Just bought this 2001 ZR2 and actuater switch went bad on transfer case which had vacum lines runing to it and small amount of fluid came out of them when I pulled them off of switch.I was told if the actuater switch lines had fluid in them it could have been sucked into havac system and messed it up.Was wondering if this could be causing heater control not to change from def. to floor heat or dash vents.It blows out of all of them no mater where you turn control on dash.Anyone else had this issue? By the way I replaced actuater switch on transfer case.
Thanks

 

If you suspect transmission fluid has gotten in to the vac system, then you need to get under your dash and pull connectors off of the vacuum actuators to see how extensive the contamination really is. It is possible for it to lockup actuators.

 

Thanks I just read another post where you helped someone else out with a simular problem.I will check the hoses out.
Thanks again

 

I pulled the vacum lines off the back of the mode selector switch and some off the modules before the switch and found no oil in the lines.Could it be the mode selector switch went bad from the acturator switch going bad on the transfer case?

If iI put a hose on the acturators under the dash and suck on the hose the doors and vents move but just seems the mode selector isnt giving vacum as no mater where you turn the switch you do not hear any vacum or change

 

The common issue with these Blazers when the Selector goes bad is that the vacuum hose On the Drivers side between the ABS system and the Cruise control that is mounted on the Firewall come off a nipple that is in the Fender. Look there for a 6" hose that has no home.
If that hose is missing a home then stand at the drivers fender, find the bolt for the ABS bracket that is furthest to the right. reach directly under that bolt until you hit the fender, the nipple is there. When that bolt is sticking into your wrist and hurts, That's about the time your fingers will feel the nipple., your will. It's tough but you can get it back on without removing anything

 

Figured it out it was the mode selecter switch on the dash as it had vacum going to the switch

 

Well The mode selector switch was bad and it does change the air flow now but air still comes out of the dash vents all the time and the defroster does not seem to blow as hard as it should.I looked at the differnt actuaters under the dash and they seem to move when you change the setting on the mode selector on the dash .
Any Ideas?

 

Here is a schematic I had found:


I do not have time right now to look into what might be causing your air flow problem, but have a look at the schematic and you may be able to see..

I know that the picture says 97, but it is very similar if not the same for the 98+ trucks as well.

 

Thanks
Any input you would have later would be helpfull

 

Sounds like you have a problem with the defrost door. I hope that it is not inside the HVAC housing. Can you manipulate the defrost actuator rod manually and see how it impacts the airflow?