I’ve replaced the Blend Door Actuator on my 2009 Ranger but now need to replace the Mode Door Actuator as I can’t get air flow to change from the defrost vents to the front panel vents. Not sure where the Mode Door Actuator is located and hope it doesn’t involve dropping the dash. Thanks in advance. -Tom

 

Welcome to the forum

The TEMP control **** runs the Blend Door, sends air from the fan thru heater core(HOT) or around it(COLD)

The Vent controls/doors are Vacuum operated, Defrost is the Default, no vacuum needed
Panel or floor require vacuum at the back of the climate control panel
Good news is that its a common issue with a common place to look for the problem

The engine is, of course, the source of the Vacuum for the cab vents
But it has a Vacuum reservoir that holds vacuum at a stable level, much like Power Brakes have the large vacuum reservoir, called the booster, that holds vacuum even after engine is off

So the Cab's Vacuum reservoir is a black plastic ball on passenger side at the front of the vehicle down low, its in front of passenger wheel in front of the wheel well
You need to know where it is to find its TWO black vacuum hoses
These are the hard plastic vacuum lines so "look like" wires
One hose comes from the engine of course, its possible but not likely this hose is bad, but you would have a high idle, which you don't mention

The other hose is the one you want to check, it runs along the top of passenger side frame to the firewall in engine bay
It often gets melted by hot exhaust manifold or pipe, or gets brittle from the heat and breaks, easy to repair with rubber vacuum hose of the right size, just splice it, no clamps needed its a vacuum line

Easiest way to find it is to look at the heater hoses and find the Heater Bypass Valve on the heater hoses, bypass valve will have a GREY vacuum hose
Follow that grey hose down to the firewall, it goes in next to/with the black hose and into the cab
Once you found that end of the black hose follow it in the engine bay to the reservoir "ball" and look for the break
95% of the time its this black hose that's damaged
4% would be a cracked Reservoir, especially if this vehicle was ever in a front end collision
1% would be disconnected engine vacuum hose, or vacuum issue inside the cab


HVAC Mode Door Actuator would be the actual Climate control **** on the panel, very unlikely for this to be the issue unless it has been physically damaged, i.e. hit with a hammer

 

Hey RonD,

If I'm getting a small amount of cold air out of the floor vents when I have AC or Max AC on would that be a vacuum leak in the lines behind the dash or the actual mode door actuator would you think?