Transfer Switch?

Secarider · 09-13-2019, 01:56 PM

Hope someone can chime in. 2017 329DS, Went to turn on front AC this afternoon and nothing, thermostat light moves as I push the button nothing comes on (AC/Heater
Go to the bed room turn thermostat on to ac and it operates great. I am on shore power 50 amp. Disconnect shore power and start generator and front ac works great, also rear ac.
Is this a transfer switch issue. You tube examples show opposite, wont work on generator problem but will on shore power.
What I don't understand is why does the rear ac work and not the front? I don't have them switched on at the same time. Does one leg of transfer switch power one ac and the other leg power the other ac?

bubbles · 09-13-2019, 03:22 PM

Yes, one leg for the front A/C and one leg for the aft A/C. If you look at your power panel you will see the 2 circuit breakers (one for the front and one for the back) each is on a separate bus. The transfer switch (contactor) is deenergized if shore power is applied and it is energized if the gen power is applied. The gen has priority which means that if you have shore power applied and start the gen the switch will automatically switch over to the gen input. I suppose one of the contacts within the switch could be arc welded to the energized side or perhaps it is not fully deenergizing. Shore power is a 2 leg input and the gen has a single leg output and is split to provide the 2 power busses with power. In this way the 2 power busses remain separate no matter what the power source. This is just a down and dirty explanation.

Secarider · 09-13-2019, 03:44 PM

Thank you for the explanation. I do appreciate it. So I went and took the cover off the transfer switch and now I know what the clicking noise is when I plug in shore power. So I pushed the generator side of the transfer switch which caused it to click on and off. Now AC turns on and off every time. At least the 5 times I tried it. I either have something going bad or it just got stuck when I turned the generator off the last time. I could have forgot to turn the AC off prior to shutting down last time. Not sure. I think I will go order a new transfer switch. Just in case.

wrapperman · 09-13-2019, 04:24 PM

On my transfer switch I have 2 relays. One is for the generator and the other is to switch on the shore power.
Two things come to mind.
DO THIS ONLY IF YOU ARE FAMILIAR WITH HIGH VOLTAGE ELECTRICITY!!!
If you manually push the shore power relay and your front ac works, then the relay contracts may be bad. The contracts may be able to be cleaned.
Second is, when on shore power and the front ac is not working do you have other outlets not working which would indicate other problems.
Transfer switches are an inexpensive fix.
When you fix your issue please post your fix.
BEFORE YOU WORK ON THE RELAYS PLEASE, PLEASE UNHOOK FROM SHORE POWER AND THE GENERATOR IS OFF.

Bill m · 09-13-2019, 06:33 PM

I had a similar thing happen twice this past spring. Both in the same campground, we asked to have the power checked and it was discovered one of the legs had dropped out on the campground.
It happened one more time about a month ago. This time my surge protector had one leg fused, it is suspected it fused do to the earlier incidents.
The symptom was no forward ac, and the rear ac working correctly.
The transfer switch operates correctly.

Hope this helps

bubbles · 09-14-2019, 08:17 AM

Quote:

Originally Posted by wrapperman

On my transfer switch I have 2 relays. One is for the generator and the other is to switch on the shore power.
Two things come to mind.
DO THIS ONLY IF YOU ARE FAMILIAR WITH HIGH VOLTAGE ELECTRICITY!!!
If you manually push the shore power relay and your front ac works, then the relay contracts may be bad. The contracts may be able to be cleaned.
Second is, when on shore power and the front ac is not working do you have other outlets not working which would indicate other problems.
Transfer switches are an inexpensive fix.
When you fix your issue please post your fix.
BEFORE YOU WORK ON THE RELAYS PLEASE, PLEASE UNHOOK FROM SHORE POWER AND THE GENERATOR IS OFF.

In actuality I think the OP has the same set up with 2 contactors (relays) I believe to be mechanically interconnected so only one can be energized at a time with the gen relay having priority.

wrapperman · 09-15-2019, 12:38 PM

Quote:

Originally Posted by bubbles

In actuality I think the OP has the same set up with 2 contactors (relays) I believe to be mechanically interconnected so only one can be energized at a time with the gen relay having priority.

You're right. That's the way mine are. Only one relay can be energized at a time.
I would check to see if any other outlets are not working wnen the original poster is having his problem.
Then start at the relay and see if power is going into the relay and then coming out of the relay.

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