When I turn on my A/c, it blows cold, then hot and continues cold & hot in either auto or manual modes. I can hear a "moaning" sound from under the dash which cycles every 30 seconds or so. After researching all of the threads it sounds like the temp blend door actuator is constantly cycling. So far I have replaced the computerized climate control switch panel, cracked vacuum hoses and cycled the power. Any recommendations what to check next? If the actuator was faulty, would it randomly cycle as it does?

 

Sure sounds like the blend door actuator is at fault. The large gear inside likes to crack causing the actuator to go wacky.

 

With the key turned "on" engine not running and the A/C off the actuator still cycle's constantly. Still think the actuator is the culprit, if so i'll replace it. Thanks

 

Yes, that is what happens when the actuator goes bad. If you want to confirm, remove it and pop off the cover. It will be readily apparent.

 

I've got the same problem. All heat, all the time. When I look under the dash, seems to me like there are actually two "actuators" if that's what you want to call them. One directs WHERE the air blows; vents, floor, defroster, etc., and moves when I rotate the **** on the dash. This one has a long metal arm. Seems to work because I can direct my constant "heat" anywhere. What I can't do is turn that heat into fresh air/AC. There appears to be a second "actuator" behind the first one. Is this correct? Is this the one that may contain this cracked gear? Or does the one in front control both location AND temp?

Great site, BTW.

 

It's easy to be confused by the word "actuator". The actuator commonly discussed here refers to the temperature blend door actuator which is located on top of the heater box behind the glove box (awkward to get at) and is run by a small electric motor and has a nasty habit of breaking the plastic gear in the case because they get brittle with age. The symptom of that problem is the inability to control temperature but the vents work normally moving air when you change ranges (defrost, A/C, etc.) The actuators that move the doors that direct the air to the various vents are moved by vacuum applied to them. Manual system - directly controlled by the ****, automatic system - vacuum is controlled by solenoids. The actuators I believe you saw with the long metal arms are vent control ones.

 

I have same prob doesnt matter if vehicle is running,just as long as key is on,bout to change mine anyone have any tips on getting to the bolts for actuator i removed glove box but cant get to bolts closest to fire wall??

 

I just found out today at the dealership that the "temp actuator" is bad and, not wanting to pay their astronomical price to fix it we are going to fix it ourselves (just like we did with the hub bearings and so on). on the 2000 is it still accessable through the back of the glove box? If not how do I get to it?
Thanks guys for your help!
Amber

 

I don't know about the 2000, but I don't think they made any changes til 2002. I don't know what the big price problem is. Oh, they probably want to remove the dash. That's not necessary. I've got some tips for you if you do it yourself. Cheers.

 

We fixed the temp door actuator! yay! thanks to all your help! it was through the glove compartment, but then the heat stopped blowing....it now only blows cool or room temp air. all the fans are working, and all settings seem to work, it does get hotter a bit on defrost and defog settings, but not like it should. I tested it on a borrowed comp, and i tested the mix door or motor (i can't remember what it said now exactly, i just know it was the mix, and was right above the blower motor test), and it got really hot when i engaged that, just like it should do on its own, what does that mean, and what and how do I fix it????
also, knowing we probably had a bad thermostat, we changed it, and flushed out the radiator and reservoir (it had gunk in it) that was yesterday, and as of today a SES light came on 5 MIN AFTER I GOT A FULL TANK OF GAS and gave me code p0420 and I found another one that is b0161. HELP! I realize that p0420 has something to do with the cat. but what do you guys think it is given all that we did and the gas? and what the heck is b0161, i cant find that code listed anywhere???

(this blazer was my late mothers who passed in october, and I don't have a ton of money to keep it going, but I would like to fix it. Thanks to all you guys for helping!)

2000 Blazer LT v6 4.3ltr 2 wheel drive with auto climate air

Again, thanks guys for helping us girls out!