No power except microwave when plugged into shore power.

[jx2young]

In trouble shooting we found battery disconnect switch blowing one of two 5 amp fuse on 12 amp system relay? Any help is greatly appreciated!

[ronfisherman]

Closing thread.
Please reply to thread in Tech Issues.

[Ivylog]

The rubber mat burned the coil up and it's blowing the protection fuse. Here is a $58 replacement and says it's a latching relay... only requires a short pulse of power to activate. Connect the two big cables either side together and you will be fine until you can replace it.

[Snowman9000]

I agree with DrewE.

[DrewE]

Ah...probably the floor mat was pressing the switch continuously, and the coil (which is only rated for intermittent operation) got hot and shorted.

The solenoid you pictured is the actual battery disconnect. It's most likely toast. Bypass it by connecting both heavy wires on either side together on one of the side terminals. Do this with the 120V power unplugged and the 12V battery negative terminal removed from the battery. You'll have 12V power, but won't be able to turn it on or off with the switch until you replace the solenoid. In the meantime, you can turn it off by removing the negative lead from the battery if you need to store the trailer for a period of time.

If this is a trailer with electric brakes, do not pull the trailer with the battery lead disconnected, as the emergency breakaway brakes will not work in that case.

[jx2young]

Yes-if you look closely in the pic you can see the 2 -5amp orange fuses at the bottom left and right of the solenoid. I appreciate your help! We don't do electicity! Of course this happened last night and we are trying to get on the road today. One thing I didn't mention is that last night when I opened the trailer door I noticed the rubber floor mat was up against the battery disconnect switch. Now it doesn't work and we are blowing the left 5amp fuse.

[j-d]

Roger That. So then I concur with everybody else. Problem is 12VDC only. If you had 12VDC control voltage to the thermostat your A/C would also work.

I take it that the large terminal on the left side of the solenoid runs to the "12 Volt Disconnect" and the large terminal on the right leads to Battery Positive. If So...

Battery Connected: Do you have 12VDC between the large terminal on the right side of that solenoid, and Ground?
Battery Disconnected and Shore Tie Unplugged: Do you have Continuity (Zero Ohms) across the two terminals of "12 Volt Reset?"

Where are those 5A fuses? In the circuit of the small "+" and "-" terminals on the solenoid?

[jx2young]

Yes it is a wall mount controlled ac unit. Kib LR9806 us model.

[j-d]

OK, is this air conditioner controlled with a wall thermostat, or with knob controls on the unit itself? I'm asking about the 120VAC/Shore Tie aspect of it because you said you have power to Microwave and nothing else. Now it seems it's Microwave and Outlets. There could be power to the A/C but it won't run if it's on a wall thermostat. Should run if it has on-board knobs, like an old window unit.

If you provide Make/Model of the 12V relay pictured, we can probably find the wiring diagram for it.

If it was mine... I'd test for 12VDC to one of the big terminals. If there's nothing there, there's nothing for the rest of it to turn on.

[jx2young]

Here is a pic the 5 amp fuse on left is the one that blows when trying the battery disconnect switch.

[DrewE]

I assume the 5A fuses are for the relay's coils. (This typically is a latching relay, with a momentary dual-throw switch to turn it on or off.)

That would suggest that there's a short circuit in one of the coils for the relay or in the wiring to it. If it's the coil, presumably replacing the relay would be required. If the wiring, obviously correcting the short is needed. You should be able to figure out which it is by disconnecting the control lead(s) in question from the relay and measuring things with an ohmmeter. The relay coil should have at least 2.5? to 3? resistance, assuming the fuse is appropriately sized. Some analog meters might have trouble being very accurate at such low resistances.

EDIT: If you are willing to (temporarily or permanently) do without the 12V disconnect, you could bypass the relay by connecting the two heavy wires on it together on the same stud. Disconnect the negative terminal of the battery before doing this and make sure it's not grounding out before reconnecting the battery.

[jx2young]

We have no power to lights, refrigerator etc...when running on 12 volt system. Some outlets seem to be working.

[Snowman9000]

I don't see it as a transfer switch problem. I see it as the entire 12v system being unavailable. You're not getting power from either the converter or the batteries. The batts do not rely on a transfer switch, which is for the 120v side of things.

To be more clear, do you get 12v power when NOT plugged in to shore power?

[jx2young]

This is a horse trailer with living quarters that runs on a 30 amp system. Only 1 air-conditioner. We have 2 12 volt batteries for system off shore power. Hope this helps.

[j-d]

That'd be a Transfer Switch issue if you have one of those. Do you?

Do you have a 30A coach or a 50A?

And, do you have some kind of "load shedding" device? Some coaches with two A/C units have a device (or even simply a Switch) to allow only one A/C to run at a time.

Check all your 120 VAC breakers.