Just picked up thread. Lmfao!!! #1. Highest thermostat you can get 180dgr. if possible. At -30c put card board in front of rad,cutout a couple of holes. My bj has a rear heater. Had exactly same prob with blend door makes decent heat. As is newly turboed with intercooler in front of rad I'm not running a winter cover. What do you get when you turn on heater fan in a cruiser? Answer. WIND CHILL ha ha