I have the same problem yet I get out of work at 3am when its 5 below zero in New England and my 45 min ride home really sucks and steal toe boots at that. So I recently changed my heater core and the process is not easy bring your tools and alot of patience. I think the actuator ( that little white plastic piece on the box) is not turning or is disengaged so I may have to go back in and find the problem here some pics of the actuator and dash removal. dont think my pics came through sorry need help in posting pics too I see.

 

My 98 blazer is doing about the same thing as everybody else has. i don't think it is so much as the door by the accelerator pedal. i have the "HEATER AC CLIMATE CONTROL SWITCH" off the panel, and i can hear vacuum leaking from the switch. unless someone else has notice this i would say replacing the switch would solve the problem. I'm going to do it 2moro and ill let you know. If you take the switch apart you will see the little maze the vacuum is directed to, and that's is where I'm hearing the leakage.

 

Check out my post #63 on page 7 of this thread, if you take that switch apart and the rubber is slimy, puffy and doesnt really fit in there right then you probably have the same issue i had, your transfer case is overfilled because the seal at the rear of the transmission is leaking and it allows the fluid to overfill the transfer-case, when the t-case gets overfilled it allows fluid to sucked into the vacuum lines through the vacuum switch on the t-case that sends vacuum to the front diff actuator when you select 4x4, if you shut the engine off while 4x4 is engaged, the release spring pressure in the front diff actuator sucks the opposite direction and pulls fluid up the line out of the t-case, now You have a bunch of transmission fluid in your vacuum lines and eventually it gets into the reservoir and all of the climate control Vacuum actuators. I explained more about what i did to fix mine in that other post i mentioned. Good luck.

 

New guy here! This may be one of the most useful threads I've ever read and I belong to A Lot of forums! Thanks for all of the great input!

I am having the same issue with the 2001 Jimmy I purchased a couple of weeks ago. I have the shifter on the floor. I haven't attempted to remove the console yet but just eyeing things up I can't see how you can get the console off over the shifter?

Has anyone removed their console with a floor shifter?

Thanks,
Tom

 

Have not worked on a floor shift blazer but most cars have some kind of release clip on the back side of the shifter **** and the whole top handle Lifts off leaving just the shaft in place, hopefully someone who has done it will chime in with a sure answer, until then look at the back of the shifter (the side facing the dash) and see if theres a slot or hole back there, i think if its a slot theres a clip you just pry out with a small screwdriver, if its a hole there may be an allen head set screw in it.

 

Thanks dimblazr. but it turns out it was not the same issue. i went to junk yard got similar parts and they were all the same way. (not swollen or puffy) but more lube in them. So i put silicone grease in it and solved the problem. the switch was not leaking as i said earlier. I would suspect that if the t-case was being filled with transmission fluid, you would have noticed loosing fluid in it tranny. Also i took a hose and hooked it to the vacuum line under the hood and hooked them directly to the vacuum canisters and they all worked fine. I believe the biggest issue was the dumb iea that Chevy did was where they hooked up the vacuum line almost directly with the PCV valve. If you fallow it and see, the PCV valve goes bad, it will blow hot and dirty air to the rubber hoses and rot them like most people have found. So i would say replace your PCV valve often.

 

Thank you DimeBlazr! Haven't had a chance to check it out yet between work and constant sub zero temps! Wind chill right now about 15 below!!

 

I am trying to purchase an AC Delco defroster valve replacement for my 2000 Blazer LS with the C60 RPO (manual climate control with AC) but can only find schematics and parts lists online for the C68 RPO (automatic climate control, AC Delco defroster valve part #15-50554). Does anyone have a pdf of the C60 system to post or at least access to the AC Delco part number?

 

Will this help?

A/C & HEATER MODULE ASM. Fits: Kodiak, Topkick | Nalley Buick GMC Brunswick

 

I don't think this is it, but thanks. These look like parts for the big trucks of that era. I'm looking for the schematic for the HVAC system of a 2000 Blazer LS 4x4 SUV with the 4.3L V6 engine that has the manual-controlled HVAC system. I need to order the "windshield defroster valve" (which is part#15-50554 on the "auto-climate" controlled system) but cannot find the correct part number on ebay or anywhere else unfortunately. The valve could be the same part number for both the manual and the auto systems, but I have no way of confirming that at this point so am uncertain and hesitant to order the #15-50554 valve.