Furnace blowing cold air only

[RollandBC]

Hi, I have a 1995 Prowler 22' and it seems like the furnace is only blowing cold air.
It does state there is an AUTO Igniter but I can't see the pilot or flame or smell gas.

[Old-Biscuit]

With fan running ....
Check the voltage OUT of Sail Switch to circuit board (white wire to yellow)
White is +
Yellow is grd

IF you have DC Voltage then circuit board could be the issue

[RollandBC]

Incoming voltage is 12.75
fan is freely spinning

[RollandBC]

so both batteries charged to 12.75
still will not ignite
fan just runs and runs

[enblethen]

Check furnace incoming voltage.
Check the fan to make sure it is spinning freely. Do this by spinning fan with your fingers. Of course with the fan shut off electrically!
Why is only one battery being charged?

[RollandBC]

ok so now 1 battery charged to 12.85v would not ignite it.
There is gas to the stove.
I did have the protection cover off to look at the sail yesterday but after putting back on last night it did fire up hence the rush to think it was solved.

[RollandBC]

2 batteries, Group 24, both brand new this year

[enblethen]

furnaces suck alot of battery power. How many and what group of battery(ies) do you have?

[RollandBC]

Well it seems like it needs more Volts than the 10.5 it says it needs to ignite.
This morning at 11V it would not ignite.
So I'm charging it back up to 12.5 and we will see then I guess.

[enblethen]

Glad you got it working!

[Old-Biscuit]

RollandBC wrote:
Problem solved
Thanks everyone for the help, I learned a lot about how the furnace works.
It's running hot!

Low DC Voltage....fan could NOT come up to rated speed to generate enough airflow to make up Sail Switch

[RollandBC]

Problem solved
Thanks everyone for the help, I learned a lot about how the furnace works.
It's running hot!

[RollandBC]

So I pulled the board ,blew the dust off
reinstalled
all connections look good
just topping up the 12V trailer batteries they were reading just over 10.2

[Old-Biscuit]

White and Blue wires sticking thru the motor cover go to sail switch
Blue is 12VDC+ from thermosyat to timed delay relay & sail switch
White is 12VDC+ from Sail Switch when is closes....goes to circuit board

White wire at connector should have 12VDC+ IF sail switch closes/works with fan ON
Yellow is Ground wire

Got DC Voltage at white/yellow
Then check for DC Voltage at RED & Yellow (RED is DC + to gas valve solenoids)




Battery Voltage
Drawing voltage below 12.1V can cause damage
You drawing them down to 10.2.....they ARE Damaged

[garyemunson]

deleted

[RollandBC]

Yes that photo is not mine just 1 the same looking
I will try that