Furnace Help

[NY Camper 86]

Kicked on the furnace a month or so ago to make sure all was running well before the cool weather kicked in. Ran like a champ and kicked out good heat. Well now here we are and its cold, kicked on the furnace and its not kicking out that same heat that it was. Any ideas or thoughts on where I should start? I know its getting the propane as the blower outside is kicking out heat. Just need to know where I should start as it is going to be in the 20's here the next few nights and space heaters only heat so much.

Thanks

[okcnewbie]

If you turn the fan switch at the thermostat to on does the blower come on? Are you positive that your batteries are charging. It sounds like you are on shore power but sometimes the converter stops working correctly.

Here are a couple of other things to check that I copied from RVbasics.com.

Fan doesn't run and no heat.

If the fan will not start you should first check that your battery is good and you have 12 volts at the furnace. You could have a tripped circuit breaker or blown fuse.
If the battery is good and you have electricity to the RV's heater next check the thermostat.
Remove cover and look for the "anticipator" adjustment. (Note: Some new thermostats do not have an anticipator.) It will be an adjustable control with a sliding contact over a straight bare wire or a bare wire wound about an insulating material. If the fan will not start set the temperature to maximum and then move the anticipator slider while listening for the fan to start. Be sure to wait long enough... it normally takes our furnace 30 seconds for the fan to start once the thermostat sends a signal.
If the fan starts after you move the slider then you have probably found the problem. In this case you may find a slider position near the original position that will work reliably. If your thermostat anticipator adjustment uses the straight wire design and the wire lies directly on the plastic housing then you should look to see if the wire has sunk into the plastic. This wire produces heat and causes the plastic to melt a little and the wire to sink into the plastic so the slider no longer makes contact. It may be necessary to replace the thermostat.
Fan runs but no heat.

If your furnace fan starts you can assume that the thermostat is working.
Possible problems are insufficient air flow through the furnace a bad propane valve at the furnace or a bad regulator at the propane tank.
A furnace contains an internal sail switch, that senses the air flow. If the air flow is not sufficient then the switch will prevent the furnace from igniting and the fan will run but you will get no heat. A slow motor speed could be caused by a low battery or other low voltage cause such as a bad connection in the wiring.
Low air flow could also be caused by a restriction in the ventilation system. Check to see if any heat registers are closed or blocked. Some furnaces will not tolerate even a partial closure of a heat register. .
If you have an electronic ignition check to see if the two contacts are touching or are too far apart. They should be about 1/8 apart.

[chief02]

Do you have propane, does the stove work. If you recently filled the propane tank and opened it to fast you may have tripped the excess flow valve inside the tank valve. This will prevent the flow of gas. Turn off tank, slowly disconnect the hose, reconnect hose, open slowly, try furnace. But...what do you mean " not kicking out heat like it was". Is it working but just not warm enough or low volume or blows cold?

[NY Camper 86]

The fan does run no problem. Just isn't kicking out as much as it was before. I haven't gotten propane recently. But I could try disconnecting it. The stove works no problem.

[Rook]

Hold our hand near the exterior exhaust of your heater, be careful, it can be very hot and burn you. If it's only luke warm, then it's possible your propane pressure is too low (bad main propane regulator or main valve not fully open). Or, you could have a defective burner solenoid valve. Also you could have a restricted hot air flow inside the coach causing too much back pressure on the furnace blower.. Rook

[shiggs68]

Check your duct work for disconnection or restrictions. As you move your rig, things sometimes work lose.

[NY Camper 86]

The exterior exhaust is kicking out hot! That is why this is all so confusing to me.

[Rook]

Is the airflow inside from your heat vents normal VOLUME? Rook

[NY Camper 86]

No whats coming out of the registers isn't as powerful as it was when I tried it before.

[Rook]

Sounds like you may have a partial blockage in your duct-work somewhere.....Hard to say where. Also, your duct-work is likely metal.....it will absorb most of the heat when the furnace first comes on. The furnace must run a few minutes to give the coach max heat. Rook

[NY Camper 86]

I will have to pull the air ways open when I get home and suck them out with the vacuum and see if that helps. Got to have heat and I am really hoping it is something simple.

[Rook]

The most common air flow blockage is in the cold air return for the furnace. PET HAIR, FUZZ, etc. can block or collect on any grills, grids or rotary fan blades in the path of cold air returns. Rook

[NY Camper 86]

That sounds right up my ally I have two cats and two dogs. Do you know where I might locate the cold air return? Its a travel trailer. And thank you for all your help. I may not have to sleep cold tonight!

[chief02]

Or leaky or disconnected duct.