My rooftop a/c unit makes a compressor noise as soon I as plug in my travel trailer. It's a 2009 Outback Sydney edition 310 bhs with a dometic a/c unit I believe. basically with the thermometer switch to off position it sounds like a pump kicks on every 15 minutes or so and runs for 3-5 minutes then shuts off. The system blows cold air when turned to on position but also makes that sound between cycles. I really need to find out the cause. I switch the breaker to the off position when not using the a/c in order to keep this cycle from occurring. Any thoughts would be helpful. Thank you

SOURCE: PROBLEM WITH DOMETIC RV ROOFTOP AIR conditioner

Check at the compressor terminals between the Red and the terminal for the overload protector to see if you are getting power to the compressor on startup.

Perry Putnam

• 144 Answers
• Posted on Feb 26, 2009

SOURCE: coleman rooftop a/c coachman travel trailer

It's likely that the contacts are stuck closed. You can usually just tap them with a screw driver and they will open but then you should replace them. If you don't know where they are. Find the power wires coming inside the unit and follow them. Contacts are fairly easy to replace as long as you do it wire for wire. In other words when you remove a wire from the old attach it to the new before removing another. I hope this helps. Please don't forget to give me a Fixya rating.

SOURCE: Breaker breaks

This unit may have an internal overload mounted on top of the compressor. You would have to get to the
compressor to find out and it maybe faulty. That may
explain why the compressor comes on later on, this
overload protects the compressor from getting hot.

When you trip the breaker and then reset it again only to see it trip again almost sounds like a direct short or loose wire. It could also mean that your
capacitor needs to be replaced or that you need a hard start kit and the unit needs a good cleaning.

Try just operating the fan and see if it trips the breaker, if it does then either the blower motor is bad
or it is still the capacitor.

Testimonial: "The blower fan works fine. The breaker only trips when a load is put on it, but not always. I think the overload protecter could be the problem. Thanks."