Is the AC tripping my surge protector?

We've had our LM 365 Newport for about 6 months now with no electrical issues. The campground we are currently in seems to have decent electric - we haven't had any outages or low amp issues. Lately if we turn on the bedroom AC, the surge protector makes a loud thumping sound and shakes the trailer. The power comes on and off until we turn off the AC. There is no delay - just quick on/off/on/off. The other two AC units do not cause this problem. We can use the microwave, washer, dryer, etc. with no power issues. Has anyone experienced this loud thumping and shaking? Is it the surge protector "protecting" the trailer because the AC is causing a surge? Any ideas or advice would be much appreciated! We are nowhere near a dealer and are living in the coach for work, so taking it somewhere isn't really an option. We are hoping we can figure this out ourselves. Thanks!

Do you have a transfer switch? If so the hammering you hear may be the transfer switch banging. We had this happen and had to replace the transfer switch. If the voltage drops to around 104 volts the transfer switch will kick out and try to switch over to the generator (even if you do not have a generator). The banging can get loud to a point it will almost shake the trailer. Also the AC will kick off and on which could damage the compressor. Get it checked out right away before you damage the AC. Also you do not have to have a generator to have a transfer switch because it comes (transfer switch) with the generator prep. If you have found it to be the transfer switch you can call Heartland Parts if you are in warranty they might ship you a new one (they did me) and if you are able switch it out yourself. In the meantime you can wire it direct by removing the transfer switch.

Hi Coles,

LM 365 comes with a combination transfer switch/surge protector. You also have a Power Control System that manages the various loads to make sure you don't exceed available amperage from the campground power pedestal.

As Jim suggested, this sounds like power is dropping at the transfer switch when you turn on the bedroom A/C unit. It could be the transfer switch is starting to fail, or it could be loose/damaged wiring. It also can be a problem with campground power.

I would start with the campground power pedestal and make sure you're getting at least 115 V AC on each leg, and that the power cord connections don't show any burn damage.

If you are comfortable working with high current electrical, you might want to inspect the connections inside the transfer switch and also the connections at the circuit breaker panel. To get to the transfer switch, you'll have to take down the rear wall of the pass through storage area. CAUTION is needed if you open the transfer switch. There's enough power to injure or kill you if you make a mistake. I would disconnect the power cord from the campground power pedestal before opening the box.

Also, you'll find that in addition to a good volt meter, a non-contact voltage tester will help you verify what's hot and what's not. Get the $20 one - skip the less expensive ones.

If you don't feel comfortable troubleshooting this yourself, consider using a mobile servicer. You'll have to pay the travel time charge, but if you get advance approval, Heartland will probably cover the labor charges under warranty.

Dan and Jim.....I would agree with you if the issue occurred with any high load item starting up but the fact that it's only the bedroom A/C leads me to think the issue is with either the wiring for that unit or the A/C unit (bad start capacitor?) itself.

NWILSON said:

Dan and Jim.....I would agree with you if the issue occurred with any high load item starting up but the fact that it's only the bedroom A/C leads me to think the issue is with either the wiring for that unit or the A/C unit (bad start capacitor?) itself.

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It's a puzzling situation for sure. Further complicated by the Power Control System because the compressor power goes through a relay in the Power Control System.

But it's hard for me to see how the Air Conditioner could be the direct cause. If it were pulling too many amps, or had a short, I'd expect it to trip a circuit breaker.

If the transfer switch contactors are dropping, it seems more likely that something's pulling down the voltage on shore power L1 below 105 V or the transfer switch is beginning to malfunction. My thought is that the A/C unit is perhaps just pulling a little more power than the other devices and is the trigger event for a transfer switch running on the edge.