Atwood Furnace fan starts, won’t ignite- blows fuse.

Just retired this week and leaving tomorrow for Qratzsite. Went to start the furnace today to warm the camper as we loaded it up. The fan came on as normal, but at about 20 seconds instead of hearing the whoosh of ignition I saw a spark at the wall thermostat and the fan shut off. There was an electrical smell, so I figured the thermostat was toast. I’ve replaced a couple over the last couple years, so I had a spare on hand and went ahead and installed it. This time when I turned it on the thermostat sparked again, but it also blew the 15 amp fuse on the 12 volt panel.

I know a furnace guy and he came out, said he didn’t know anythyabout 12 volt furnaces but he would take a look. After further testing he felt he had narrowed it to the gas valve, that turns on after the initial 20 second purge. My question to all of you experts would be could a faulty gas valve cause both the thermostat to toast and blow the 15 amp fuse? If not, what does this sound like?

I have a borrowed Mr Heater so will go ahead and leave tomorrow as planned, but hope to either fix it myself en route or get it fixed in Q once we arrive. We were planning on taking about a week to get there. Any thoughts on this would be greatly appreciated.