Engine/Transmission (1998.5 - 2002) No AC or 4WD

[TDaub]

What do the AC/heater and the Transfer case have in common?



I had to replace my heater core a while back. After fighting with the dash for many hours (take it out, put it back. doesn't fit right, take it out, etc) I finally got everything back to where it is supposed to be (minus the shattered dash pieces), now all I get is hot air, have to by pass core in summer. Get cooler air that way , but not nearly as cold as it should be.



Tried to go int 4WD the other day, no dice.



Problems found:

No Vacuum to Transfer case

Recirc door does not open (probably vacuum)



air director Does direct air to appropriate location. (IE floor, defrost, etc)



Any Ideas?

 

[cerberusiam]

You have a vaccuum line disconnect somewhere. Both of those components use vaccuum to operate.

 

[TDaub]

I understand that, but is it one line or 2. Do they have a specific line in common, but separate from the others?

 

[jgillott]

Main line splits directly behind the valve cover on the firewall. You may have to pull a little of the insulation matting to see it on some trucks. Check to see if it disconnected there.

 

[cerberusiam]

They split somewhere, likely where was suggested. Or the line is cracked and\or broke at the vaccuum pump. Unfortunately on these old trucks you will have to trace all the lines looking for problems.

 

[gtwitch]

I suspect that this is the same thing that happened to me the other day when I changed the fuel filter on my 99 and I inadvertently pulled the tee apart on the vac line right above the filter that goes to the dash thru the firewall. It disabled both the heater/AC and 4WD!



gtwitch in Wyoming

 

[Wiredawg]

I had this happen... you need a vacuum gauge and tubing. I started at the pump and worked away, pulling apart each connector and checking vacuum. Found melted vacuum line just before it goes into the firewall. My exhaust brake back pressure gauge brass tubing separated and melted the line.

Wiredawg