Furnace down.

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tregrad

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Gary helped me with this question on another thread I invaded so i moved my question here. i have a 2012 keystone sprinter with a suburban furnace, when i turn it on at the thermostat, i hear a click at the thermostat and then a click where the furnace is and then zero, zip, nada.
model # sf-30FQ>

this was Garys response:
The click at the furnace is the fan relay closing to start the fan, but apparently the fan isn't running. Nothing else can happen until the furnace fan reaches an adequate speed. At a guess, either the fan has failed or the fan relay (on the circuit board) did not actually deliver 12v power to the fan.
 
Thank you for your help gary, my question now is what would you go after first? is the fan relay and easy fix or is it soldered to the board in which case do I have to basically get a new board?
do you have a good spot on the internet to buy parts? camping world is just out of line.

again thanks for your expertise. if you ever need any help with your tile in your house let me know lol
 
I drive a f350 and was told to hook jumper cables to the trailer battery and see if the furnace fan started and no go. im assuming i do have adequate 12v power.
 
The 12 volts that passes through the thermostat and on to the furnace is not the same 12 volts that operates the fan.  Yes, it comes from the same source (battery), but both likely have separate fuses.  Check your 12 volt fuse panel before you get too deep.  The best way to test fuses if you don't have a meter is to simply replace them.  If that doesn't fix your problem, it's time to get out a meter.
 
12v fuse panel? i checked all my fuses in the panel and in the thermostat. i am hearing a clicking sound at the furnace after i hear a clicking in the thermostat. all fuses check out visually but that doesnt meant that im not seeing the defect.
seeing that the thermostat tries to make the furnace turn on i would doubt that the fuse is the issue but i do thank you for the input for sure, any other ideas would be awesome.
is there a fuse on the blower? or one that requires removal of the furnace? im gonna pull it tomorrow after i put a ball valve on the gas line so we can still cook etc.
 
tregrad said:
12v fuse panel? i checked all my fuses in the panel and in the thermostat. i am hearing a clicking sound at the furnace after i hear a clicking in the thermostat. all fuses check out visually but that doesnt meant that im not seeing the defect.
seeing that the thermostat tries to make the furnace turn on i would doubt that the fuse is the issue but i do thank you for the input for sure, any other ideas would be awesome.
is there a fuse on the blower? or one that requires removal of the furnace? im gonna pull it tomorrow after i put a ball valve on the gas line so we can still cook etc.
Click to expand...
If you have a digital thermostat, the click you hear is the thermostat switching on and the click you hear at the furnace is probably (as Gary said) the voltage from the thermostat being applied to the fan relay.  That does not necessarily mean the furnace has the 12 volts required to actually run the fan.  The thermostat cannot handle the current needed to run the fan, so it activates a relay (click) which applies a higher current capable circuit to the fan.  That circuit will be fused separately from the thermostat.  That's why I suggested checking the fuses first.  There may also be an in-line fuse in the furnace itself, but that will require some digging to access.


All that said, you may well have a bigger problem, but I was just trying to suggest where to start.
 
The next steps:
1. Measure the voltage to the furnace to be sure it is at least 12.0.  Should be 13+ if connected to shore power, and 12.0+ if on battery.
2. Jump +12v direct to the fan to see if it spins up. If yes, then the problem is the fan relay, which is part of the board. Just replace the board.  If no, replace the fan.  Amazon & Ebay have them.
 
Molaker said:
If you have a digital thermostat, the click you hear is the thermostat switching on and the click you hear at the furnace is probably (as Gary said) the voltage from the thermostat being applied to the fan relay.  That does not necessarily mean the furnace has the 12 volts required to actually run the fan.  The thermostat cannot handle the current needed to run the fan, so it activates a relay (click) which applies a higher current capable circuit to the fan.  That circuit will be fused separately from the thermostat.  That's why I suggested checking the fuses first.  There may also be an in-line fuse in the furnace itself, but that will require some digging to access.


All that said, you may well have a bigger problem, but I was just trying to suggest where to start.
Click to expand...

Thank you very much molaker
 
Another thing to consider if you have to get a new board is Dinosaur Board.

http://www.dinosaurelectronics.com
They are supposed to be more robust than factory. I have one in my furnace, and am satisfied with it.
 
Gary RV_Wizard said:
The next steps:
1. Measure the voltage to the furnace to be sure it is at least 12.0.  Should be 13+ if connected to shore power, and 12.0+ if on battery.
2. Jump +12v direct to the fan to see if it spins up. If yes, then the problem is the fan relay, which is part of the board. Just replace the board.  If no, replace the fan.  Amazon & Ebay have them.
Click to expand...

thanks Gary, my trailer is hooked up to a power pole at a camp ground and been living in it for a couple years. I think thats what you meant by "shore power"?

ok i have it out and how do i jump it to see if the blower is bad or the board? i have 2 blue wires a red and a yellow going into the unit.
 
furthermore when i pulled it out there was an on-off switch that was in the "off" position i can take a pic of it if you need it.
 
Gary RV_Wizard said:
The next steps:
1. Measure the voltage to the furnace to be sure it is at least 12.0.  Should be 13+ if connected to shore power, and 12.0+ if on battery.
2. Jump +12v direct to the fan to see if it spins up. If yes, then the problem is the fan relay, which is part of the board. Just replace the board.  If no, replace the fan.  Amazon & Ebay have them.
Click to expand...

how?
 
tregrad said:
furthermore when i pulled it out there was an on-off switch that was in the "off" position i can take a pic of it if you need it.
Click to expand...

Before you pulled it out, did you turn this switch on and try it again?  That is a service switch, and the furnace won't run with it off.
 
Yes, "shore power" means plugged in to an external 120v power source.

That switch must be on for anything to work - see Old_Crow's reply. However, I don't see how you heard a click at the furnace if that switch was off.

To test the fan motor, apply 12v directly to the wires to the fan itself. There will be only two wires to the fan motor, red & black, but different Suburban models may use different colors. Use some spare wire to get the +12v and -12v direct from the battery terminals or from a known good source on the trailer.
 
tregrad said:
Gary helped me with this question on another thread I invaded so i moved my question here. i have a 2012 keystone sprinter with a suburban furnace, when i turn it on at the thermostat, i hear a click at the thermostat and then a click where the furnace is and then zero, zip, nada.
model # sf-30FQ>

this was Garys response:
The click at the furnace is the fan relay closing to start the fan, but apparently the fan isn't running. Nothing else can happen until the furnace fan reaches an adequate speed. At a guess, either the fan has failed or the fan relay (on the circuit board) did not actually deliver 12v power to the fan.
Click to expand...
I had this problem with our 5th wheel.  It started about 6yrs ago, turned out to be a mud dauber line.  After getting that cleared out (lucky) it still periodically over the years would not start after a long sitting period.  If i smacked my hand on the outside of the trailer right when it clicked, it would start.  Last year I ended up taking the inside panel off and lightly tapped with a rubber hammer on the furnace itself, the problem has not come back since.  This spring all is well after sitting all winter. 
 
Old_Crow said:
Before you pulled it out, did you turn this switch on and try it again?  That is a service switch, and the furnace won't run with it off.
Click to expand...

Yes i did and no go. Thanks
 
Gary RV_Wizard said:
Yes, "shore power" means plugged in to an external 120v power source.

That switch must be on for anything to work - see Old_Crow's reply. However, I don't see how you heard a click at the furnace if that switch was off.

To test the fan motor, apply 12v directly to the wires to the fan itself. There will be only two wires to the fan motor, red & black, but different Suburban models may use different colors. Use some spare wire to get the +12v and -12v direct from the battery terminals or from a known good source on the trailer.
Click to expand...

not to be stupid but, Red Power and Black ground?
 
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