I have a '98 Blazer, 4 door 2 wheel drive. It is an LT and it has the electronic climate control. The a/c compressor is shot, the blower motor doesn't work, AND it will has really hot air coming out of the vents (which sucks when it is already pushing 90 outside!). I tried the reset by pulling the rdo batt fuse for a minute then replacing it and turning the key to "run" position for at least one minute. The next day I noticed a noise coming from dash which seems to be the sound of the actuator attempting to work. The sound just keeps on though, it just does it over and over and over again!! It is not very loud so I can ignore it for now. Sadly I can buy a new a/c compressor for less than that stupid little electronic actuator!! Can someone PLEASE tell me where the actuator is located? I had read that it was behind the glove box, but I am not taking anything apart until I know for sure!! Thanks for the help!!!

 

Check out this thread:

https://blazerforum.com/forum/2nd-ge...e-69344/page2/

If you go back to the first page of the thread, there is a schematic you can download that shows which actuators do what.

 

So I checked out behind the glove box. Looking at the 2 actuators that can be seen behind the glove box, both seem to be operating properly. Although I am a bit confused. Both actuators I see behind the glove box appear to be vacuum controlled. The blend door actuator is electric isn't it? All I know for sure is the 2 behind the glove box are working. I pulled the blower motor out and used some compressed air to clean it out, (I also pulled a few HUNDRED leaves out of the compartment from the blower motor to the heater core!) and I used some dry lubricant in an attempt to get it working. It did not work. So if both actuators behind the glove box work, does that definitely rule out a bad blend door actuator? Why is there hot air seeping out of the vent system at all times? I know for sure that the a/c compressor is not good, will that mean that until I fix the compressor there will just be hot air present? Will replacing the blower motor possibly fix the issue? PLEASE HELP!!!!!

 

The information you seek is only a search away:
2nd Gen Blend Door Actuator Replacement
2nd Gen Blend Door Actuator Replacement (alternate method)

Found in the Tech Article (DIY) section.

 

I now know where the actuator is, and how to replace it. My issue is that it is a hundred bucks for that stupid electronic actuator! I am trying to make 100% sure it needs one before I go through the headache of changing it out, and paying for a new one. There is a round vacuum actuator that moves when I turn the temp ****.

 

now slightly off the subject im have the same problem but i went to change my a/c control module and the used one i bought didnt work so i put the old one back in and now my blower wont turn on. what would cause that and how can i fix it. i checked fuses all good but i heard there was a fusible link thats on the power line for the blower where would that be at.

 

OK - here is my scenario.

98 4 dr 4wd, climate control.

Wife complained about heat always on and 'making noise'.

When the ignition is on a movement is heard down under the dash, sure sounds like a the damper door. It cycles about every 5 seconds, sounds like it is full opening and closing. I didn't check the air temp.

I pull out the actuator and sure enough it has the cracked gear. I rotated the gear so that the 'good' portion is what is being used and reassemble.

The cycling noise went away but now there is no heat. I removed the actuator and when I popped it off the shaft came out of the gear splines and remained on the damper shaft. With the ignition on I could see the gears turning in the hot direction, it just constantly ran.

When I manually manipulate the damper I get nice hot air.

I put the actuator together and connected it electrically. I left it dangling so I could observe it. With heat settings on full the unit drive to the hot position and stopped (due to the mechanical stops). Turning on A/C, setting temp full cold did not cause it to budge, it remained on the hot position.

So, anyone have any ideas? First, is there any type of force feedback or positioning sensing with the actuator - or does it simply drive in one direction constantly to the mechanical stops?

is it possible there is more at fault with the actuator than the cracked gear?

Thanks as always.

 

you must have found this thread by using the search feature. good job.

well i would say that your motor might be on the fritz. it seems that its only working in one direction right? the motor shouldnt keep moving even its not hooked up to anything. at least i dont think so. think about this, or try it, put the temp **** in the middle to 74 and see what the motor does. keep the fan on low. there are sensors in the vents to figure out how hot or cold the air thats coming out is. so if you have the fan on high, the motor wont stop turning until the sensors start to get warm or cold air. all depending on which it needs to make the cabin the temp that you desire. there are preset settings with all of that. if you move the temp **** to 74 it will put the blend door in a certain position and the adjust from there. so keep the fan on LOW, move the temp **** but keep it in the actual temp range. if you go to the blue or red dash, it puts the blend door all the way to the one side.

keep us posted

 

Thanks for posting Twip. I appreciate the help, you and Swartllk have helped me several times over the years.

I wasn't able to do as you suggested - I will try that soon. What I did do was find that there is a reset procedure:

https://blazerforum.com/forum/2nd-ge...33/#post158673

I took the actuator apart and set it up into the full heat position. I then hooked it up to the harness and did the reset procedure. Lo and behold, it started the cycling behavior again. It would go to just short of halfway to full cold, then to full hot, sit about 5 seconds, and repeat. No stopping it.

Swartlkk indicates that there is some sort of resolver in play. There is absolutely nothing at all in the actuator. The only thing I can think of is that it measure current maybe somewhere?

Anyway, with it all apart, it just runs constantly in the hot direction. If there is indeed some sort of crude resolver for position info, maybe my cracked gear is enlarged enough to bind up and confuse it?

Thanks again.

 

Correction - there is indeed feedback. The blue gear sits on a pot, I didn't even notice it.

Knowing this now I will try some more homing experiments.