1998 LS 2DR Auto 4.3L 4X4 (133,401)
Multiple problems!!!
~4x4 is not engaging, i hit the button on the dash, the light switches over, i hear the transfer case (swooshing noise) but nothing happens.... only the rear wheels spin.... HELP!!
~The 11 blade clutch fan (75$) keeps braking(3rd time replacing), it has a metal base with platic fins, the plastic keeps braking from the metal and causes the fan to wabble during idle.
~Indicator light on the dashboard doesnt tell me what gear im in (P,R,N,D,3,2,1)???. Checked for a fuse but none for just for the gear selector
~The switch to guide wich direction the heat or A/C goes does not work, on the console for the climate control there are three *****, one for the speed of the fan, the middle one is for hot or cold, and the far one closest to the passenger side controls which vent the air goes through such as the defroster, towards the feet, towards the roof, etc,etc

 

Your 4x4 and A/C problems could be from the same source, check your vacuum lines under the dash (behind glove box) to see if they have AT fluid in them if so then you will need to replace the vacuum switch on the transfer case, GM replaced the old style with an updated version that is not supposed to suck fluid into the A/C lines. A friend of mine had that switch replaced at a tranny shop and they swore that the got it on correctly but afterwards found out different, mark it so that you don't get it rotated wrong way.

As far as the fan goes just check some of the threads for an E-fan conversion, it will get rid of your fan problem by replacing with electric fan(s), it will add some HP tooo.

Also check your vacuum lines to make sure that the vacuum actuator under the battery is getting proper vacuum to make the switch to 4X4 at the front axle. If that is working then you will have to check the TCCM switch and the encoder motor (which actually makes the transfer case switch) to see if they are getting the proper signal to switch from 4HI to 4LO.

Good Luck..

 

You should check under your hood by the brake booster for proper vacuum hose connection FIRST there is a check valve with several vacuum hoses connected there and the supply to the front axle actuator as well as the HVAC mode actuators are both in that connection. There is also a vacuum storage tank right there mounted in the left front fender, make sure the hose is attatched to it. The problem that 20blazer00 spoke of with the ATF getting into the HVAC system is USUALLY only associated with the 2002-2004 model years, but these did use the same faulty vacuum switch on the t-case. Please let us know what you find.

 

the A/C problem is your upper/lower mode door actuator....its a pain in the *** to get to though...you have to take out the whole dash. or...if u have a plastic welder u can go through the glovebox. either way...plan on spending close to $400 if you take it in to a shop.

 

+1

Sounds just like the problem I had when a hole rotted in a rubber vaccum line.

 

Yea you have to check the rubber vacuum lines first, like I said before. Don't just assume that the mode door actuator is bad and start tearing (and definitely CUTTING) the dash out. Actually there are four of these actuators anyway. It could even be a rotary vacuum valve on the HVAC control head, but we will address those posibilities AFTER we eliminate the hoses!