Dear Dave,
My RV is plugged into power from my shed and the 120-volt system works except for the air conditioner. The 12-volt system does not work. It has solar panels also. I shut the battery disconnect off for awhile and turned it back on, but that didn’t do anything. All the breakers are on and have not tripped. —Mark, Cherokee Alpha Wolf 22SW-L
Dear Mark,
You need to get a multi-meter and verify power to certain components. First, check 120-volt power at the circuit breaker for your air conditioner as well as at the unit itself. You did not indicate what type of outlet you are plugged into, so verify you are close to 120 volts.
If you are plugged into a dedicated 30-amp outlet, you will have plenty of power for the 120-volt appliances and the converter to provide a charge to the batteries. However, a 20-amp residential outlet with other appliances might be a problem.
Check with multi-meter
Next, set the multi-meter to the 12-volt DC setting and check voltage at the house batteries with the unit plugged in and the disconnect switch closed, meaning power should be getting to the batteries from the converter. You should find at least 13.2 volts coming from the converter. If not, either your converter is not working, or your battery disconnect switch is staying open.
If you have 13.2 volts at the battery, follow the positive cable from the battery to the circuit fuse typically mounted to the frame. This should be a 30-amp circuit with two posts. Check voltage going in, and out, as this fuse could be blown.
Even though your roof air conditioner runs on 120-volt power, it needs 12-volt power for the thermostat, or if it is an all-in-one unit, the module board and temperature sensor called the thermistor. You should be able to verify 12-volt power coming into the module board. There should be a wiring diagram on the inside of the air chamber.
There should also be a 12-volt plug-in fuse in the distribution center that protects the line providing power to the roof air conditioner. Verify this is good and power is going to the unit.
You might also enjoy this from Dave
Powering your RV: Essential 120-volt electricity tips and gadgets for every RVer
This is Part 3 of Dave Solberg’s “Everything you need to know about RVing” series. In this segment, Dave looks at 120-volt electricity and tells you just about everything you need to know.
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
Read more from Dave here.
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Thank you, Dave! Very helpful, educational explanation, response! Thanks again, have a great day, safe travels, and safe stays! 🙂
re: Plugged in and AC not working. Had that issue about 7-yrs ago on my 120v/30a 17-yo rig, and finally removed circuit board in ceiling, noted 1 slightly loose push-on terminal and gave slight pinch w/ pliers to restore, plus noted slight corrosion on terminals. Inspected board, saw no issues, so reinstalled and all good since. Assuming any corrosion defeated in the R&R process that scratched the metal clean.
Replaced my EMERG START solenoid about three years ago and would occasionally use the rocker switch to also top off chassis battery if not driven for a while. After one charge event some months ago, noticed the solenoid no longer CLUNKED when activated, so ordered new part, and finally took all apart to access and test, and found an OPEN GROUND to coil on white ground wire. Crawling under to trace the white wire, found the factory screw head on the self-tapping screw had popped off and wire hanging in mid-air. Problem solved, all good, reassembled and tested.