Defroster Issue

Hello all. So for the past few months my defroster has been having an ongoing issue, where it allows my driver side window to fog up constantly. It keeps the windshield and passenger-side window nice and clear, but I have to constantly wipe my driver side window with a towel to be able to see out of it. Its as if the left-most (if you're looking forward at the windshield from the driver's seat) defroster vent isn't emitting very much airflow (yet the left side of the windshield seems unaffected oddly enough. Any ideas on how to address this, as it's immensely annoying? I've considered getting an air nozzle on my air compressor and blowing out that vent, but wondered if blowing whatever may be in there deeper into the vent could create more problems than solutions. Has anyone experienced anything similar? Any help will be much appreciated. Thanks

 

You might have something in the vent? Try something like a weed blower on the interior side first. Open the hood and see if anything blows out? Maybe you have leaves or a critter nest in there?

 

Is there air flow with the A/C on? Maybe the hose is off to that side?

 

I will check that out after work today and report back. The truck is garaged 95% of the time, and is my DD, so I'm fairly doubtful of critters, but leaves aren't out of the question I suppose. I'm leaning more towards 20+ years of AZ dust being packed in there. My main concern is whether or not blowing that dust inward, from the cab towards wherever those vents lead, could damage or block other parts of the AC/heat ducting system. I might look at my Factory Service manual at the schematic breakdown of that system before committing to blowing whatever is in there back that way. Any idea whether or not I can actually break into that system from the engine bay side and blow out into my cab? It'd probably make a royal mess in there, but I could always vacuum that out afterwards. Was hoping to get some info from anyone else who'd experienced similar issues.

 

The driver side AC vent (left of the steering wheel) does get airflow with the AC on, but I've never really put my hand over the dash to feel for cold air coming out of the upper dash/defroster vents. I'll check this out this afternoon too.

 

The vents don't go through to the engine bay at all. They "start" in the cowl below the windshield, go into the blower motor, and then out into the cab behind the dash, and under the seats (alongside the transmission hump).

If the truck has been in the garage most of it's life, I would more likely suspect that one of the ducts has disconnected behind the dash.

 

I will definitely try to investigate that. If I remove the lower dash panel below the steering column, do you think I'll be able to see up there far enough to determine if that's the case? I'd like to not have to go too far into a dash removal to diagnose this issue if I don't have too. Despite this truck being garaged, it does still get used as a hunting & camping rig, and up here in Northern AZ we do get some heavy dust that could be blocking that vent too. You think the disconnected duct is a more likely culprit though? I figured since these trucks don't have cabin air filters the dust accumulation could be pretty serious up in there

 

That removing the lower dash panel should allow you to see just fine!!

Duct work tends to come apart.

Rodents also like building nests as well.

 

I think just getting it opened up from the blower motor and giving things a clean out will lead you to whatever the issue may be.