Furnace wont run

tjasick · 09-24-2015, 10:47 AM

I have a 2014 Sunseeker 2860 with a Suburban Furnace and a Dometic LCD Thermostat. A/C works great but when I turn it to Heat nothing happens except a faint click from the furnace area. Fan does not come on. Running on Shore power. Checked voltage at themostat and got 12.6 volts DC, 13.8 at coach battery. Stove runs fine with all three burners showing blue flame. Fridge runs fine on gas also. Is there a fuse somewhere other than the Panel which shows all fuses and breakers closed. Help, cooler weather is coming.

**Bama Rambler** · 09-24-2015, 11:09 AM

Has it worked up until now?

If so it sounds like it's not sensing the sail switch being open. If it senses the sail switch being closed when it's not running then it won't try to start. That's where I'd start looking.

tjasick · 09-24-2015, 11:18 AM

We got it late last June so we did not have a need for heat until now. During the walk through we were shown how to set the thermostat to heat but never saw the furnace run, it was in the mid 90's that day.

tjasick · 09-24-2015, 11:19 AM

Sail switch will not work since the fan never comes on.

bubbles · 09-24-2015, 11:32 AM

Quote:

Originally Posted by Bama Rambler

Has it worked up until now?

If so it sounds like it's not sensing the sail switch being open. If it senses the sail switch being closed when it's not running then it won't try to start. That's where I'd start looking.

Yes, it is the sail switch not being actuated but as said the sail switch is actuated by the fan blowing air on it. When there was the click sound the fan should have come on, I believe and then a short time later the heater should have fired up. The thermostat must be set to a high enough temperature setting for the furnace to come on. There is a delay from furnace on to hearing the fan.

Toby · 09-24-2015, 11:52 AM

This happened to me a few years ago. My dealer told me to take the cover (cosmetic louvre) off and knock on the furnace a few times. I thought that sounded odd but I tried it anyway. Furnace kicked right off. A few weeks later they replaced the sail switch under warranty (you get two years on the furnace from the manufacturer). It's an easy test.

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tjasick · 09-24-2015, 12:21 PM

Thanks for the suggestions, I'll try tapping on the furnace and post results

**Bama Rambler** · 09-24-2015, 01:08 PM

Here's what's supposed to happen with the sail switch. When the t-stat calls for heat, the start relay engages and the control board checks the sail switch to make sure it's not on. If it's not on, then it starts the blower and checks to see that the sail switch closes. If that happens it then waits for the purge time to expire and then it energizes the igniter, opens the gas valve and then checks for a flame.

The reason it initially checks to see if the sail switch is open is for safety reasons. If the switch is closed when the blower isn't running then there's something is wrong with the switch and it can't let the unit start.

If it didn't check the position of that switch prior to starting the blower it could potentially start the igniter without airflow through the system and cause a possible explosion due to lack of purge.

Ditchdigger · 09-24-2015, 02:31 PM

Mine had a problem not starting about a year go, it was getting cold and it did not work for about three days. I did not know what was going wrong, all it was is a air lock in the gas line and would not let it the furnace fire, it finely worked its way out and started firing.

tjasick · 09-24-2015, 02:40 PM

Removed wood cover under fridge to gain access to furnace. Removed front metal cover of furnace, can't see anything but outside of burner chamber, blower and all wires are in back of furnace and not accessible without removing the furnace. Tapped on furnace as far back as I could reach. Still nothing when thermostat is set to heat.

**Bama Rambler** · 09-24-2015, 03:45 PM

It's a bummer that they don't install the units to where you can access them. You're most likely going to have to remove it in order to finish troubleshooting the problem.

Ditchdigger · 09-24-2015, 08:13 PM

Quote:

Originally Posted by tjasick

Removed wood cover under fridge to gain access to furnace. Removed front metal cover of furnace, can't see anything but outside of burner chamber, blower and all wires are in back of furnace and not accessible without removing the furnace. Tapped on furnace as far back as I could reach. Still nothing when thermostat is set to heat.

Sounds just like mine, can't get to it without removing the fridge. How long have you been trying to light it?

**Herk7769** · 09-24-2015, 08:26 PM

Yes, there is another current limiter on the floor near the back of the heater.
Looks like this.

tjasick · 09-26-2015, 09:44 AM

Thanks for all your comments and suggestions. Since I do not have the tools or desire to remove the furnace I have scheduled an appointment with a service company. I'll post the results when it is fixed, probably will take up to 2 weeks, everyone is heavily booked for fall repairs.

tjasick · 10-02-2015, 10:05 AM

Just got it back from service. Apparently wire from thermostat runs to a/c unit then to furnace. Service guy found loose connection in a/c to furnace wire. Did not have to pull furnace so bill was only $50. You know I will use Annapolis RV for service in the future.

Toby · 10-07-2015, 07:39 AM

Awesome!

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