I just became a member due to the great information I have found in helping me with repairs to my 98 Blazer. Recently I have been searching for the reason why my A/C is only blowing hot air, after reading many post I decided to look at the blend door actuator. Found the gear was broke, I have now gone to 3 different auto parts stores and the GMC dealership and can not find one that matches to mine.

The actuator was found behind the glove box, like stated in many posts on this forum. My actuator is matches all the other actuators mounting hole locations, but where it mounts onto the blend door shaft is the first problem. All the actuators I have looked at have a bushing that protrudes outside of the housing. One opening a small I.D. bore the other almost "T" shaped. Mine has a straight hole, guessing around 3/4" or so, and smooth. That is slid over the blend door shaft which is knurled or spline. The second issue is my plug in for my actuator has 6 pins and all other that I have looked at seem to have less and the missing pin is in different spots depending on which actuator I looked at.

I'm to the end of the line no one else seems to be able to help me, any information anyone has on what I should be looking for or doing different please let me know. I have a 4 year old that hates the windows down on the 20min drive home and its really warm out now.

 

Do you have manual climate controls or automatic? I believe the actuator may be different depending on which system you have.

 

It is the actuator, Look at the wire loom connector how many pin connectors does it have? Automatic is a 5 pin (which is yours) and the 4 pins are manual. They cost anywhere from 85$ to 145$ on ebay or most parts stores. Without knowledge of the year, model and make its hard to help you further.

you can manually turn the blend door to the cold side, at least have ventilation in the meantime.

 

I have a 98 chevy blazer LS series, looks like my wiring harness for the actuator has only three wires going into the plug. My heat/ac works off of three turn *****, one for temp another for fan speed and then for the third for ac and vent selection. I've looked at both manual and automatic style. Neither had the hole size that would fit the blend door shaft, unless that bushing is removable? Any thoughts

 

I just happen to have a blend door actuator sitting here next to my chair. I took a look at it and I don't believe the bushing is removable.

You definitely have manual controls. The actuator should have four pins and there should be four wires going to the plug. Your actuator doesn't match what I know about the actuators that I've seen. It's very strange that it has six pins instead of four.

Can you check the RPO Code for your climate control system? It should be on the RPO Code list in the glove box. In 1998 the code for manual controls should have been C60. The code for automatic controls should have been C68. Let us know which code you have. That may give us a clue as to what's going on here.

 

Looks like it's a C60, so says the label on the glove box.

 

According to the RPO code you should have manual climate controls with a four-pin actuator. I'm not familiar with the actuator in the picture you posted. I've never seen one like that before. I don't have any other specific ideas.

Have you tried looking for a part number and searching for it on RockAuto.com?

 

You know I'm reading up on this subject alot lately for obvious reasons and I'm looking at the doorman replacement for my auto climate system part 604-106 which is selling for around $100. I briefly found it around for like $60 but they all snatched up and it got me thinking... the manual replacement 604-100 I can find for around $30+ and from dormans photos it looks like it could be the same gear inside... Anyone have any reservations or cautions before i buy the manual unit and try to transplant the broken drive gear?

 

I've heard of people taking the actuators apart and swapping the broken gears. I don't recall specifically if they were successful. Do some searching on the Forum and see what you can find.

 

if after you figure out which blend door actuator you need to replace manual or auto, you may end up with a very common problem were the blend door is cycling and unable to find it's limits. This problem has driven me crazy for six months since i changed the battery out. All the threads here and on most other sites give the basic calibration procedure. this says to remove the dro bat fuse for 20 seconds, with the power off, then put it back and turn the key to the on position for 40 secs. all good except it is missing a very key step.

I have finnally nailed the problem down thru an honest Chevy mechanic. "this is a known problem throughout many of the chevy product lines. in order to fix it the five volt signal needs to be jumped to one of the pins on the connector to the unit can first find it center positon. The aforementioned cal procedure can only find the limits but without the center position being first calibrated the DRO bat fuse removal procedure cannot work". This is exactly what i see happening. Chevy does have procedure for calibrating the unit about $100.00. but not to fret. there is a tsb 150-9645 that explains which pins to jump. I will post it as soon as i can. i did the procedure last night and it work!

Of course this is a real design issue that chevy will not take responsibility for and therefore they expect the owner to pay a 100.00 fee. Change a battery and then pay $100.00 to have heat and air conditioning again.

go figure.