Jeffrey Posted October 8, 2012 Share Posted October 8, 2012 This probably should be obvious but for some reason I'm not "getting it" (may have to do with the fact I just returned tonight from a 2800 mile trek in my toyhome over the course of 7 days and my brain is in the fatigue zone). Anyhow, I purchased this '91 Warrior in the spring and tested the furnace while the rig was hooked up to AC. It worked fabulously at the time but it hasn't been hot out so there hasn't been a need to use it. However, on this trip I found myself in cooler night temps and tried to use it without hooking up to ext. AC. It's the Suburban model furnace and I understood it to be able to run off DC. Anyway, the fan came on but no heat. When I got home and hooked up to external AC tonight, it worked great. Can it be work off DC or is it only when I'm hooked up to external AC? I suspect there isn't enough power to run the furnace fan from my single "home" battery, so the answer probably is obvious and my taxed brain is on overload and unable to make any sense out of the obvious. Great trip though! Quote Link to comment Share on other sites More sharing options...
waiter Posted October 8, 2012 Share Posted October 8, 2012 Sounds like your on the right troubleshooting track. The Furnace and blower runs off 12 volts, I don't know how low the 12 volts can fall before things stop working. When the blower runs, it activates a "sail" switch. This switch tells the furnace controller that the blower is running and the combustion chamber has been purged. Three possibilities; 1) Your coach battery isn't charging very well, so the blower can't run fast enough to activate the sail switch. If you have a voltmeter, you might measure the 12 volts with and without shore power. 2) You may have a partial blockage (bug nests) in the intake or exhaust ducts, and the blower can't get enough air flow to activate the switch. Remove the vent cover outside and vacuum / blow air to see if any bugs nests / blockage 3) The sail switch is sticking or dragging and needs more airflow to activate. Replace the sail switch. John Mc 88 Dolphin 4 Auto Quote Link to comment Share on other sites More sharing options...
Totem Posted October 8, 2012 Share Posted October 8, 2012 ^ what he said. I swapped out my 11.8 volt "fully charged" battery from the stealership i got it from with a new marine grade battery and mine worked perfect. prior to that i had exact same symptoms. Quote Link to comment Share on other sites More sharing options...
Jeffrey Posted October 8, 2012 Author Share Posted October 8, 2012 Thanks waiter and Totem I checked the Home Battery and it showed a charge of 13.38, meaning that wasn't the problem. And I thought the battery was relatively new when I bought the unit. However, the connection cable to the Negative pole was slightly loose. Tightened it, went inside, turned on heat and voila, it works on DC. Again, thanks for your feedback. Quote Link to comment Share on other sites More sharing options...
Bob C Posted October 9, 2012 Share Posted October 9, 2012 As Waiter said, look for bugs in the furnace exhaust. While in Wyoming last month we had a 20 degree night and the furnace didn't want to work. I went outside and looked into the furnace exhaust and it was about 50% obstructed. I cleaned it out with a bent coat hanger and the furnace worked. When I got home, I installed a bug screen on the furnace. Quote Link to comment Share on other sites More sharing options...
DanAatTheCape Posted October 25, 2012 Share Posted October 25, 2012 Check your voltage at the furnace -- mine did not work at all until I Iooked for the ground wire - there is a gang of them in the driver's side rear wheel well & several where broken btw, the sail switch is visible with the grill removed. looking into the blower it is on the left side - if it is not flush against the chamber when the fan is operating tapping on the side can "help" it - I have even reached in and pulled it forward for testing purposes. I have seen the voltage thing too. The house battery goes thru a CB & the relay in the converter - given that your fan is running the cb & converter are probably good. I changed my cb because I getting a lot of voltage drop - got one at napa for about $9 (actually got 2 - replaced CB between starter battery & constant duty solenoid that charges house battery while the engine is running) when I removed the cb it was so corroded i decided to replace. I bought a 3 way ring connector so I could hardwire an 400 watt inverter directly into the house battery - (I run laptop charge cell phone/camera batteries/shaver,etc without having to start generator every time), with a digital voltmeter you can check voltage from the battery to the furnace. That 13+ volts at the battery should be 12.5 unless it has recently (very recently) been charged. some drop is expected as you pass by CB etc. I think that furnace should operate below 12 volts but not by much. You may even find starting the engine will give enough voltage boost to light off - if it does then turn off the engine & see if it stays lit. PS: part numbers on receipt Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.