My heater wasn't working in the truck I recently pulled home (after sitting 35 years) so I pulled it out and tested it with the battery and it worked fine. Tried the fan unit connected to the switch in the cab and ground to the frame and it worked. When I slid it into the heater housing however it did not work at all. Went through this cycle a couple of times with the same results. Thinking it's a grounding problem but can't seem to find it... any thoughts?
