clicking noise fromunder the dash
 

hello everyone just joined this forum - need some help - my 1994 blazer started making a clicking noise from the right side under the dash when the air is on but goes away in about a minute and is fine until i shut the ignition off and it clicks for another minute and quits. Sounds like plastic hitting plastic _ any ideas as to what it is .

It's probably the vent door at the fan. My '94 yukon had the same problem.

I'm having the exact same problem with mine. The clicking/banging is pretty loud and I can feel that it is coming from directly behind the blower motor. The clicking begins when I turn on the ignition, turn off the ignition, or switch on the AC, lasts for about 15 seconds, and then stops until the the ignition or AC is turned off.

Does anyone have a diagram or general instructions for replacing/fixing this vent door? Also, a diagram of the HVAC system would be really helpful.

I am also no longer able to get any air out of the dash vents. Is this the same problem or two separate problems? Defrost and floor vents work fine. Heat blend also works fine. Thanks for the help.

Noise
 

I have a 93 k1500 and when i turn the key on and off it make the same noice with out the a/c or heater on and i can turn it on and off and it will make it to. I can take my heater fuse out and it will quit so is it an electical thang or what like some kind of relay or resistor. It is real loud.

I'm having the same problem, I just got my blazer 92' from my mother in law excellent condition! Just needs a window motor struts for back window and the darn clicking noise. Anyone with any knowledge on what this is or how to fix it?

Yea mine is real loud i would pull the fuse out but man it is real hot out and plus when it rains i dont want to stop beside the road and put it back in so i can see. If any nows how to fix this please tell got it is a pest and it is weired people look at it like whats going on is it going to bolw up or what is that they ask?

Did you ever figure out what the problem is? I have the same problem....my A/C doesnt work but the blower motor does. I get a loud clicking when I turn the ignition to the on position and when I turn it off I get the noise for 6 to 10 seconds...

I took the leads of the blower motor (DASH APART) no electrical leads and turn the ign to the on position, noise was still there....

I took some pictures of the dash out and blower motor exposed ( this is missing the ECM module and plate) ..I turned the ignition to the on position with the electrical leads removed from the blower motor and the clicking noise was still there. I saved some pictures in the photo gallery labeled..." a/c blower motor 1994 blazer"........I have to rip out that mess of back plastic!!

and my a/c doesn't turn on....pump is fully charged....checked it....could this flap door (WHERES THE DIAGRAM!@#$%&!!*@$)

The 92+ Blazer/Tahoe Sport trucks do not really have much of anything in common with the 2nd gen K5 Blazer (73-91). Pretty much everything in the K5 was either cable controlled or vacuum controlled as in the later years. The NBS (92+) Blazer/Tahoe Sport trucks have electronic actuators for some of the doors. The noise is caused by a failed actuator. You need to determine which of the two electronic actuators has failed and replace it. The actuators fail due to a cracked plastic gear on the output spindle that controls the door. The clicking you hear is the gear slipping inside the actuator.

Great information!!!!! Thank you.....

Reffering to the diagram; The noise seems to be coming from inbetween the blower motor and bottom case cover( from the back closest to the firewall). Could it be some type of internal linkage is causing the noise to reverberate from the back, maybe from the temp actuator?

Please edit your post if you have something to add rather than post consecutively & violate the rules of the forum. Thanks!

Not sure if this will help. Without a vehicle in front of me, I can't really picture how it all goes together. I did replace the heater core in my dad's '94 K2500, but that was over 10 years ago. You might have better luck on one of the fullsize forums.