Air dryer safety valve popping off when cold

I think I figured out the problem. I just crawled under the truck, and I'm getting 13v at the connector to the heater plug, but when I check the heater leads for resistance, my meter doesn't budge. So I'm off to fleetpride to get a new heater and ring clip pliers, change it out at the Petro parking lot and will report back.

 

Swapped the heater no change. I haven't replaced the heater yet because my financial situation isn't the best this month. No, I don't take cheap freight either. If I can find one for a more affordable price than the dealer, I might do it this weekend when I'm on the west coast in much warmer temps.