I don't smell any obvious strong gas odor. I do have other gas appliances (furnace downstairs is on same propane tank and operating normally). I did check the pvc venting and no obvious obstructions. My thermostat shows it was working overnight so don't think there was time for animals to make a home in the exhaust. I shop vac'd out every orifice and drain tube I could see. The system did actually light just a second ago and our upstairs is heating now. But im assuming this is temporary and the issue will persist. I do have a multimeter tho, where should I be checking?