We have a Coleman 7300 rooftop ac unit. When the ac is switched on the compressor and fan both start working. After a few minutes the fan stops but compressor continues to run about 30-40 sec and shuts off as well. We can manually restart it after 5 min. Same thing happens again. Help!!! Thank you!
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Re: 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.
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Go up on the roof of the unit and remove the AC Shroud. With the unit running, see if you can pinpoint where the sound is coming from. The only thing on the entire AC that would make that much of a vibration would be the fan motor. Not sure what would cause the fan motor to do this. The compressor may do that but only if the windings are bad and then it would not be cooling.
I don't think these little units have a start capacitor but what I would do is check that the on/off switch wires to make sure they aren't loose. Also check the wires to the compressor for loose wires as well. It is possible that these are the first signs that the compressor is about to fail. They also can act up some when they haven't been used for awhile and then you try and start them up. Try running the unit for a few hours without asking it to cycle. It might just be a sticky valve.
I had a problem with my coleman mach 3 AC, we were at an RV park up at lake shasta CA and the fan would stay on but the compressor would come on for a few seconds and then trip off. It was the motor overload relay on the compressor that was tripping. the RV park was old and apparently the wiring to the panelboard at the RV park was too small, when you are drawing a lot of current there was too much voltage drop across their line, to make up for this the motor tries to draw more current and heats up the motor overload and it trips off. I solved this problem by buying an autoformer from Camping World, it senses a voltage drop and automatically boosts the voltage.
I am now having a seperate problem, the compressor is either locked up or has too much back pressure and trips off the service breaker when trying to start. The only solution I can see with my current problem is to replace the entire unit.