Tank switch position, heater won't run

oldtool2 · 01-08-2016, 10:44 AM

The temperatures finially got cold, 8 to 15 degrees this past week. My electric heater couldn't keep up so the furnace was running. Went out to check the trailer yesterday and found it was 31 degrees outside, 66 inside, so checked the furnace and it wouldn't run, so checked the propane and of course found the tanks empty. That didn't surprise me, shpuld have been keeping an eye on them. After all, I do have guages on the tanks. No big deal, pull them and go get them filled.

Put the full tanks in but the furnace won't fire up. I lit the range and all three burners lit right up with no delay. This told me there was gas in the line but let them run for a couple of minutes to be sure. Shut the furnace off and turned the thermostat all the way down. Faited 5 minutes or so and turned the stat up and the heat switch back on. Still nothing. I mean nothing, can't hear the ignitor firing or anything else happening. Of course the fan is not running either. Flipped the stat switches back and forth a few times in case there was any corrosion on them but again, nothing! Checked to be sure we turned the tanks on, I did, Changed the selector switch to select the tank on the passenger side to open first. This is the tank I normally work from first.

I remember reading somewhere you need to change this otherwise you will be connected to the tank that went empty last. I wanted to be connected to the tank that went empty first, the passenger side tank. Lets call this tank number one.

So first question. Did I need to change that switch or could I have left it the way it was? This switch rotates 180 degrees, from west to east if that makes any sense. The west position appears to be the closest tank (passenger side) and east position is hooked up to the other hose (drivers side tank).

Second question, shouldnt I hear the blower (fan)running? I tried to get it to run in the AC position but I think it is too cold in the trailer for it to come on. Then again, the fan should run even with the AC/heat switch in the off position. It won't run no matter what. It is 34 outside and 69 inside so the furnace should be running.

This is an old analog type thermostat. Fan switches high / low, on /auto, AC / off/ heat positions.

Jim

**Bama Rambler** · 01-08-2016, 10:50 AM

Have you removed the fuse for the furnace and replaced it. Once the furnace fails to fire three times it locks itself out and you have to cycle power to reset it.

I'd try that first if you haven't.

youroo · 01-08-2016, 10:56 AM

You said the Stove Top is working so you can forget about the Propane Issue! Check your 12V fuses on your Furnace!

Youroo!!

oldtool2 · 01-08-2016, 11:42 AM

I knew I forgot to mention something. I checked for power on the thermostat. I have 7.7 VDC at one terminal and 13.0 VDC (on shore power right now) on two thermostat terminals.

Is there a fuse located at the furnace itself? Possible I guess but didn't see it when I checked the furnace wiring. Will have to look again.

Jim

oldtool2 · 01-08-2016, 11:48 AM

Quote:

Originally Posted by Bama Rambler

Have you removed the fuse for the furnace and replaced it. Once the furnace fails to fire three times it locks itself out and you have to cycle power to reset it.

I'd try that first if you haven't.

I know after three tries you need to do a reset. Shutting off at the thermostat for a few minutes and then turning back on will do that.

My problem is no power for the fan. If fan doesn't run the spark won't fire so burner won't light. Doing a reset won't help if the fan doesn't run.

Jim

TimVWulp · 01-08-2016, 11:50 AM

Hi you need to reset the furnace safety's. Turn the heat setting off on the thermostat. Now turn the heat switch back on. This will reset the electronic control module board safety's. The furnace should try to restart and clear the air from the gas line. It will try 3 times to start the burner and will lock out again if it dose not clear the air from the gas line to lite the furnace burner. It may take several try's of turning off the heat at the thermostat to clear the air out of the gas line to get furnace to lite.

Hope This Helps Tim

TimVWulp · 01-08-2016, 11:59 AM

Quote:

Originally Posted by oldtool2

I know after three tries you need to do a reset. Shutting off at the thermostat for a few minutes and then turning back on will do that.

My problem is no power for the fan. If fan doesn't run the spark won't fire so burner won't light. Doing a reset won't help if the fan doesn't run.

Jim

Hi control board module has let some smoke out and will need to be replaced.

Or you mentioned that you had only 7 vdc on one wire. Is this the white wire on the w terminal of the thermostat? This needs to have minimum of 9.5 volts dc to the control module board for it to operate. If this is true furnace will not start. Jump power from R to W at thermostat if furnace starts t stat has failed.

Hope This Helps Tim

fonzie · 01-08-2016, 02:00 PM

Here thread with similar issue......

http://www.forestriverforums.com/for...0ws-48828.html

oldtool2 · 01-09-2016, 01:18 PM

Quote:

Originally Posted by TimVWulp

Hi control board module has let some smoke out and will need to be replaced.

Or you mentioned that you had only 7 vdc on one wire. Is this the white wire on the w terminal of the thermostat? This needs to have minimum of 9.5 volts dc to the control module board for it to operate. If this is true furnace will not start. Jump power from R to W at thermostat if furnace starts t stat has failed.

Hope This Helps Tim

Can I ask what you are smoking? No one mentioned any smoke anywhere.

As for the voltage, it is right. It is the red wire and connected to the terminal marked +7.5 on the stat so it is right.

Jim

**Flybob** · 01-09-2016, 01:29 PM

I assume you are plugged in as you were running electric heat. You say you have less than 12V on the furnace power then that is your problem. The furnace and fridge have a safety feature that will not allow them to run if the 12V source is too low. Check your converter, the high current battery protection fuses and the battery. What is the voltage at the battery terminals. Is it possible there was a power surge/failure when you were away and a fuse blew.

TimVWulp · 01-09-2016, 03:44 PM

Quote:

Originally Posted by oldtool2

Can I ask what you are smoking? No one mentioned any smoke anywhere.

As for the voltage, it is right. It is the red wire and connected to the terminal marked +7.5 on the stat so it is right.

Jim

Hi it is a term used by electronic control technicians when a circuit board fails. When the board fails the component on the board that failed will let some smoke out when it burns out or fails.

So my next ? is The red wire which is on the R terminal powers the thermostat. The voltage from R to W G Y terminals with the thermostat in the off position should be 12 volts. If it is less than 9.5 volts the control board on the furnace is engineered to not let the furnace start.
Is the unit plugged into 110 volt shore power or house power. The furnace is a real power hog and will kill a battery very fast.
My assumption is that it is as you stated that the electric heater could not keep the unit warm so it is plugged in. Is your battery low on water or an older battery and failing?

Hope This Helps Tim

oldtool2 · 01-10-2016, 02:22 PM

Quote:

Originally Posted by Flybob

I assume you are plugged in as you were running electric heat. You say you have less than 12V on the furnace power then that is your problem. The furnace and fridge have a safety feature that will not allow them to run if the 12V source is too low. Check your converter, the high current battery protection fuses and the battery. What is the voltage at the battery terminals. Is it possible there was a power surge/failure when you were away and a fuse blew.

Bob,

As stated I have a terminal marked +7.5 VDC and it has 7.5 to 8.0 VDC on it. I had considered changing this old analog stat once and this is the voltage it had then and the heater worked right, with no problems. The AC also worked as it should.

My thermostat has six terminals. They are marked as follows from left to right. +7.5, cool, fur, hi, hi, fan, grn. Reading voltage from the terminal to the grn terminal (this is the negative battery terminal) I read +7.5 VDC, +7.5, 13, 13, 13, negative (ground). This is with it connected to shore power and the cool / heat switch set to off.

Jim

oldtool2 · 02-23-2016, 11:21 AM

I just realized I left everyone hanging on this problem. After driving myself crazy I decided to replace the stat. Guess what, it was a bad thermostat! After getting everything working right I checked the old stat and found a bad, broken, solder joint from the terminal to the board. Sometimes it would make, other times it would not. My 70 pound dog running inside would cause enough vibration to cause it to work or not. The new stat is working great!

Thanks everyone for trying to help, I appreciate it!

Jim

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