I have checked the vacuum lines and watched the door open and close that directs the air flow. I have looked at the vacuum reservoir ball and it looks intact. I have unplugged the main vacuum junction behind the glove box to see if the doors fail to function and they do. Could it be the actuator near the airbox? I am stumped as to where to look now. 2001 Ranger XLT

 

when you say partially what do you mean? do you have all 4 blower speeds?

 

I have all blower speeds available but most of the air comes out of the defrost vents. That's what took me down the vacuum leak road. I thought maybe the heat control bypass valve could be the problem where the vacuum line connects but after reading some that seem to control coolant flow

 

The blend door actuator only controls the temperature. It opens/closes the door between the heater and AC to "blend" air for the temp setting. So if by partially blowing do you mean not blowing fully cold air? (blend door issue). Not blowing the air very hard on any fan setting? (fan or switch issue). Stuck only blowing out of certain vents? (vacuum/control issue).

 

Not blowing the air very hard on any fan speed. The air is cold so there is a vacuum issue somewhere. I just can not seem to find any problems with the lines or the vacuum resivoir.

 

Definitely sounds like a vacuum leak making the vents stick in one position. The best advice I have in my arsenal for finding leaks in the HVAC system is to buy a cheap vacuum guage. Start pulling vacuum at the beginning of the system closest to the actual lines from the engine and work your way all the way to the actual vent controls. Might take 2 people, one person to mess with the controls and one person to keep pulling a vacuum as you open and close different parts of the system. You might get lucky right off the bat and find the resivoir is bad (they are known to crack and leak).

 

Defrost is the default vent, so no or low vacuum = Defrost vent

There are only 2 vacuum "motors", yes they call then "motors", that control the vents
There is a 3rd for "Fresh air" usually only used for MAX AC setting, yes, AC only has on or off, MAX AC just closes outside air inlet, so "recools" inside air, for "MAX" cooling

Diagram here of standard system: http://www.explorerforum.com/forums/...iag-gif.41768/
Vents are labelled V(vacuum) and NV(no vacuum) for there positions in that state, and one is PV(partial vacuum)

As said above the Blend Door has nothing to do with Vents, or air speed, it just directs air flow thru the heater core or around the heater core, strictly Temp Related, and either electric or cable operated.

On a 2001 there may also be a 4th vacuum motor, its in the engine bay, it controls a Heater hose valve, it will be a Grey colored vacuum hose(on Rangers), comes out of the firewall with the Black hose that goes to reservoir.
In MAX AC hot coolant flow is stopped by this valve closing, called "water valve" in diagram.

The Black vacuum hose coming out of the firewall is where the problem usually is found, its a hard plastic and it cracks.
But to test just find the end of this black line, or cut it, if you have rubber hose to reconnect it and then suck on the end going into the cab.

Vacuum is not used up for the most part, so if you suck on this black hose it should HOLD vacuum, if its not then get a friend to listen in side while you suck or blow into it, they will hear the air leak.

 

Dealing with this same problem - so thanks for the detail and will follow.

 

'99 B3000 104k mi. I doubled the air flow on my AC by removing blower motor & using an air chuck with a long wand, I BLEW ALL THE CARP blocking the flow btwn. the evap. core fins. *Be careful not to bend over & flatten the aluminum fins!
DON'T USE FOAMING evap./condenser cleaner! Most have a sodium(salt) based solution that eats the aluminum fins & solder.

 

'99 B3000 104k mi. I doubled the air flow on my AC by removing blower motor & using an air chuck with a long wand, I BLEW ALL THE CARP blocking the flow btwn. the evap. core fins. *Be careful not to bend over & flatten the aluminum fins!
DON'T USE FOAMING evap./condenser cleaner! Most have a sodium(salt) based solution that eats the aluminum fins & solder.