Furnace Issues

[billfoot]

I have a Passport 3350BH and decided to kick on the furnace tonight to make sure it is working properly before an upcoming trip next weekend.
When the thermostat is set to furnace and the temperature is set to activate, the furnace kicks on. I can hear the fan run, the igniter start up and the roar of gas. After about 30 seconds, instead of the blower starting up, I get a buzzing in the A/C unit and in the area of the furnace (which is under the stove.) It does this constantly until I turn the thermostat off. I have tried this with the A/C unit fan setting to High and Low instead of Auto. The furnace starts up but the blower never starts. Instead the A/C fan cuts in and out in rhythm with the buzzing.
We used the furnace last year and it almost ran us out it got so warm. I took the unit in for a recall repair on the A/C unit in the spring but had not tried the furnace until tonight.
Any suggestions outside of carrying back for service?

[travelin texans]

The only connection between the furnace & ac is the thermostat. The fan switch on the thermostat does not control the furnace fan, the ac fan is 120 volt, the furnace is 12 volt. Is your battery fully charged, the furnace requires 12 volts to power the control board & run the fan, it may have enough to power the cb but not enough to start the fan.

[Ken / Claudia]

Maybe your system is different then anyone I have ever had. How This TT furnace works, Turn thermostat to auto, system on heat, set temperature. Furnace blower/fan come on 1st. igniter lights propane. The air blowing out the heat ducts turns from cold to warm or hot. No other blower comes on. Nothing to do with the A/C.

[chuckster57]

I wonder if the tech that did the recall didn’t do it wrong.

[shiggs68]

Not sure what your A/C Recall was but the thermostat connects to the A/C control circuit board which then connects to the two furnace wires to call for heat. The circuit board could be bad or not connected correctly. To verify the furnace, open it and jumper the two blue wires. That will call for heat regardless of the circuit board or wiring.


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[travelin texans]

Originally Posted by Ken / Claudia

Maybe your system is different then anyone I have ever had. How This TT furnace works, Turn thermostat to auto, system on heat, set temperature. Furnace blower/fan come on 1st. igniter lights propane. The air blowing out the heat ducts turns from cold to warm or hot. No other blower comes on. Nothing to do with the A/C.

I've had several rvs & the thermostat indeed operates both ac & furnace, set to "heat" the furnace ignites & once it reaches a default temp for the sail switch the fan starts moving warming air. Set it to "ac" & set the fan to "on, hi, low, or auto", "auto" is so when the ac starts/stops so does the fan, set at "hi/low" adjusts ac fan speed, set to "on" the fan will run constantly at whichever speed it's set at. The fan setting on the thermostat does not control the furnace fan, it has 1 speed "on". Setting the thermostat to "auto" it will not switch from ac to furnace. This how every rv I've owned operated, with exception of my current that one ac is also a heat pump so the t-stat settings are different.

[Ken / Claudia]

This is TT and the last one have a wall mounted thermostat that controls both a/c and heat I believe that is normal but, not both on at the same time. It sounded like the OP said the furnace was on and the A/C came on making a strange sound.
But, like I said his could be different. Question I have does anyone have a furnace that has a fan and blower. He said the fan came on then the blower. Also could be but, not what I have had or seen.

[billfoot]

I wanted to follow up with the solution that fixed my furnace issue last week. In December, I received a second notice on a wiring recall on my A/C unit (not the furnace). I thought my dealer had taken care of this on a visit in May 2017 and had not turned it in. I called Keystone to find a closer dealer than Indiana since I am in Tennessee and after getting some names, I took it to a local dealer. They got me in and out in less than a week. During my pickup and paying for some other work, the lady said they opened up the A/C wiring and it looked like someone had “done” the recall but it turns out, they did it wrong, which ended up being the issue with the furnace. So the issue was a bad wiring repair which explained the “buzzing” sound I heard when the furnace tried to turn on the blower. I brought it home and checked and everything is now working.