my blower motor is working fine and works just fine on the floor and vents. however, the defrost is very weak. the passenger side i would say is working at 40-50% while the driver side is working at 10%.

where do i start looking for the issue?

 

vacuum controlled actuator flaps in the air plumbing behind the dash. the passenger side is accessible by removing the glovebox, but the central and driver side is buried

 

Start off looking at the firewall on the passenger side under hood. You will see a vacuum hose that runs to the top of the engine. On mine that hose was split and not fully attached. That is what supplies the vacuum to that tank and plumbing that Pierce is talking about. On mine that still did not fix the defrost issue(I suspect the tank or hoses from the tank are bad. I ended up disconnecting the vent flaps that attached to the vacuum actuators and set the flaps so that the defrost worked and then taped them up so that they did not close.

It is a temp fix until the weather gets warmer to trouble shoot but until then I want to be able to drive the car and see out the window

Good luck

 

the fact that SOME of his under-dash air flappers are working at least partially suggests to me that its more likely a problem under the dash, and not with the feed. there's also an important one-way valve in there, and I think a vacuum 'storage' thing that looks like 4 black plastic bubbles in a row.

the vacuum line that goes through the firewall ends up at the ventilation control panel, and from there there are various vacuum lines to the assorted flap actuators that direct the air. there's one actuator for the recirculate vs fresh air flapper, another for the defroster vents, and one on each side for the floor heater vents.

 

thanks for the help as always!

where would i find the one for the central and drivers side? im thinking of doing what journey said and force them to stay open, at least for the time being. unless once i get to them they would be just as easy to replace?

 

crisis averted.

it ended up being the vacuum hose under the hood going through the fire wall. got a new length of hose and a connector and now the defrost and floor are at full power.

thanks!