Rapid switching noise in AC (power supply is off)

[kate_ervin]

Our rear air conditioning unit makes a rapid "switching" noise sometimes. We tried flipping breakers to make it go away. Today the problem has worsened. The Fan is turned OFF at the thermostat, temp control OFF. We even turned off shore power at the pedestal.

It's still switching, kind of going berzerk. We didn't think air conditioner would have any link to DC power??

NOTE: This is a 2004 model that came with 30 amp, but previous owner installed a secondary 50 amp electrical panel behind the original 30 amp (under the fridge).

So one question is, is it customary for the air conditioner "switch" to be wired into DC? Perhaps it's because the switch is connected to the thermostat, which runs the furnace, which CAN run on DC.

UPDATE: We found and pulled the fuse and the rapid switch has stopped.

Any insight would be appreciated, as we're not electric-savvy. Thanks in advance!

[dieselguy]

Your thermostat controls are 12V DC ... they control the 120V part of the A/C as in compressor and fan. Sounds as if you may have a bad thermostat.

[1retired06]

Certainly would be one of the first items to look at.

[kate_ervin]

Thanks for your replies. After putting the same fuse back in, the switching noise has NOT returned.

[DQDick]

By pulling the fuse you may have accidentally reset the thermostat. If it was have a brain issue that may have fixed it.

[kate_ervin]

Perhaps pulling and then replacing the fuse fixed the issue... whatever the issue was. Or maybe it was just a coincidence. The first time we pulled/replaced the fuse, the switching problem did continue. Only after a couple of different fuse pulls did the problem go away.

For what it's worth, this is an analog thermostat:



Perhaps it was the control board in the AC unit itself that needed to be reset.

Anywho, if we replace the thermostat, would you recommend sticking with the mechanical version or upgrading to a digital thermostat? I often consider digital stuff to be a downgrade, not an upgrade... But while researching this issue, most of the discussions I found were related to the digital Duo-Therm thermostats.

[kdeiss]

Several years ago I switch to a Hunter Digital that I picked up at Home Depot.
I got all the install info on this forumn was a great improvement you do have ad a switch for the two speed fan function not difficult to do I beleive if you search the net their is a derailed vedio out their on the install. I DO NOT RECOMMEND THE Dometic newer squire digital.

[kdeiss]

More info Hunter 42999B is the model google Rv Thermostar upgrade a detailed vedio

[kate_ervin]

Thanks for the recommendation on the digital thermometer that you upgraded to. You mentioned that you do NOT recommend the digital Duo-Therm thermostat, so it sounds like I will have to research that (on this forum?) to learn more about other people's experiences.

Thanks again, everyone!

[kdeiss]

What I do not like about the Dometic squire digital is no light to be able to read at night and zi question the accuracy