As the title says all my heat and ac are going to defrost. My vacuum lines are all connected and I have vacuum at the pump, at the 90 on the fire wall and at the 90 that turns into the firewall to the hvac. I do not have vacuum at the switch. I cannot seem to find a pin out, for lack of a better term, for the connection to the controls. I am assuming the black tube is the one supplying vacuum to the controls. Not sure that matters since I can feel no vacuum at any point on the connector. I am seriously thing of capping the line at the passenger side firewall and just bringing a new one thru the driverside straight to the connector. Does any one know if that supply line connects anywhere else before it goes to the controls? Or does any one have a map of the HVAC vacuum lines?

You got me  last time I had my dash out I think there was only one line and it was black going to controls. You're on the right track with your thinking though. I'm sure while you're running the new line you'll find the problem with the old one 

 

 

There is a connector to the right side of the fuel peddle, half way between the ash tray and fire wall. 

 

Check the vacuum hose connectors for rot.

Edited April 12, 20196 yr by IBMobile

Did the supply hose running to the passenger side get crushed?

17 minutes ago, trreed said:

Did the supply hose running to the passenger side get crushed?

I have vacuum at the 90 that turns to the fire wall on the passanger side. So some where between there and the selector I am loosing the vacuum. Really dont remeber how that line runs on the hvac box.

 

I will have to check the connector near the throttle that @IBMobile mentions above. Not one of the more fun connectors to get to.

 

56 minutes ago, trreed said:

Did the supply hose running to the passenger side get crushed?

Good point

Seems that one would hard to crush since buried in all the wiring along the cowl. I had to dig mine out of it.

 

Back when I rebuilt my HVAC box the line coming thru the fire wall had gotten brittle and I had to replace a piece of it. Maybe it has cracked further down the line into fire wall. Hmmmm.

That is a possibility as it runs the whole length of the HVAC box.

1 minute ago, trreed said:

That is a possibility as it runs the whole length of the HVAC box.

My thinking is it ru s straight to the connector at the throttle then to the selector. If thars the case then I am going to run a new line from drivers side thru the firewall and to the selector if all else fails.

It should run directly to the selector.  then it goes to the three motors.

Well I managed to cobble together enough old and new pieces to get vacuum to switch and it works. But now to find the right size new stuff to fix it right. Finding vacuum stuff of the shelf arond here sucks. Too many different sizes.

3 minutes ago, dripley said:

Too many different sizes.

At least you have choices

Cut a piece off of both ends and take them to the parts house.  There they can match the inside diameter of vacuum hose needed for the splice.. 

Took the whole home made line with me. 

I bought 8' of air brake hose and connected it to the manifold fitting on the drivers side. Then thru the fire wall straight to the selector. That part is mostly fixxed

 

I still have some air at the floor in all settings. The floor setting is much stronger alone, with a little bypassing to the defrost. Set it on floor/defrost amd the defrost gets stronger. Used to have seepage at the defrost in those settings but now the floor instead. I have had that seepage seems like since new. Never gave it much thought. Sounds like I got some more chasing to do, but that is a bigger job than I am tackling right now.

When it comes time ill rebuild my vacuum system completely with air brake tubing. Never worry again. Even on my 1996 gasser I will build it as well with air brake line. A lot of the mistake is making sure to route away from heat and friction.

53 minutes ago, Mopar1973Man said:

When it comes time ill rebuild my vacuum system completely with air brake tubing. Never worry again. Even on my 1996 gasser I will build it as well with air brake line. A lot of the mistake is making sure to route away from heat and friction.

I should have said tubing instead of hose. I believe the oe tubing going thru got cooked from the heat of exhaust. Never quite ubderstood why that tubing crosses the firewall just to come thru and go back to the side it started from. 

Because this body was more designed for the V8 gas engine than the I6 Cummins diesel. This is why the vacuum pump was added and the vacuum comes out of the dash on the passenger side. As you see the 3rd gen up stopped with vacuum and went to electric stepper motors.

Do I see another mod coming 

9 hours ago, Dieselfuture said:

Do I see another mod coming 

 

What are you asking me to tear out my vacuum system and replace it with all air brake line and upgrade? 

11 minutes ago, Mopar1973Man said:

 

What are you asking me to tear out my vacuum system and replace it with all air brake line and upgrade? 

I already have a head start on you.