Dear Dave,
On our trip this weekend, after arriving at our campsite we found that the RV thermostat had no power. While looking for the problem, but wanting to bring in some fresh air, we also found that the fan for the vent had no power as well. Same thing with the vent in the bathroom.
There are no breakers that were thrown and we didn’t see any signs of fuses being blown. The labeling for both the breakers and fuses are extremely vague so we’re not even sure which fuse that it might be. This trip had times when we really could have used the A/C as well as some heat in the mornings. We would love to get this resolved before our next trip in a month, as it will be in a much warmer area. Thank you! —Tony, 2023 Sunseeker 3050S
Dear Tony,
From what I can tell, the distribution center is located under the refrigerator and should have both the circuit breakers and 12-volt fuses similar to this model.
The specifications on the website show a 15,000 BTU air conditioner and 30,000 BTU furnace, but not the brand. I assume it is Dometic, as Forest River is mostly a Dometic fan.
The RV thermostat is powered by 12 volts and should be one of the automotive plug-in style fuses. Your distribution center is much smaller with fewer fuses, so there are going to be some that power several components. Unfortunately, these are not labeled well in some RVs. As the unit goes down the line, 12-volt components are installed and not always connected to the same circuit, and just the main components are typically labeled. Some options are even spliced into existing wiring rather than dedicated runs, such as electric awnings, which we found on the Forest River Salem we have been working on.
Use a 12-volt test light or multimeter
I would recommend using a 12-volt test light or multimeter on 12-volt setting and doing an actual test on each of the fuses. Clip the ground to the metal frame of the distribution center and then touch each side of the fuse holder and it should light up on both sides. Or the multimeter should be at 12.6 volts unless you are plugged in.
It is very difficult to determine if a fuse is good or has continuity just by looking at it. You really need to use test equipment. My guess is there is a bad fuse. However, if not, then we need to start looking at other options.
Is the ground wire connected? The Salem we are working on has all the ground wires coming into the bottom of the converter and a large wire nut connects them to a pigtail wire going to ground. Two of the wires had disconnected. Notice the white bundle of wires underneath the automotive fuses. Verify the ground wire has a solid connection.
Have you verified other 12-volt components are working? If not, then it could be a battery disconnect switch or dead batteries. In this case, plug the unit into shoreline power and verify it is getting 12-volt power to the distribution center and beyond.
If everything else works, then it must be an open in a wire which can be verified by running a new positive or ground wire to the thermostat. Remove the thermostat and you should be able to temporarily power it with a jumper wire. The easiest way is to use a portable power source such as a cordless drill battery.
Running a dedicated line to the component will verify it is the component or the line. Since there are more items than just the thermostat that are not working, my guess is it is an open in the line, which could be a loose connection.
You might also enjoy this from Dave
Understanding everything about 12-volt house batteries
This is Part 4 of Dave’s “Everything you need to know about RVing” series. In this installment, Dave looks at 12-volt house batteries and tells you just about everything you need to know about them, whether this is your first or 101st RV trip.
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
Read more from Dave here.
HAVE A QUESTION FOR DAVE?
Send your inquiries to him using the form below.
##RVDT2458
I had that issue once, I found that the switch on the heater housing had accidently been turned off while doing some other work. I turned it back on and then had 12v to the thermostat.
Excellent article
I’m betting on someone turned off the “salesman switch” or more commonly known as the battery disconnect switch, I know on my RV if that switch is off most of my 12VDC is off like it’s supposed to be!
Snoopy
Thank you, Dave! The more I read, the more I understand. 🙂 Unfortunately, there is much still to learn. 🤔 😯 Thanks again, have a great day, safe travels, and safe stays! 🙂
Take the ceiling cover off the air conditioner. Look carefully up in the inside and you will see a bunch of wires connected to the A/C. One of those has probably come loose.