1989, 245
153,000

Our drivers side windshield fogs up inside (but not the passenger's side), when the defroster is first turned on and set to the warm position, and I also noticed a burst of smoke, or mist, or dust (?). After the initial fogging up I turn the defrost off, drive a bit further and then put it back on and it works fine, and no cloud of whatever it is.

I removed the dash panels and the vacuum controls, and all the actuators, and the lower recirc door flap appears to be working ok. I did not see any leaks anywhere and the blower is working ok.

Could a leaky heater core cause a drivers side only fogging? ... and could a heater core leak only sometimes?

I notice that leaves work there way into the cowling/air vents in front of the windshield. I tried to blow out and vac out leaves/debris from the outside cowling and inner rocker panel area ducting (as suggested by Volvo owners), but I did not see any leaves or debris come out. Where did that stuff go? Could it be blocking up the system and causing moisture?

The whole under the dash area is so crowded with wiring, vents, relays, connectors, that it is hard to see just how the system works, or where I need to look, and worst of all how to ever get it back together, if one attempts a repair, if needed. How does the water that enters the cowling get separated from the air? But the hardest thing is trying to get an accurate description of the path the air takes after it disappears in the front windshield cowling. What is the route of the air starting at the outside grill vents? What is behind all that duct work and in what logical order? Anyone have a schematic or a way of explaining it in an understandable way?


diyer