Does anybody know exactly how a LP gas furnace is supposed to work in a class C motor home?

Question

I am trying to get my furnace to stop blowing cold air

there is no pilot light or is there any place to light the furnace, i put in a new thermostat and someone said that the heat anticipator is out of adjustment

the furnace never blows warm air it is just cold

Answer 1

I seriously doubt that it is the heat anticipator needs adjustment. Most of those units made after the early 80’s are sealed combustion with direct spark or intermittent pilot ignition. Most of them have an ignition sequence that starts the blower motor and the draft induction motor at the same time. This means that the blower motor is running before your main burner is running (blowing cold air). I’m not sure from your question if it starts blowing warm air later, or if it is not blowing warm air at all.

Do you get warm air eventually, or does it just blow cold?

Edit:
Ok, if it never blows warm, you’re going to need some serious trouble shooting. On the intermittent pilot models the most common problem is pilot orifice getting plugged. On these units a small electronic spark igniter lights a pilot light that only runs when there is a call for heat. The pilot orifice gets plugged and the flame sensor will not allow the main burner valve to open. On the direct ignition models, the most common problem is the flame sensor itself. Keep in mind, I said in most common problem; it could in fact be a number of other things. Problem with these units is that they are built so compact that they are a pain in the butt to work on, and for this reason most HVAC techs don’t want to touch them. Parts are very specific as well, so your best bet is to call around to Camper dealerships that have a good tech on the staff (very hard to find). As I said before these are sealed combustion units and you should really not tear into this unless you really know what you are doing.

If you need help finding someone, feel free to email me with your location. I know a few good techs around the country that might be near your location.

Answer 2

You don't say how old this unit is. I worked on one a week ago that was doing the same thing. It had a pilot light which had to be lit, pretty much like the pilot on a gas water heater at home. If there is a front cover on the heater it should be removable and then you'll see the pilot and gas control. Turn gas control to "pilot" position. There is a button which has to be pushed in and held while lighting the pilot. This button has to be held after lighting for 15 to 20 seconds in order to warm up the thermocouple which tells the electronics the pilot is on. If the pilot is working and the burner still won't lite and produce heat then look at the "Sail switch". This is an air vane switch which the fan has to move in order to let gas flow. Just because the fan is blowing air doesn't mean the sail switching is being made. The one I worked on had been stored for a while and had mud dobber nests in the vent and intake which were keeping the fan from getting to full speed to move the switch. I had to remove the heater from the RV to find the restrictions. Low battery voltage will also keep the fan from achieving full speed. A weak battery, bad wiring or a bad ground are causes of low voltage at the heater. Measuring good at the battery doesn't mean much. Check at the heater connections with the fan running.

Good luck

Answer 3

First make sure the gas tank valve is open, 2nd set the thermostat to a high temp, third light the pilot. Wait for element to warm up then the furnace will kick on and blow warm air. Good-luck.

Answer 4

usually those furnaces are electronic. make sure the on off switch on the thermostat is set to on, an set the temperature.
the furnace should start in about 20 seconds. if you like the furnace to stop blowing cold air, set the thermostat switch to off

Answer 5

A, B, C, are body styles, not engines. I have seen gas pushers and diesel pushers. Rarely have I seen the front engine diesel, but am sure they are out there as if it can be done, it will be done.