As stated. Defrost blows strong drivers side weak on passenger side. It’s more of a nuisance than anything else. Might there be a simple fix?
How strong should air be blowing on mid-level vents? It appears the middle actuator is working. It moves air from floor to defrost but the air coming out of the 2 vents right above the radio has minimal air.
I don’t recall how it was in previous years/winters. I get plenty of heat. I just don’t feel it very strong.

 

Blend actuator for passenger side.

 

overtime the ductwork gets loose and dislodged, warps, and the gasket material falls apart. This leaves big gaps which leak air. the actuator might be getting tired and just not opening all the way too.

 

Which actuator are you suggesting? I can switch from cold air to hot, so it’s not the blend door actuator. The middle one does work. It moves air from the floor to defrost, except defrost is stronger on the drivers side.
I am “assuming “ the fresh air actuator works because it’s blowing air and heat through the vents. If it were not, wouldn’t there be no air in defrost or the floor?
Iam assuming something might be wrong with the ducts that affect how we’ll defrost works. How does one access the ducts?

 

the one that switches vents. I'm saying maybe it moves, but doesn't open all the way.


take apart the dash. Not fun.

 

It works.,.,...

 

I’d suspect an external restriction of the evaporator and/or heater core, meaning the fins are full of debris and dirt. This causes air to divert in directions it normally wouldn’t and can sometimes cause the air flow to fight against itself as it tries to exit the HVAC housing and ductwork.

The late 80’s was right around a time of transition for HVAC systems - your truck may or may not have an access panel to inspect/clean/change the heater core. If it does, it’ll be on the bottom of the housing on the passenger side.

The evaporator can be inspected/cleaned by removing the blower motor.

 

The heater core is spotless. Both the core and evap cooler are housed in a clamshell box under the dash. I separated it out of curiosity a few months ago and I was surprised how clean it was. The box containing the core does not have direct access to outside air.

 

I thought as much. I won’t do that just to get the defrost to work better. Thanks

 

When the mode is set to full defrost, can you feel air coming out of the panel or floor vents on the passenger side? Note that a small amount of airflow out of the other vents is not uncommon on older vehicles - compare to the driver side to determine if it’s excessive.

If yes, some kind of restriction in the HVAC housing and/or ductwork is the likely cause and removing it for inspection/repair is necessary.

If no, it’s likely that MMJ’s suggestion of warped/loose ductwork is the cause. You might be able to identify/resolve the cause by pulling the glovebox and radio for inspection.