Geo Pro 16bh power issue

[cgrover]

Hi there. Just bought a used Geo pro 16bh and found out the heater won't work. The thermostat seems to not have any power at the wall, confirmed with a voltmeter. I have checked the main fuse box near the front door, and also looked around the furnace. Am I missing something? Duel 12v batteries are fully charged, also tried on shore power and still nothing. Help me keep the wife happy!!

[Bama Rambler]

Your furnace runs on 12 volts, so the first thing you need to do, if you haven't already, is find the fuse for the furnace and make sure it's not blown.

Is your thermostat for the furnace only, or is it for the furnace and A/C?

If it's furnace only, then take the wires off the thermostat and touch them together and see if the furnace runs. If it does then you have a bad thermostat.

[cgrover]

Originally Posted by Bama Rambler

Your furnace runs on 12 volts, so the first thing you need to do, if you haven't already, is find the fuse for the furnace and make sure it's not blown.

Is your thermostat for the furnace only, or is it for the furnace and A/C?

If it's furnace only, then take the wires off the thermostat and touch them together and see if the furnace runs. If it does then you have a bad thermostat.

So I have checked all fuses I can find and they are good. I do have a roof mounted AC, with dials to turn on and off, and adjust temp. So I'm guessing that its separate . Does it count that I used a copper wire and touched both thermostat wires? If so nothing happened when I did that

[Bama Rambler]

So your thermostat is for the furnace only.

Using a jumper is the same as touching the wires together, so the problem is elsewhere. Did you test the fuses with a meter or lighted fuse testor, or just look at them? A lot of times a fuse can look good and actually be blown.

If you tested the fuses then find the power wires going into the furnace and check for voltage right at the furnace, and then work back from there to see where you find power.

[cgrover]

Originally Posted by Bama Rambler

So your thermostat is for the furnace only.

Using a jumper is the same as touching the wires together, so the problem is elsewhere. Did you test the fuses with a meter or lighted fuse testor, or just look at them? A lot of times a fuse can look good and actually be blown.

If you tested the fuses then find the power wires going into the furnace and check for voltage right at the furnace, and then work back from there to see where you find power.

I just looked at them. I will look into some sort of tester for that. I was just secretly hoping there was a switch or something easy I was missing. Thanks for your help. My dealerships in Reno are booked out until 11/30!

[Bama Rambler]

You say in your first post that you checked for power with voltmeter. If that volt meter is a multi-meter you can pull the fuses and use the ohm function to test them. In fact most multimeters have a continuity beep function that makes testing fuses really easy.

Also, some furnaces have a switch on the case that can get turned off.

[cgrover]

Originally Posted by Bama Rambler

You say in your first post that you checked for power with voltmeter. If that volt meter is a multi-meter you can pull the fuses and use the ohm function to test them. In fact most multimeters have a continuity beep function that makes testing fuses really easy.

Also, some furnaces have a switch on the case that can get turned off.

Sorry I am working or i would look at my volt meter. Its a AC/DC that just detects what the draw is. Just before I tried it on my wifes battery and it clearly lit up the 12v lights. So I did the same thing to the two wires on thermostat. Trying multiple attachment points. Might be time to get a better/different one for this application?

[Barry Allen]

I have a 19 FD so probably the same furnace / thermostat / wiring, etc. I just did a deep dive on the furnace because my electronic thermostat blew up and because I had a wasp nest in the fresh air port.


There are only 2 wires on that thermostat. As another poster stated, hold those 2 wires together to complete the circuit. If the furnace starts, your thermostat is bad. Not start, you have a blown 12V blade fuse in the power converter panel or a broken wire or a problem inside the furnace. Hold the wires together for at least a minute because it takes some time for the furnace to start. You only have to wait for the fan to start to prove it is working, you don't have to wait for heat.


Most likely it is the fuse. Start there. If you don't have an ohm meter or multimeter to test the fuse, just swap the fuse with one of the others of the same color from that panel.

[DBGUY]

I had a similar issue with my thermostat on my 2018 Geo Pro 19FD. I could not turn on the heater when adjusting the thermostat. Checked fuses, wiring etc. I then removed the thermostat cover and checked the small thermostat switch. No wires broken but I found the switch case and been filled with sawdust from when the factory installed the thermostat on to the cabinet. The dust prevented the switch contacts from making a closed contact to operated the furnace. Once I cleaned out the sawdust, the switch worked correctly and was able to operate the furnace. Hope this helps!

[cgrover]

Originally Posted by Barry Allen

I have a 19 FD so probably the same furnace / thermostat / wiring, etc. I just did a deep dive on the furnace because my electronic thermostat blew up and because I had a wasp nest in the fresh air port.


There are only 2 wires on that thermostat. As another poster stated, hold those 2 wires together to complete the circuit. If the furnace starts, your thermostat is bad. Not start, you have a blown 12V blade fuse in the power converter panel or a broken wire or a problem inside the furnace. Hold the wires together for at least a minute because it takes some time for the furnace to start. You only have to wait for the fan to start to prove it is working, you don't have to wait for heat.


Most likely it is the fuse. Start there. If you don't have an ohm meter or multimeter to test the fuse, just swap the fuse with one of the others of the same color from that panel.

Man what a headache! So I have held the wires and nothing. I have since got down to the furnace wiring. I confirmed I have 12v at the red and yellow wires, just not the blue wires, which are thermostat. So what could be the connection issue there? The fuse bank and the red fuse on the furnace red wire are good

[cgrover]

Originally Posted by Barry Allen

I have a 19 FD so probably the same furnace / thermostat / wiring, etc. I just did a deep dive on the furnace because my electronic thermostat blew up and because I had a wasp nest in the fresh air port.


There are only 2 wires on that thermostat. As another poster stated, hold those 2 wires together to complete the circuit. If the furnace starts, your thermostat is bad. Not start, you have a blown 12V blade fuse in the power converter panel or a broken wire or a problem inside the furnace. Hold the wires together for at least a minute because it takes some time for the furnace to start. You only have to wait for the fan to start to prove it is working, you don't have to wait for heat.


Most likely it is the fuse. Start there. If you don't have an ohm meter or multimeter to test the fuse, just swap the fuse with one of the others of the same color from that panel.

is it odd that my fuses spark when i take them in and out. they are green ,20?

[NavyLCDR]

Originally Posted by cgrover

is it odd that my fuses spark when i take them in and out. they are green ,20?

That's normal.