Blend door question

[Stainless10FP]

Does the blend door also direct the air flow from the defrost to the front vents or is it’s sole purpose to adjust the temp? Thanks. 2003 Ranger 4.0

 

[Denisefwd93]

I think no, because that is vacuum controlled on the older Rangers I don't know which one you have the blend door is cable controlled the newer use electric mechanical control.

Does the blend door also direct the air flow from the defrost to the front vents or is it’s sole purpose to adjust the temp? Thanks.

 

[RonD]

Blend door just directs flow thru heater core(HOT) or closes it off(COLD)

FAN======Blend Door=======Vents

1995 and up Rangers use an Electric Blend Door, 1994 and earlier were cable operated

1994-2012 Ranger use Vacuum Vent controls, Defrost is Default, so no or low vacuum would direct air to Defrost vent.

In the engine bay is a Vacuum reservoir, a black ball, its sole purpose is to maintain vacuum for the Vent Control system in the cab, so if air flow switches to Defrost when accelerating(low engine vacuum) then vacuum reservoir may be the problem.
If no Vent control then vacuum line from Reservoir to cab is broken

 

[Denisefwd93]

You are amazing with your knowledge base Ron!

The blend door on the older Rangers is really low tech, something equivalent to lawn mower or bicycle cable lol

 

[Stainless10FP]

Thanks for the great information Ron. I have visually inspected the vacuum ball and the vacuum line and they look fine. However, after reading your reply and seeing how inexpensive the vacuum ball is, I ordered one and will replace it tomorrow.

 

[Denisefwd93]

There's probably two dozen or more connections under the hood and that eighth inch plastic tubing breaks in a heartbeat because it gets so brittle with age so you may want to start looking for vacuum leaks