Ok I know this has been covered many times but I'm a newbie ranger owner...I have a 98 ford ranger super cab xlt 4x4 off-road and when I turn on the a.c. it only blows through the defrost but when I switch the **** to 4 wheel high and I hear the hubs lock in then the defroster switches to the vents then I switch off the 4wd and after about a min or two then it switches back to def anybody Have any ideas
thAnk you

 

Welcome to the forum

Vacuum reservoir system has a leak and I bet its the PVH(pulse vacuum hubs) system

1998 to 2000 4x4 Rangers used PVH, most have converted these to manual hubs, just FYI.

Look here at diagram of the system: https://www.justanswer.com/car/0k2ac...ging-cold.html

To HVAC in the diagram is for cab climate control
Cab vents are all run by vacuum valves
No vacuum = Defrost vent, its the default setting

If the PVH solenoid's Valve has a leak when closed, i.e. in 2WD, then you would lose vacuum in the reservoir, so cab vents would not work.
When you select 4WD the PVH solenoids valve opens so no more leak, and hubs can engage.

Locate the PVH solenoid, usually under the air cleaner box.
Locate the two vacuum hoses
Pull off the hose that goes to Vacuum reservoir, big round black plastic ball, and plug that hose.
Start engine
See if vent controls work now

If so you will need a new PVH solenoid, but..............I think you should look at getting AVM/Rugged Ridge manual hubs instead
The PVH system was never very reliable so investing money in repairing it wouldn't be a good use of that money, in my opinion


It is possible the last person that worked in the vehicle reversed these two vacuum lines, not sure that it would matter but...............try reversing them and see if cab vent function returns in 2WD

 

Ok I plugged the one hose used the airbox and air is blowing through my vents what happens if I leave it plugged and unhooked so I have a c

 

Under the airbox...typo sorry

 

You will lose 4WD because front hubs will not have vacuum, but other than that nothing else.
But you can always plug hose back in when you want 4WD, because vents stay working in 4WD

 

Thank you for the help