AC and Fan not working

[marc2912]

In a 2015 DSDP 4312. We have 3 roof ACs and for some reason I started getting an E7 error on the #2 roof AC. I went to the breaker panel (coach one in bathroom) and one had tripped, reset it but still getting the error. This is plugged in to shore power, 50A service. I made sure when testing all other AC units were off. Still the same. It sounds like the compressor kicks on and then nothing else and kicks off and error. I did try to turn on just the fan (no AC) and it's not working either.

Wondering if there's some kind of starter relay or similar that could be the issue here, basically the fan won't kick on so the panel errors out. Thanks for any help.

 

[Rich W.]

Sounds more like a fan motor “run” capacitor although it could be other things including the fan motor. But capacitors are cheap and easy to swap so its an easy rule out. If your multi-meter has the function you could just test yours. As I recall there are two separate capacitors in my 15k Dometic heat pumps - one for the compressor and one for the fan. That’s where I’d start.

(Edited to reflect nomenclature correction)

 

[marc2912]

Sounds more like a fan motor start capacitor although it could be other things including the fan motor. But capacitors are cheap and easy to swap so its an easy rule out. If your multi-meter has the function you could just test yours. As I recall there are two separate capacitors in my 15k Dometic heat pumps - one for the compressor and one for the fan. That’s where I’d start.

I guess it's time to get up on the roof. Thanks

 

[Kevin D Pem]

Sounds more like a fan motor start capacitor although it could be other things including the fan motor. But capacitors are cheap and easy to swap so its an easy rule out. If your multi-meter has the function you could just test yours. As I recall there are two separate capacitors in my 15k Dometic heat pumps - one for the compressor and one for the fan. That’s where I’d start.

Always good to make sure the capacitor has no charge. Theory says it has a path to discharge but check first. Most often a capacitor shorts out internally, check for continuity swapping test leads to avoid the reading of a charge from your meter battery.

 

[Webz]

Be careful with capacitor. Their job is to store electricity. Don't be the ground when you discharge one.

 

[Rich W.]

Agree with the above - work within your qualifications. I often forget to consider that.

 

[richguy]

The fan motor does not have a start capacitor it is a run capacitor. They are not expensive. If its the run capacitor the motor will get hot and shut off on overload. This assumes that you have power to the motor and not a burnt or broken wire. (50 years as a HVAC)

 

[Rich W.]

The fan motor does not have a start capacitor it is a run capacitor. They are not expensive. If its the run capacitor the motor will get hot and shut off on overload. This assumes that you have power to the motor and not a burnt or broken wire. (50 years as a HVAC)

So with 50 years in HVAC, what would be the first ting you’d check? My guess was capacitor but Im a relative rookie with HVAC.

 

[richguy]

First check electrical power, then spend $10 for a new capacitor.

 

[TheLooks]

Yes, I had one the other day that had burned the neutral clean off in the communication box in the rooftop unit. In reality, a novice can swap parts and get lucky, but a knowledge of the types of voltages and how they flow is really necessary to troubleshoot. 12 volts DC is the commander and 120 volts AC does the work.