Air blend not working at all
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Joined: Mar 2008
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From: Ohio
Air blend not working at all
So, my HVAC system on my truck has been stuck on defrost for over a year. It's time to fix it.
Temperature control works, found a cable hooked to it. Blend doesn't work, tore the dash apart enough to get to it, and I've got colored tubing with nothing but air inside running to a switch... So it's vacuum operated...
Any idea where the other end happens to be? Can't find a damn thing in the factory service manual, maybe I'm not looking in the right spots.
Found this while looking to ghetto rig a mount for my stereo and fix my speedo/odo. That was an easy fix, cable fell out of the gauges. Just gotta get that air blend working...
Temperature control works, found a cable hooked to it. Blend doesn't work, tore the dash apart enough to get to it, and I've got colored tubing with nothing but air inside running to a switch... So it's vacuum operated...
Any idea where the other end happens to be? Can't find a damn thing in the factory service manual, maybe I'm not looking in the right spots.
Found this while looking to ghetto rig a mount for my stereo and fix my speedo/odo. That was an easy fix, cable fell out of the gauges. Just gotta get that air blend working...
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Joined: Mar 2013
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From: Eastside Tucson AZ
Engine and transmission are gonna make a difference. & on yours, probably whether it's 4wd.
My truck is an automatic, 4wd, V8. '95, so the transfer case isn't vacuum operated.
On mine, there are bunches of vacuum ports on the intake manifold or plenum, but only one of the ports has anything attached. It provides vacuum to the cruise control, some emission thingy, and I presume the hvac systems. BTW, there are three vacuum solenoids, two are up in the dash and then there's one down on the right lower side that controls the air source--cab air vs outside air.
So diagnosis time, does your cruise control work? I think rather than starting inside the cab to look for a disconnected vacuum line, you need to start at the vacuum source--on mine it's one of the ports on the passenger's side of the intake.
I actually went out and looked (had to check my oil anyhow) and I can't see where the vacuum line passes thru the firewall. But I think if you trace the hose path, somewhere you'll find a line that's come loose (probably the lines themselves haven't gone bad, tho.)
My truck is an automatic, 4wd, V8. '95, so the transfer case isn't vacuum operated.
On mine, there are bunches of vacuum ports on the intake manifold or plenum, but only one of the ports has anything attached. It provides vacuum to the cruise control, some emission thingy, and I presume the hvac systems. BTW, there are three vacuum solenoids, two are up in the dash and then there's one down on the right lower side that controls the air source--cab air vs outside air.
So diagnosis time, does your cruise control work? I think rather than starting inside the cab to look for a disconnected vacuum line, you need to start at the vacuum source--on mine it's one of the ports on the passenger's side of the intake.
I actually went out and looked (had to check my oil anyhow) and I can't see where the vacuum line passes thru the firewall. But I think if you trace the hose path, somewhere you'll find a line that's come loose (probably the lines themselves haven't gone bad, tho.)
Last edited by Brian in Tucson; Jul 30, 2013 at 02:28 PM.
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From: Ohio
3.9L, 5MT, no cruise, no A/C, no frills at all.
I'll have to check her out tomorrow after work... as well as re-repairing the speedo... Cable fell off again. Time to make sure it stays.
I'll have to check her out tomorrow after work... as well as re-repairing the speedo... Cable fell off again. Time to make sure it stays.
also where the heater hoses enter that firewall there is a vacuum line with a check valve on it. it everything is connected i would suggest checking to make sure there are no cracks in the lines