Only blows out of Defrost.

[Swamp Donkey]

My Dad's 1998. 5 24v is only blowing out of the window defrost vents. He has had a mouse making a home in the blower motor. He caught the mouse, took out the nest out of the blower motor. Now is this a coincidence that the switch could have gone at around the same time or has the mouse got another nest where the flapper moves? Is there an easy way to check the switch?



Thanks.

 

[Neal Cassady]

Don't know about the 98 trucks but on the newer trucks the blend door is controlled by a vacuum line.



Dave

 

[Morphious]

Check your vacuum lines, I bet you have one chewed in two somewhere around the switch or under the hood.



Morph.

 

[MidwestMotorman]

vacuum

I will third the motion on the vacuum line as the cause. Due to the diesels clatter, it is hard to hear the vacuum leak from the line. Check under the dash and under the hood.

 

[Xgunfighter]

Mine also

The default position for the HVAC is defrost when there is no vacume to the head unit. Mine did that and I found the vacume hose at the pump was cracked at the 90 degree fitting. Dodge can't sell the fitting, the whole line from pump to firewall comes as a unit. Under warrantee.



Hopoe this helps.

 

[Swamp Donkey]

So do I take apart the dash and and start at the switches? Do the vaccume lines go into the engine compartment and back into the cab? I will poke around a little, but it would be nice if I even knew which ones were vaccume lines!



Thanks.

 

[Dieselnerd]

SWAMP DONKEY, you can get at most of the stuff you need to look at by removing the piece under the steering wheel. It's not that hard to do. From there you can reach the switch with the vacuum hoses on it.

 

[Bigramguy]

I would start under the hood first,with the line off the vacuum pump,and follow back from there. No tools required. Check all the lines under the hood,as there may be a leak somewhere else,such as the cruise. Line comes off vacuum pump to a tee on the fire wall (behind master),and the one line across firewall to heater controls,and one back towards battery for cruise (if you have it). Mine has already broken at the 90 on the vacuum pump and chaffed through the line on the PS lines.

 

[Joe G.]

Check your service manual. You may be able to roll the entire dash board assembly back so you can get at the defrost/heater stuff from on top. That's what I did when I had trouble with it on my '95.

 

[Swamp Donkey]

Thanks, I will dig into it in the next couple of days, we are going hunting so I will have a bit of time during the day to look around. After Swamp Donkey's!

 

[Turbo Thom]

On the 96 there was a re-call on the vacuumn line where oil was getting into it and causing a problem. I also, somehow, got the line down on the turbo and burned it into. If anything happens to the vacuumn line the vents on the dash is the only place of exit.



Check it out.



Preston

 

[MEGARAM]

MEGARAM's vent system experienced a similar problem while on vacation near Knoxville, TN a year ago. When I popped the hood, I found one of the tape/tie wraps that hold up the vacuum line had come loose, allowing the line to drop down onto the turbo. The line melted instantly. Repaired the line and the system was back in business.

 

[KGoode]

Check the vacuum line above the turbo, mine melted from the heat which left me with defrost only

 

[Alaskaskiff]

I had a similar problem and it turned out to be a bad vacuum control behind the airbag sensor (it has 2 positions and the second wasn't working). It probably failed due to the previously mentioned oil in vacuum recall and assoc check valve. I would look here after checking the others. It can be changed just by removing the bolster under the steering wheel and the plastic cover on the front of the airbag computer unit. I used a ratcheting angled phillips from craftsman due to the small in line clearance to remove the 2 screws holding it on.