2nd Gen Non-Engine/Transmission Trying to help a buddy fix his defrost....

[KBennett]

My friend's '97 is not blowing air out the defrost vents. The vacuum lines look like someone messed around with them but I don't see any breaks and I thought the system defaulted to defrost when vacuum is lost.



Any thoughts?

 

[DieselDoghouse]

I don't know what you've tried so far but:

1. check 4•4 CAD and Cruise control operation - if bad vacuum pump may be stuck.

2. pull vacuum line from pump (behind P/S pump) and check. Sometimes the valve sticks and a shot of WD-40 will free it.

3. trace vacuum lines from manifold at firewall to line to heater - esp check the elbow coupler - mine went south early.

4. may want to check couplers between hard lines and hoses under truck - the two at the TF case can get 'oiled' and soften up.

5. now its time to check the 'dash lines' selector valve, and vacuum motor to ensure its not jammed.

Good luck!

 

[KBennett]

DD, thanks for the response.



I went over yesterday and we drove it around. The cruise works and the selector switch will switch the between the upper vents and the floor vents but not the defrost.



Where is the vacuum motor located so I can troubleshoot it?

He is a member of the cracked dash club so we will probably be pulling that apart here soon.

 

[the whale dog]

The defroster vac solinoid is on the drivers side just above the hump I do not remember having to remove anything to get to mine , you could hear the leak when it was switched



the dealer changed the selector twice in two years and it turned out to be the hose that runs behind the hood weatherstripping had a hole melted in it it would only sag when hot. and hit the turbo cut off 2 inches and stuck it back on the elbow

 

[KBennett]

The defroster vac solinoid is on the drivers side just above the hump I do not remember having to remove anything to get to mine , you could hear the leak when it was switched

That's the info I needed!

I looked under the dash in the area you described and the defrost actuator is missing. The previous owner had bailing wired it so that is would stay closed. I removed the wire and he now has partial defrost and partial vents which he is satisfied with for the winter.



Who is a good source for the actuator? Dealer?