Top 20 Dometic Rooftop RV Air Conditioner Questions & Answers

Unsure if that is a refrigerator or an Air Conditioner. Please add information to your question as to the model, or whatever you can tell.

First replaced the thermostat then check on condenser unit that's outside .make sure the fan is running when compressor runs .if not there is your issue .If fan runs and compressor keep shutting off you might have a dirty coil so clean it out with water or you might have a leak in the system causing unit to shut off on low pressure .if this is the case you need to call a service technician .
Try simple things first like clean coil ,capicator and fan operation.

Don't really understand what you mean by roof top duct unit .if it's a roof top unit and water is leaking down your vent then you have a clogged drain line .

You need to get a different thermostat.you can change an analog thermostat to digital, but you have to replace the motherboard with a digital compliant one. You can't just change the thermostat. Your best bet is to put back the old thermostat or upgrade to a different compatable thermostat

Go to your heater and locate the circuit board inside. There is a 3 amp fuse that protects the board and it is a regular auto fuse and isn't made for any surges in the system. When you turned your generator on with the system on, chances are you surged the system and that fuse went. Breakers allow for surges where fuses don't

I think you checked voltage across the run capacitor, the brown and white wires. The voltage to the motor would be on the black and white wires And inside the motor, a thermal protection device opens the black wire, leaving no potential voltage to the other voltage line nor capacitor line ( brown and white are the same line).
The solution, varify that the motor is wired correctly, then that the capacitor value is correct, not weakened, that the motor vent holes are not blocked or obstructed, that the motor amps are not exceeded, that the motor bearings have no side play and not worn.
Before replacing the motor, make sure the wiring is correct, the motor and capacitor are not good.

sounds like it is miswired. actually try fan on with the heat on and see if the fan works. If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

Your unit have dirty coil.
Shut unit off and clean the coil also change filter for indoor unit .Unit is shutting off on high head pressure

I think you should try it out first to see.

It is possible that a sudden loss of power caused the fan to run backwards. Usually that happens to a compressor, not a blower but I can't think of any other reason. May consider installing a time delay (delay on break), right on the red to the tstat rather than yellow, to ensure everything is included in the delay. Most newer tstats have them built in, possibly upgrade tstat. If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

Make sure your tstat is programmed for electric, not gas. Or in the settings you want that the TSTAT CONTROLS THE FAN. If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

Is this tstat battery powered or does it have a common wire? How many conductors are inside the tstat? If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

If the unit is a 220v, you will see 110v on that unplugged wire you mentioned. If it is 110v system then you probably have a swollen or open capacitor. The lil black box on the control board is a micro relay. And they do act up in different ways. If it's clicking, normally, that tells me its working. If it's 220v, make sure you have 220v to the system. If you have 220v to the system, and no power goilg through the micro relay, you can try jumping by that relay. While it's plugged into the relay (both wires), touch the 2 wire ends together with the end of a screwdriver for a second or 2 and listen for the comp to start. If it does you found your problem. All this does is bypass the relay by connecting those wire together. I've seen these units not work, if there is 2 units on the roof, due to a safety that doesn't allow both to operate at the same time, and never found the reason why. Now if it's 110v, you'll need to dig a bit more, following your voltage. Source, line, load. The source volts enter, the line feeds to the switch(s), the load is the motor/comp. The capacitor is a round/oval metal cylinder with wires attached, and stores voltage so it must be discharged by shorting the terminals to each other or ground. POWER OFF FIRST! Be safe please. If its 220v and you only have 110, check the breaker(s). If the capacitor is swollen up on top, where the wires connect, or have this sticky oil coming out of it, it's damaged. More that likely its the board. Last 1 changed was $129 my cost, not the customers. And I had to rewire the unit a bit and change the tstat also. So if you end up buying a board, ask them about an exact replacement. If it's not, ask them if they can draw you a schematic to help. Hope this helps!

no this site does not sell anything take the rv to a caravan shop and have the ac specialist check for an after market unit that will fit most thermostat are alcohol filled tubes that pushes on a diaphragm that makes or breaks a circuit against a spring tension that is set by the knob so it is very possible that the ac manufacturer used a common make that will fit but you will have to go to places that retails units such as a caravan repair shop or an ac repair specialist shop

The humming sound is the motor trying to start, if you turn it by hand, usually they will run. it sounds like the motor for fan needs cleaning and oiling. God-Bless ya all!

Compressor is low on gas .

see the manual at Dometic 620515 321 Installation Instructions Manual

A frozen compressor can be caused by several things. One cause could be partial loss of refrigerant or being over charged by someone adding to the factory charge. Another cause for a frozen compressor might be poor heat transfer in the evaporator, which is where the cool air comes from. This is usually systematic of a dirty evaporator or poor air flow coming from the fan. Another cause for a frozen compressor is the system not turning off when it should. This problem is usually a result of a bad thermostat or the thermostat not turning off soon enough. JohnL I’m happy to assist further over the phone at https://www.6ya.com/expert/w._c61c997d7bf3e6ae

That would be depending on whether you could do it yourself, or whether you had to pay someone to do this. Please call some RV dealers, and price all of this. An opinion? Dometic is not generally known as the highest quality product. (I have had many.) The really important item is that you must be really sure to have watertight seals in place when finished. God bless your efforts.

From the distributor or manufacturer. Most coils are OEM parts designed specifically for the RV conditioner. JohnL I’m happy to assist further over the phone at https://www.6ya.com/expert/w._c61c997d7bf3e6ae