I just recently got a 1988 S 10 Blazer 4x4 2.8 5 speed . It runs really well but when
I engage 4 wheel drive it seems the front axle's are not engaging . Also the 4x4 indicator
light always shows 4x4 low , no matter where you put the shifter , and finally the heater/ac only blows out of the defrost vents no matter where you set the slide lever. Could all this be
vacum related ?. My main concern is the 4x4. I really need all wheel drive when the snow comes.
Any help would be appreciated.
Thanks
Steve

 

I thought darn near everything behjind the dash was vac operated. Last i remember they had dashpots on the a/c heater box moving the flaps around, vent,defrost, floor ect. definatly check for a leak under there. might solve the 4wd problem allat the same time

 

Sounds vacuum related any one of a number of things could be the problem...

There is a 4wd vacuum 'switch' under the battery tray, another one on the side/top of the transfer case check those

Also check your vacuum hoses under the hood and your canister for leaks, etc.

Under the dash there are also some vacuum hoses to/from activating levers etc. slight possibility the heater/defrost issue is a broken mechanical linkage and not vacuum...

 

I found out there is no vacuum to the vacuum actuator under the battery tray.
I ordered the Posi Lock kit because it seems to be a much more reliable method , I'll post
my results after I recieve and install it. Thanks for the tips on the vacuum/broken cable
info for the heater/defrost situation. It sounds like most of my issues are vacuum related so
I'll check out the the hoses and cable this weekend.

Thanks again
Steve

 

I installed the posi lock cable kit today and I must say it is great. The installation is not
bad , the hardest part is finding an 11/16 drill bit to drill the firewall. I just followed the instructions and all went well. So the 4x4 is working fine now but I'll have to do some vacuum checks now for the heater/ac. Although some may feel like the posi lock kit is a bit pricy , once you see how sturdy and well built the cable is you'll feel much better about it.

Steve