, then spin the fan blade if it spins freely then the bearings are ok.
To check the capacitor you will need some kind of
tester or you can buy a capacitor and replace it, that's what a lot of people do. They usually don't cost very much.
To check the voltage you will need a voltmeter and measure the volts at the unit.

SOURCE: coleman 7300 rooftop air conditionor wont operate

When they sit allot - sometimes the fan will stick.. Take the cover off,, turn it on and see if the fan is stuck.. Spin it by hand to free it up..

SOURCE: odor when air conditioner turned on

Hi, If its a smell other then electrical burning, I would say it is coming from the evaporator coil inside. Take out the filter and clean it if it is the washable type and try and clean the coil. They make coil cleaner you may be able to get at your RV dealer to do this. This is the only thing I can think of that would have any odor. Unless there is something outside it is drawing in. The system is sealed and would not emit any odors other then a hot motor. You can check up top by removing cover to check the motors and to see if any critters have crawled inside. Let me no, keep me posed on what you find and if you need more help.
Sincerely,
Shastalaker7
PS Check the indoor blower motor also, it may be getting hot and ready to fail.