Heat is always blowing, and hearing creaking in the dash.
 

98 Blazer 4x4


Symptoms:
1. Heat is always on. If I turn the fan speed to off, it blows lightly, but is still on and very hot. I handle this by turning the vents to the closed position, but ultimately the heat still comes out.

2. If i turn off the radio, I can hear a creaking in the dash around the glovebox area. It creaks for about 3 seconds, then clunks, then pauses for 5 seconds then starts over again.

3. I can't get fresh air to enter the cabin. When I press the button, it blinks and does not ever go solid. Same with the AC.

Observations:
When i set the knob to defrost, it directs the air properly, same for all the other settings.


Questions:
1. Should my blower motor always be running? I would think that having the switch in the off position would disable the blower motor completely.

2. What is the creaking sound? I assume it's a door (actuator).

3. Anyone experience similar issues?


The easy stuff:
After reading around today, I found that the actuators are vacuum operated and that I should check the vacuum ball under the hood (near the drivers side quarterpanel?).

Fuses, I'll check all the fuses tonight.

Any other ideas??

The blower motor should shut off when the HVAC system is turned off. It should not continue to run.

Sounds like the rest of your vacuum doors are doing what they are supposed to. The RECIRC mode is only available in MAX A/C.

Your creaking problem sounds like a blend door actuator failure. This is the only electronic door in the HVAC system.

Fixed!
 

I just wanted to respond that I spent the money on a blend door actuator, and that fixed it! The auto climate control version was about 125 at a local parts store (after haggle).

It only took 15 minutes to fix.

You need a 1/4 drive ratchet with a 7/32 socket, and that is all. Just drop the glove box (release located in upper left side). Then disconnect the tube going into the round rubber vacuum deal, then move the rubber vacuum deal up and over. Behind that, you can see the actuator. Remove the power, remove the two screws (kind of a pain, but manageable). Remove the actuator by moving it upwards. Installation is the reverse of removal.

Blend door motor
 

Ok, same problem as you.But, I live in Australia, so parts not easy to come by. Was trolling the net, looking for a blend door motor but not having much luck. Even the GM sites didnt seem to list it correctly.The part which looked right on the exploded view was listed w/o ac. I take that to mean no a/c. So I googled the part no. on the actuator. Success! This brought up parts which looked right. I then found the generic part no. on one of the sites so then I rechecked ebay. Absolutely hundreds of them. This part came out on a hell of a lot of vehicles. So I thought, I will check out a local GM product called a Commodore. I knew from experience they have a similar style a/c compressor. The blend door motor was identical in appearence, but on closer inspection the plug pin layout was reversed. I paid $20 aus for two of them. Took them home, pulled one apart. Just a motor and some gears on a board. The Blazer one has components on the board.So, I lined up the large cog with the markings on the small blue cog (this tells the climate control where the door is), Put a mark on the large white cog and removed it. I then reinstalled it into my old actuator, making sure the blue cog lined up the same. Put it all back together, tested it (plugged it in and run car, change temp, see that it moves! BE PATIENT!) and reinstalled. Works a treat, all for $16 your money. SO, just scout the junkyards and look for one that looks like yours. My replacement also has a yellow plastic collar to support the output shaft, so I fitted this as well. :icon_google:

15-72971 is the generic part no. If you look it up on ebay some of the postings list the other cars that it fits.

Same issues as others far as blend door issue. My question is Could it be the door itself? I have been searching for possible fix for blend door. I think it is just the door. As I can see the actuator cycling. Also I did get replacement actuator, 45 dollar. Plugged it in and it cycles.. If the door inside the box is warped or wore out can you fixit.

Ok Blend actuator motor. I am working on my 99 jimmy, same problem heat all the time. I took my motor out today and plugged it in and turned on the key, I didn't start it, then worked the temp control. My old motor would go from side to side all the way then back to it's original position, hot. I went to Autozone and got a new motor, 44 bucks. Got it home wrong one. I have the computor climate controlled system. The motor for this system has 5 wires part
number 904-106 and the mechanical one has 4 wires, part number 904-100. The 100 is 44 bucks, the 106 is 138.00 bucks. I will try and get it on in the morning.
Jack C.

Thanks!
 

This disscusion really helped me out. I just bought this blazer and it came with a ton of problems that the seller never said anything about. It's been in a bad crash based on all the things I'm finding. The whole A/C Heater system must have been replaced because I replaced the blend door accuator. It had a 5 pin for auto temp control when my blazer has the manual temp control. So i bought a new 4 pin accuator and now I have hot and cold air! Thanks so much! BTW I have a five pin accuator laying around if anyone is interested

I need the 5 pins
 

So it looks like I'm in the market for a five pin. How much would you like to sell it for?

5 pin
 

NOt 100% that it works but i'm guessing that it does. $25 bucks its yours. I can put it on ebay.