mountainmansteve Posted March 22, 2013 Share Posted March 22, 2013 The furnace in my 1986 Class C Dolphin stopped firing. The blower comes on when heat is called for, but the burner doesn't fire. I pulled the igniter and set the thermostat to call for heat, but I didn't see the igniter fire. Perhaps it doesn't work this way, but that is what I tried. When the furnace was working there was a ( less than 30 second) delay between the blower starting and the burner firing. Can anyone please give me some insight or a link to a troubleshooting/repair guide.? The information on a tag on this unit says: Terralab Engineering S/N 1215014 Gas Fired Heating Unit Thanks. Quote Link to comment Share on other sites More sharing options...
Derek up North Posted March 22, 2013 Share Posted March 22, 2013 Terralab is a new name to me. A bit of Googling indicates that they might have become Atwood. Atwood makes a Model 7916, which MIGHT be what you have. Here's the manual:- http://bryantrv.com/docs2/docs/hflameservice.pdf Quote Link to comment Share on other sites More sharing options...
zero Posted March 22, 2013 Share Posted March 22, 2013 I assume it's an Atwood Hydroflame furnace? As I recall, Terralab had their name on them but did not design or build them. You said you "pulled the ignitor." Is this a pilot light model with piezo ignitor, or a model with an electric automatic ignitor? Makes a big difference in diagnosing problems. Quote Link to comment Share on other sites More sharing options...
waiter Posted March 22, 2013 Share Posted March 22, 2013 Sail switch is the number one problem. The blower may not be running fast enough to toggle the sail switch. Does it fire up OK when your plugged into shore power or if the truck is running. if so, thats a sure sign of the sail switch. It measures airflow in the blower to verify that the blower is running and a successfull combustion chamber purge cycle has taken place. For testing purposes, you can use a jumper around the sail switch. DO NOT operate the furnace without the sail switch. its there to verify the blower is running. John Mc 88 Dolphin 4 Auto Quote Link to comment Share on other sites More sharing options...
mountainmansteve Posted March 23, 2013 Author Share Posted March 23, 2013 Wow! Thanks for welcome and the timely reply with suggestions and manual. I am not sure what the sail switch is or where it is located. However, I just tapped the valve body (several times)where the gas supply goes to the unit and like magic, the burner fired. I turned down the thermostat and the unit turned off. I turned the up the thermostat and the blower started in <10 seconds and the burner fired in ~15 seconds. I have repeated this twice. I also got some more information off of the front panel that I didn't see earlier; might even be important Model Number FA 7816 Model Suffix D Hydro Flame Corporation, Salt Lake City, UT 84104 Thanks, again, for your help. Nice to be warm! Quote Link to comment Share on other sites More sharing options...
Derek up North Posted March 23, 2013 Share Posted March 23, 2013 Hard to guess what the difference is between a 7800 Series and 7900 Series. I'm assuming the '16' indicates 16000Btuh. But glad to hear you're not freezing. Quote Link to comment Share on other sites More sharing options...
mountainmansteve Posted March 23, 2013 Author Share Posted March 23, 2013 Thanks, again for the outstanding information and support. I looked, again, at the panel. It could be model 7916, I'm looking for a magnifying glass to be certain. Truly, Steve Quote Link to comment Share on other sites More sharing options...
Derek up North Posted March 23, 2013 Share Posted March 23, 2013 It's probably 7916. The only reference to the 7816 is your post on RV.NET! Quote Link to comment Share on other sites More sharing options...
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