Coleman rooftop A/C not cooling

[JMonroe]

It's 88 degrees, humid, and one of our A/C units will not cool.

We've got good 50 amp shore power. The only thing using power right now is the residential fridge and a TV and the satellite reciever. I shut down the only other thing we had been using, the electric element in the Aqua Hot.

Should I be able to run all three units on 50 amps?

I've cleaned the air intakes (just how do they get so dirty in 1/2 a season of mostly weekends only?).

Any other ideas?

[TXiceman]

from living in the RV, you have to clean the filters about every 10 to 14 days of use.

What is the voltage in the trailer when you are trying to run the A/C units? You need a minimum of 108 volts for the A/Cs to run. If the voltage is low, you may be able to run one or even two, but probably not 3 units.

Put the water heater on non-electric, the frig on propane and turn off the inverter to help on the power consumption.

Ken

[Jackm]

If you have a good 50 amp source, you should be able to run all the appliance you want. After all, 50 amps provides 12,000 watts of available power. A 120 volt plug in meter should tell you if you have enough voltage.

You didn't actually indicate how or why your AC unit isn't cooling. Is the AC fan and compressor working okay? If so, have you cleaned the unit's evaporator and/or condenser coils? This can make a big difference. Dirty filters can restrict flow but the unit should still be cooling.

I would check the voltage first. I would then make sure that the compressor is working (cycling on) and that your fan is operating properly. Lastly, I would examine the condition of your AC's evaporator and/or condenser coils. If they are really filthy, clean them. Best of luck.

Jack

[RV Wizard]

We first need more information as to the exact scenario you have going on. To say, "it is not cooling", to me means it is running but not blowing cold air. If this is the case, can you tell by sound if the compressor is running? If you cannot, you can turn off everything, start the generator, unplug from shore power and turn on only the air conditioner in question. On your EMS panel you will be able to see the amperage drawn from the generator. Allow at least five minutes of operation for the air conditioner's time delay to elapse and start to build up head pressure if the compressor is actually running.
If after this period you only have a couple of amps, the compressor is not coming on line.
Several things can cause this.
Lets first start with checking electrical connections in the easiest access. Drop the ceiling return vents on all units and check the 12 volt connections on the control boxes, including the freeze sensors and data cables. Be sure all are clean and tight. Turn thermostat off and then after a few seconds back on and re-test. If no change, turn unit off and shut down generator. Still being unplugged from shore power remove the roof unit shroud and access panel where you will find wiring from control box to capacitors and PTCR (compressor motor starter). Bleed of any residual charge that may be on the capacitor with a high ohm scale meter. Inspect for burnt wiring or components.
If it looks ok, you will now want to check for voltage from the control box to compressor. You can use shore power or generator. Be sure to allow time for the time delay to elapse and check for power on the group of white wires on the common terminal of the compressor run capacitor and the red wire of start capacitor and from the white wires and black wire going straight to the compressor. You can pierce the black wire or get contact at quick connector on control box. Do you find 120 vac? If so, you will need to use a clamp on amp meter to determine if you have current flow or not and how much.
If not you have a control issue.
Let us know what you find up to this point. Usually, a problem will have been found but if not we are only 1/4 way through diagnosis and it is going to get more complicated.

[JMonroe]

It's an all electric coach. Can't switch the fridge to LP. The monitor shows good 50 amp shore power coming into the coach, 120 volts on both legs.

The fan was running, the compressor was not coming on. I've been watching the surge protector monitor window as I've been turning things on and off. It has one display for each leg and shows the amps being drawn on that leg. It looks like the front A/C is on one leg, and EVERYTHING else is on the other. Both rear A/C units and the Aqua Hot electric element, as well as the cook top and the microwave. I'm guessing the EMS is keeping the rear compressor from kicking in. Problem is, even if I shut everything else off, it seems to take forever for it to reset and allow the rear air to come back on-line.

I did get all three A/C units to kick in late yesterday, and they all worked through the night. This morning the rear A/C had shut down (compressor only) again and the temp is rising again (...and I have no idea why. Nothing other than a TV and a computer were being used). As I type this everything except a couple TVs is off and has been for at least 1/2 hour (used the cook top and a toaster to make breakfast). The front A/C is running, I had turned off #2. #3, the rear, still won't kick in. I just shut it off completely. I'll see if it will come back on after having been shut off for a while.

I'm definitely no expert, but I'm thinking this may be a combination of poorly thought out electrical installation and a touchy EMS???