RJC

I have a 1993 dually W 350 and I can get the defrost to switch over. I have heat and air through vents but can get it to switch over to defrost. Heading out on a trip this weekend and can sure use some help.

Thanks

ofcmarc

Start checking vacuum lines from the heater control to the mode doors .

#2isgreen

Is it possible for one of the vac diaphrams that move the door linkedge rods to go bad?

maybe368

In 2 words, Of course!!! It is easy to check them, just put any vacuum pump on it and see if it moves...Mark

archer

My 2002 started out like that then lost all control to vents, only had the defrost, was still hot though, and what it ended up being was a hole in a rubber plug on the main vacum line at the fire wall under the hood. It was located about where the drivers side wiper blade is, good luck

#2isgreen

thanks

big hose

mine did the same thing or still does the control by the gas pedal is the one that runs the def. mine sticks you can reach your finger in one of the holes by the gas pedal and push it

#2isgreen

Any hints on where I can find new controls?

maybe368

I just did a search and it appears that there are no generics around. I would think possibly a dealer and try a crossover manual, because I bet they used the same or similar in many vehicles. Good luck Mark

maybe368

Dodge still has them for the 94 and later. Here is a pic. look at #s 5,9, and 10. I bet you can make 1 of them work...Mark

#2isgreen

Thank You. Thats a HUGE help!!
I figured out two things, first, my "outside air" door is positioned so i can only get air from the cab.

Second: if i open the glove box there's a control rod, with the truck running, i can grab that rod and pull it towards the passenger side of the truck and it pops the control door by the trans hump and sends air to the windshield!!

so I'm thinking i just need more vac. or make better use of the vac i have. any ideas how to seal the little rubber slide on connectors to the control diaphram things? maybe some liquid teflon goo?

furious70

When we took mine apart to fix the evap the result was the lever for one of the controls doesn't go the last 1/8", I have my glove box off and have to yank it closed. Sucks, but I don't drive it enough to tear it all back apart to try to fix it.