Thursday, September 21, 2023


Ask Dave: What does an E7 error code mean on Dometic roof A/C?

Dear Dave,
The front Dometic air conditioner stopped working on my 2008 Airstream Classic 34’ and is showing an E7 error code. I can reset the breaker and turn the A/C on and it will run for a minute, but then it trips the breaker and shows the E7 error again. I am full-time RV living and cannot find any mobile service help in Melbourne, Florida. Thanks. —Larry

Dear Larry,
According to the Dometic Air Conditioner Service Manual, the E7 error code is an interruption of 120-volt power to the unit.

Questions for you

I do have a few questions for you: Are you running both roof air units at the same time? Are you connected to 50-amp power at a campground? Do you have a surge protector at the pedestal to show voltage and amp draw? Have you tried a different pedestal?

Answers to these questions can help isolate power draw and management.

Check return air filter and evaporator coil

The first thing I would look at is the return air filter and evaporator coil. There will be one behind the grill for the air return in the ceiling. Since you have an error code, then I assume it’s a ducted system with a thermostat.

A plugged air filter will restrict airflow and the amp draw can raise. The same thing occurs with a plugged evaporator coil.

Check voltage

If these are clean and you have good airflow, I would suggest checking the voltage at the campground source. This can help determine what the E7 error code means. You can use a multimeter or even a surge protector such as Surge Guard that will tell you what the voltage is as well as the amp draw.

If you do use a multimeter, here is what you should find at the outlet.

Older units may have higher amp draw

Since your A/C unit is more than 14 years old, it might not be as efficient and have a high amp draw at startup. You might also want a certified technician to verify it with a clamp-on amp meter.

Another option would be to install a SoftStartRV device, which you can read more about here.

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.

Read more from Dave here


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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.


  1. Made a pretty good living cleaning air conditioners. Especially this time of year with all the cottonwood seeds.
    You have to take a lot of stuff apart and a pressure washer works best but you got to get the coils clean and free of dirt, webs, and other airborne materials.
    With the condenser coils clean the amp draw decreases and cold returns

  2. There could be a possibility that the surge of the A/C unit is too much for the circuit breaker (CB) which S/B 20 amps. I had a problem in my house when we installed a new central vacuum. When you would go to use it, it would at times kick the CB. I asked the electric store if they made a slow blow CB and they told me no. I contacted SQ D engineering explained the issue. They gave me a CB part number. I ordered it and never had a problem after that. CB do go bad after a while. When working for the Army they would test them before reising.

    • Sq D makes a high magnetic trip breaker that allows motors to start with a heavy load and large inrush current. They cost about 3times the normal breaker. And breakers go bad if they are used as a switch. In that case you get a breaker with SWD molded into the case

  3. Hell, if you can’t find a RV tech, find an electrician for the electrical problem. After all it is just an AC circuit.
    If the circuit breaker keeps tripping, it has to be something in the circuit wiring drawing too much amperage in that circuit, or a short .

  4. If your AC components are dirty and restricts airflow, your fan motor will draw LESS amps. Less air flow equals less work being done equals less power required.

    • Bob, it’s confusing the way the question was worded and I also wondered where they are seeing it. I believe the person was referring to their surge unit at the pedestal since no a/c unit I’m aware of comes with a diagnostic readable message center.

  5. E7 means interruption of power. Your AC is drawing more power than the circuit breaker can handle and it trips. I experienced the same condition. It was drawing close to 20 amps and the breaker would get hot. The bearings were going and the motor was working harder, drawing more amperage and it was time to replace the unit.

    • My thoughts exactly, if it’s that old or that dirty it’s probably dying. A thorough cleaning may delay the inevitable, but they only last so many years.


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