HVAC problems, hissing controls

mattfu · Post by **mattfu** » Sat Sep 30, 2006 9:01 am

Split topic-HJ

i wish i understood the controls of the hvac system better. how many different components can i expect to have to replace along the way? does the contaminated lines from the t-case switch go directly to the selector switch? or is there a transducer inline? where do each of the three vac lines go to? are they all on a common vac system or does each line have a specific purpose ? basically i have the hissing sound and no control of the vents what so ever , i am trying to figure what i will need to replace before i tear things apart. i realize the answer is replace whatever is broke or contaminated with ATF , any advice is appreciated , has everyone headed for the dealership after all was lost, anyone done all the replacements themselfs after major contamination and problems?

Post by **HenryJ** » Sat Sep 30, 2006 9:51 am

The transfer case lines do not go directly to the HVAC. They do all work off of the same vacuum system though.

If you have a hissing at the controls, you have a leak and the transfercase switch may not be associated with your problems.

Check for a dislodged line, or faulty control.

mattfu · Post by **mattfu** » Sat Sep 30, 2006 9:59 am

thanks hj , but where should i start, open the dash ? or start tracing lines from the t-case ? the hissing is only when the air controls are on , no hissing in the off position ?

Post by **HenryJ** » Sat Sep 30, 2006 2:21 pm

Start where you hear the leak.

20Blazer00 · Post by **20Blazer00** » Mon Oct 02, 2006 5:48 pm

If I remember correctly I saw a photo on a site that showed most of the vacuum lines behind the glovebox. Just push on the metal loop at the top of the box and it will fall forward exposing the lines and connections. You should be able to go from there.

I have read on other threads here about the transcase vacuum switch and some have found fluid in ashtray while others have gotten to it sooner and not had that problem.

Sounds like you getting it sooner rather than later.

Good luck hunting down the bad line.

04crewvt · Post by **04crewvt** » Mon Oct 02, 2006 5:53 pm

Thats also a great way to clean out your glovebox BTW.

mattfu · Post by **mattfu** » Tue Oct 03, 2006 6:52 am

thanks guys im picking up the switch in an hour , might tackle it today yet.
my glovebox is empty so it will be fast haha but the center console box .. man they are a junk magnet.