Driving my truck the a/c vents to the face and feet just stopped blowing and switched to the defroster windshield vents instead now when I turn heat or cold in any settings or fan speeds it only blows out the defrost vents any ideas as to what happened would be greatly appreciated

 

You lost vacuum.

 

Is this a diesel truck?

 

Commas, periods, and other punctuation devices are available for free right there on your keyboard. Advice on grammar and syntax will cost extra.

 

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And please, the octothorp is appropriate ONLY when referring to units of weight in the English system.

 

Yes, this is a diesel

 

Turn the key to on (engine off). Open the hood and stand beside the front passenger side tire. Have someone switch the climate control vent **** back and forth between the settings (floor, defrost). Observe and report;



Does the vacuum pump kick on?


Does the vacuum pump kick off shortly after you stop switching the ****?

 

No vacuum pump kicks on. the a/c compressor engages and releases. And there is a noise on the top of the block, that sounds like air going thru a pin hole under vacuum but I can't see any obvious issue and it stops within a few seconds

 

OK we are getting somewhere. Do you know where the vacuum pump is?

 

Unless I'm mistaken isn't it on the passenger side fender right by the starter solinoid? I also have a little update. I tried wiggling the vacuum lines (lines run towards the drivers side) at the sensor, or valve (not surewhat it is) that's on top dead center on the engine at the fire wall. Now I'm getting some air coming thru the face vents but maybe 5% of what it should be, and the rest is still going thru the defroster vents. I'm thinking maybe a vacuum leak or the part the hoses go to on the fire wall is bad?

 

It could be a vacuum leak or obstruction, but you should be able to make your vacuum pump cycle on. Bottom line, the most likely culprit is in the vacuum system. Do you have auto hubs / ESOF?

 

Yes I have auto hubs. They were not hooked up when I got the truck but I put new lines and fittings on they are now but unless I manually lock the hubs the 4x4 dosent actually engage

 

If your vacuum pump does not come on, NOTHING that requires vacuum will work.

Go check the SOURCE first.

 

If you've had a vacuum leak for awhile then you might have burned up the pump. Check the fuse (owner's manual has the list) to see if it's blown first. If you fire up the truck and the vacuum pump doesn't come on to bring the vacuum up then you've had the leak so long that the pump most likely has died from running constantly (the pump isn't designed for continuous use, although for the price it costs you would think it was more durable). I did that my last go round ("I'll look at it tomorrow") and ended up buying a new pump (not an inexpensive proposition).


When you get your pump working again (or a new one) you can half split your leak. Unplug your vacuum lines to the ESOF solenoid (passenger side of engine compartment mounted to the fender above the tire - near the vacuum reservoir). Plug the end of the line with your thumb, set the ventilation to anything but defrost (dash only is an easy check) and start the truck (you will need an assistant for this). Wait until for 30 seconds or so (or until the pump stops) and check your ventilation to see if it's blowing as set or through the defrost. If it's blowing correctly the leak is in your ESOF system (somewhere from the solenoid all the way to the hubs). If it's still blowing defrost then it's in the ventilation lines controlling air flow.


I've only had vacuum leaks in the ESOF system (solenoid once and hubs 3 times). I gave up, capped them, and have Warn Premium manual hubs sitting in the garage to be installed.


Hope this helps or is at least a starting point. Good luck!