dreaed hisssing noise

[robv]

my 2000 s-10 4x4 zr4 has the hissing noise coming from the dash and can't switch the vent stuck on face blow ,
if I plug the t/c vacuum line will it stop the hissing,,and so far I haven't found trans fluid in the vacuum lines how can you pin down the problem down with out RR each of the switches?? is there a way to test the switch on the dash?? I can't find a leek in any of vacuum lines.can anyone help with this, I have read the other posting but doesn’t say how I can tell if it’s my T/C vacuum switch??

[HenryJ]

If you don't have fluid in the lines at the transfercase switch, then I suspect you will have to replace the HVAC control switch if that is where the hissing is coming from. It is an assembly and not serviceable normally.

[robv]

is there a way to test it like with a vacum tester or something ?? it's 110 bucks i'd like to know if its bad before i buy a new one

[HenryJ]

I would say if it is leaking it is bad.
How about trying a used one?

[Jongo88]

I picked mine up at the junk yard for 5 bucks. Just get one from a two wheel drive.... I replaced every vacuume pod too. The main one that was full of tranny fluid was the top one by the gas peddle. The other one that was full is the one in the glove box. I got all of them for 10 bucks.

[Adamr916]

if it was full of tranny fluid, then shouldn't you of changed out the t-case switch first?

[kxracer]

I never really though much of it, but mine makes a hissing noise in the 'vent' mode. I can still change through all the options, and no air leaks through the vents. Could this cause my 4x4 problem at all?

[Jongo88]

if it was full of tranny fluid, then shouldn't you of changed out the t-case switch first?

Did you read my sig???