I have a 1988 Toyota pickup I've had for about 2 years now slowly repairing the neglected parts of the truck and I just finished cleaning the evaporator core in the truck hoping it would fix my driver side vents barely blowing any air. The passenger side blows nice and hard but the driver's side barely blows at all even with the passenger side vents closed. I've checked for blockages in the vents but I just can't seem to figure anything out

 

Check the ducting between the air box and the vent. There might be a clog, or someone loosened the duct, or someone removed the duct all together.

Both the driver's and passenger's side vents should blow nicely no matter what the "vent selector lever" (i.e. vent, vent/floor, floor, defrost, etc.) position is.

 

Is it blowing out at the small vent aka "balls cooler" below the steering wheel? That piece of the duct comes from air box and routes back up to the driver's side vent. That piece may have came loose. Removing the lower panel to check that duct piece is pretty easy.

 

If you have this I agree to check, my 91 it was optional but if it’s disconnected most of the air would be going under the dash.

 

It blows pretty good out of the vent below the steering wheel I'll take the dash back out here in a little bit and double check all the vents just to make sure

 

Pull the lower panel off where that vent is, I bet the problem is with that small piece of duct where it slides into the duct that leads to the vent that's not blowing.

 

After tearing the whole dash and half the vents out there is nothing blocking anything but there's a little piece of plastic that I'm guessing is supposed to redirect air in the middle vents circled in the picture I cut that off and now everything seems to be flowing a lot better

 

Also is there any sort of way to add basically a cabin filter to the interior recirculation vent because I don't want to go through the 3 hours of work to get the dash apart for cleaning that evap core again lol