'99 3500 Dually, the heater only blows out to the defrost. Great for cleaning the windshield, but my legs are freezing! Vacuum hose, or malfuctioning cable? The **** moves freely, but I don't hear any movement in the ducts. Any thoughts?

 

Both your problems (4 wheel drive and vent selection) are more than likely vacuum related. You have to follow the lines. There are also check valves along the way.


Good luck with your ride.

 

Try to find the vacuum diaphrams under the dash. Pull the plastic hose off and see if you have any suction. If not may want to trace out the lines under hood that supplies it to cab. Make dure no cracks or loose fittings. Make sure everything is hooked up on back of selector in dash also. Should be able to see the diaphram move as you move the selector or pull hose off.

 

Good advice, thanks guys!

 

You guys were exactly right. It was the main vacuum hose not hooked up. Took care of everything as soon as it was put back together. Thanks a lot for the help!

Dave

 

Sure is nice to have an easy fix once in awhile. That's great!

 

i had a similar problem awhile back after my heatercore puked, but mine turned out to be the electrical motor that operated the door had anti-freeze in it and seized up, mine was for the hot and cold though, some days i had hot, some days i had cold, then it was just stuck on cold i think