Defrost/Vent / vacuum issues?

[dangeranger88]

I'm having this issue with my 1999 Ranger XLT with the 3.0 -- When I am going up a hill at 3000RPM or higher, the vents will start blowing through the defrost. Its very annoying! Does anyone have any ideas about this? I assume its some sort of vacuum issue...I also know that this model had vacuum-operated auto hubs which I replaced with manual lockouts, would that maybe have anything to do with it, even though i did that almost two years ago and this issue only recently started happening.

Also, I'm not sure if this is related or not but while idle, the AC compressor clicks on and off in a rhythmic fashion. Bothers me a bit. AC works great however. Any suggestions? Thanks guys

Oh and if it may help the ranger's got 33" tires and 4.10 gears in the rear.

 

[Big Jim M]

Yep!

I'm having this issue with my 1999 Ranger XLT with the 3.0 -- When I am going up a hill at 3000RPM or higher, the vents will start blowing through the defrost. Its very annoying! Does anyone have any ideas about this? I assume its some sort of vacuum issue...I also know that this model had vacuum-operated auto hubs which I replaced with manual lockouts, would that maybe have anything to do with it, even though i did that almost two years ago and this issue only recently started happening.

Also, I'm not sure if this is related or not but while idle, the AC compressor clicks on and off in a rhythmic fashion. Bothers me a bit. AC works great however. Any suggestions? Thanks guys

Oh and if it may help the ranger's got 33" tires and 4.10 gears in the rear.

Sounds like when you disconnected the vac operated hubs you encouraged a vac leak..
There is a cannister that KEEPS vac in it to make sure the hubs and the A/C doors have vac when the engine isn't providing it..
So I'd be taking a good look at the canister and all vac lines.
The FAIL-SAFE of the heater/AC is to go to defrost when vac failure occurs.
Big JIm

 

[hondaxr650]

You probably have a vacuum leak. The heater defaults to defrost when vacuum is lost to the controls. Lots of folks have found their vacuum reservoirs cracked. It looks like a black ball and is down in the rf corner of the engine compartment.

Looks like Big Jim beat me to it!

 

[dangeranger88]

Okay thanks guys, that is very helpful I will check things out. Where can I look for the vac lines that go to the hubs? I don't remember ever seeing them! Maybe I can just plug them up?

 

[triumphrider-1]

The vacuum lines attach to a metal line on the top of the spindle. If you've put manual hubs on, just pop the lines off and plug them up at the T (located near passenger frame rail and front cross member).

--OOPS. Knuckle, not spindle.