Comments on: Furnace Troubleshooting (the first step) http://rx4rv.com/archives/17 RV Service Resources and Opinions Wed, 09 Jul 2008 04:03:56 +0000 http://wordpress.org/?v=abc By: Doug S. http://rx4rv.com/archives/17#comment-4387 Doug S. Tue, 03 Jun 2008 00:58:03 +0000 http://rx4rv.com/archives/17#comment-4387 My thermostat does control the rooftop A/C as well. I guess I will test the sail switch and the limit switch for voltage drops, what would you say is maximum acceptable across both these components? Is it safe to say my circuit board is operational with no issues or may I have an issue there? My thermostat does control the rooftop A/C as well. I guess I will test the sail switch and the limit switch for voltage drops, what would you say is maximum acceptable across both these components?

Is it safe to say my circuit board is operational with no issues or may I have an issue there?

]]> By: Doug S. http://rx4rv.com/archives/17#comment-4386 Doug S. Tue, 03 Jun 2008 00:54:40 +0000 http://rx4rv.com/archives/17#comment-4386 My thermostat does control the rooftop A/C and the furnace. So I start by inspecting the limit switch(inside the furnace) and then the sail switch. What would the normal voltage drop across these components be? Is it safe to say seeing how the system works with the truck hooked up that the circuit board is OK? My thermostat does control the rooftop A/C and the furnace. So I start by inspecting the limit switch(inside the furnace) and then the sail switch. What would the normal voltage drop across these components be?

Is it safe to say seeing how the system works with the truck hooked up that the circuit board is OK?

]]> By: Chris http://rx4rv.com/archives/17#comment-4381 Chris Mon, 02 Jun 2008 12:33:43 +0000 http://rx4rv.com/archives/17#comment-4381 Hi Doug, I would bet that there is a voltage drop somewhere in the system- probably several, so even when the batteries are still up, the voltage to the circuit board gets low enough that it will not operate correctly. *If* the wall thermostat only works the furnace (and not the rooftop air conditioner), I would start there, but I've seen a lot of limit switches (which you access by removing the inside cover) with enough oxidation to severly drop the voltage- as well as the sail switch. Hi Doug,
I would bet that there is a voltage drop somewhere in the system- probably several, so even when the batteries are still up, the voltage to the circuit board gets low enough that it will not operate correctly.
*If* the wall thermostat only works the furnace (and not the rooftop air conditioner), I would start there, but I’ve seen a lot of limit switches (which you access by removing the inside cover) with enough oxidation to severly drop the voltage- as well as the sail switch.

]]> By: Doug S. http://rx4rv.com/archives/17#comment-4375 Doug S. Mon, 02 Jun 2008 02:15:17 +0000 http://rx4rv.com/archives/17#comment-4375 Continued: I replaced the motor in my furnace, it was dirty and the bearings were rough. I figured this was my issue but it is not. Continued:

I replaced the motor in my furnace, it was dirty and the bearings were rough. I figured this was my issue but it is not.

]]> By: Doug S. http://rx4rv.com/archives/17#comment-4374 Doug S. Mon, 02 Jun 2008 02:12:55 +0000 http://rx4rv.com/archives/17#comment-4374 Chris, I have a suburban furnace in my 01 Sierra. I have had an ongoing issue with the furnace that is frustrating me big time. With fully charged batteries my furnace will run 2/3 through the night before it stops igniting and the fan runs cold. Last year my converter went on the fritz and I figured it wasn't charging the batteries good enough. This year I installed a PD power distro center with the charge wizard. I still get the same result from my furnace. If I plug my truck into the trailer the furnace will run all night but if it runs off my batteries alone it will stop 2/3 through the night. I have two deep cycle batteries that load test really well and through all this the lights in my trailer never go dim so batteries are not on my list. What is going on?? I replaced the blower motor Chris,

I have a Suburban furnace in my 01 Sierra. I have had an ongoing issue with the furnace that is frustrating me big time.

With fully charged batteries my furnace will run 2/3 through the night before it stops igniting and the fan runs cold. Last year my converter went on the fritz and I figured it wasn’t charging the batteries good enough. This year I installed a PD power distro center with the charge wizard. I still get the same result from my furnace. If I plug my truck into the trailer the furnace will run all night but if it runs off my batteries alone it will stop 2/3 through the night. I have two deep cycle batteries that load test really well and through all this the lights in my trailer never go dim so batteries are not on my list.

What is going on??

I replaced the blower motor

]]> By: nicole http://rx4rv.com/archives/17#comment-4334 nicole Sat, 24 May 2008 02:10:34 +0000 http://rx4rv.com/archives/17#comment-4334 i have a wall furnace(no idea what the make is) and it is controlled by a wall thermostat. it started to make a popping sound and than a ball of fire would come out from the grill. turned it off and cleaned it up, called the gas co and they said to let the dust burn. turned it on after it had burned clean and it popped and fire came through again. we have been using it for the past 7 years and never had this occur before. any idea what it could be? thanks i have a wall furnace(no idea what the make is) and it is controlled by a wall thermostat. it started to make a popping sound and than a ball of fire would come out from the grill. turned it off and cleaned it up, called the gas co and they said to let the dust burn. turned it on after it had burned clean and it popped and fire came through again. we have been using it for the past 7 years and never had this occur before. any idea what it could be? thanks

]]> By: Doug H http://rx4rv.com/archives/17#comment-4325 Doug H Wed, 21 May 2008 21:40:45 +0000 http://rx4rv.com/archives/17#comment-4325 Follow-up: Is the relay inside the furnace by the blower motor? No access door from the outside. Will there be 2 wires on the blower motor that I can hook 12v to, and is the white wire the ground on the furnace also? Follow-up: Is the relay inside the furnace by the blower motor? No access door from the outside. Will there be 2 wires on the blower motor that I can hook 12v to, and is the white wire the ground on the furnace also?

]]> By: Chris http://rx4rv.com/archives/17#comment-4323 Chris Wed, 21 May 2008 18:02:43 +0000 http://rx4rv.com/archives/17#comment-4323 Hi Doug, It sounds like either the blower motor or the fan relay. I would hook 12 volt power directly to the blower motor to see if it will run OK (make sure the blower will turn freely, as well). If the furnace has the outside door, you should be able to do this without pulling the furnace out (IIRC). Hi Doug,
It sounds like either the blower motor or the fan relay. I would hook 12 volt power directly to the blower motor to see if it will run OK (make sure the blower will turn freely, as well).
If the furnace has the outside door, you should be able to do this without pulling the furnace out (IIRC).

]]> By: Doug H http://rx4rv.com/archives/17#comment-4320 Doug H Wed, 21 May 2008 00:32:40 +0000 http://rx4rv.com/archives/17#comment-4320 Chris: Have a Suburban SF-35F furnace in an 05 Hornet Retreat. Has worked fine for the last 3 years until last weekend. Turned furnace to Heat and instead of the blower coming on and running for 30 seconds to 1 minute before igniting all we got was a buzzing noise coming from the furnace. Turned furnace off and buzzing noise remained until approximately 1-2 minutes before buzzing noise turned off...almost like a blower cycle time. Waited about 30 minutes, turned back on, same buzzing noise occurred. Pulled furnace out, and with switch in heat mode buzzing noise occurred and noticed blower fan moving very slowly. Tried it the next weekend to see if there was any difference, furnace did nothing, no buzzing, no blower, nothing. Any ideas? Chris: Have a Suburban SF-35F furnace in an 05 Hornet Retreat. Has worked fine for the last 3 years until last weekend. Turned furnace to Heat and instead of the blower coming on and running for 30 seconds to 1 minute before igniting all we got was a buzzing noise coming from the furnace. Turned furnace off and buzzing noise remained until approximately 1-2 minutes before buzzing noise turned off…almost like a blower cycle time. Waited about 30 minutes, turned back on, same buzzing noise occurred. Pulled furnace out, and with switch in heat mode buzzing noise occurred and noticed blower fan moving very slowly. Tried it the next weekend to see if there was any difference, furnace did nothing, no buzzing, no blower, nothing. Any ideas?

]]> By: Rod Wesling http://rx4rv.com/archives/17#comment-4235 Rod Wesling Fri, 09 May 2008 18:58:57 +0000 http://rx4rv.com/archives/17#comment-4235 I have 86 winnie motorhome with Atwood 7912 Hydro Flame,blower(fan)runs continuously when thermostat is turn, on but no ignition(flame),gas is on,would you give me a step by step run down so I can find and correct the problem? Thanks Rod. I have 86 winnie motorhome with Atwood 7912 Hydro Flame,blower(fan)runs continuously when thermostat is turn, on but no ignition(flame),gas is on,would you give me a step by step run down so I can find and correct the problem? Thanks Rod.

]]>