Hello. Just joined the forum. I have an issue with my 88 HiLo Fun Chacer. I turn on the furnace via the thermostat and the furnace ignites and runs for quite a while then it just blows cold air. Any tips on how to fix this? New thermostat maybe, or ignitor? Also the fan makes a squealing noise. Should I spray it with ? to stop the squealing? Thanks everyone. We are staying above 10ft right now so any help with this is much appreciated.

PotStirrer,
The furnace blower motor in my 1988 22ft Funchaser was squealing badly. I had to remove the furnace completed from the HiLo and replaced the furnace blower motor. If I remember correctly, there is more than one type on blower motor. Specifically, for my unit I needed a "Suburban 520950 Old Motor" that I purchased for around $95 on Amazon (However, I just checked and they are currently not available on Amazon at the same link. The replacement motor came with high level instructions on how to remove and install the new motor which was helpful! https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

The furnace model number will be located on the data plate and will begin with "NT", "GT" or "DD". The serial number will have nine digits. NOTE: Furnaces manufactured prior to 1990 will not have a nine digit serial number

From https://www.google.com/search?q=subu...hrome&ie=UTF-8

I'm guessing but if your furnace is igniting correctly and running for some time as you indicate before blowing cold air it may be due to lack of sufficient air flow or high temp which actuates the gas shut off valve. See explanation below on how a furnace works and some trouble shooting tips. Hope this helps!

Peter
**********************************
How A Furnace Works:
- A thermostat summons heat via a circuit board inside the furnace.
- After a short delay, the board activates a dual-purpose blower, injecting air into the combustion chamber while also moving air thru the ducts.
- A sail switch closes, signaling that the blower has enough air for combustion to occur.
- A gas valve is opened, admitting gas into the burner inside the combustion chamber, where an electrode assembly produces spark.
- Combustion occurs and gasses are vented outside.
- A limit switch halts gas flow if temperature is too high or if the blower becomes
inoperative.
- The thermostat controls furnace run time.

Troubleshooting Malfunctions:
The most common malfunctions are generally related to one of two items:
- DC voltage and/or gas pressure.
- If the fuse panel is ok, use a 12v DC tester to check for power in the wires leading into the furnace. This will ensure that you have an uninterrupted power circuit.
- Check voltage to make sure it is adequate - at least 11 volts. Compare voltage at the battery and at the furnace. In weak circuits, voltage may drop as much as 1 volt between the battery and furnace, suggesting larger wiring is needed or battery is not capable of holding a charge.
- If the voltage is good, the problem may relate to the furnace circuit board, a relay, faulty blower motor, or another component such as the thermostat.

I recently ran across this article and thought I would pass the info on. Hope it helps you out.

Bob
__________________
2014 FR Heritage Glen 282RK
2013 F250 HD 6.7L Diesel
Formerly Owned: 1995 22D Fun Chaser & 2901L Classic

PotStirrer, I just remembered that I have a photo for the Furnace fan replacement procedures. See attached.

Peter

Attached Images

NT16S Motor Replacement.jpg (182.4 KB, 19 views)

Thank you so much

My 85 fun chaser squeals like hell upon start up then quiets down during the run cycle when warm. Then after reaching thermostat level it shuts down the burner but continues to blow during the cool down cycle like normal. But during this phase the squeal returns. I would guess I need the same motor Suburban 520950 Old Motor. I wonder if a competent motor repair shop can rebuild it? Most likely have to buy a new double ducted unit.

The issue I had with my 1509 was two exhaust ducts going from the furnace to the opposite end of the camper. This caused too much resistance so we shortened one so it vented below the table/bed. Still, the heater was not intended to warm my camper above 55 degrees so I used a Little Buddy part time ( not all night) for greater comfort.