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I used the process of elimination, by swapping the actuators from left to right I knew it was the actuator so I check the motor and all resistors and capacitors in the circuit. All checked OK so I figured it must be the Op Amp because it was the only thing left on the board. You can download a datasheet for the L2722 to find what each pin on the IC does. I went so far as to check the voltage at each pin before replacing it. When viewed from the top of the IC pin 2 should have 12V, pin 4 0V, pin7 1.5V, pin5 4V, pins6&8 are tied together in the board this is the command voltage supplied by the HVAC controller (0-5V depending upon desired position), pins 1&3 are the outputs to the motor (0-9V) depending on voltage at pins 6&8. When you change the set temp on the HVAC controller the command voltage should change and the motor should spin.
Does anyone know if the Chev actuator replacement procedure calls for disconnect of the battery? Most shop manuals I've seen have Step 1 - disconnect battery for any procedure involving electrical connections. The last work I had done on my 2000 was replacement of both actuators a couple of months ago. Today I find that the negative battery terminal is on so tight that there's no getting it off. WD-40, vise-grips, etc. The dealer (located on Superstition Springs Drive in Mesa, AZ) insists that they didn't touch the battery. I go easy with that sort of stuff, so I know it wasn't me. After paying over $1250 for the actuator replacements, I would hope they'd fess up and make it right.
I had the same problem again with my actuator motor not working after replacing the OpAmp. It turns out that the problem was actually the motor. When I had originally tested the actuator components I took out the motor and connected it to a 12VDC power supply, it started out slow and then came up to full speed. I didn't think anything of it at the time but the last time it stopped working all I did was remove the motor and connected the leads to a 12V battery and it came up to full speed. I put the motor back in and it has been working fine for months.
Rather than spend for the OEM, I went to rockauto who had a cheaper one, cheaper by far and when I received it, it appeared to be the OEM one. Went in with no problem other than the hassel of accessing the area. Still working a year and a half later.
I'm currently installing the driver's side blend door actuator in my 98 C5. I uninstalled the old actuator but haven't cracked it open yet. As I was installing the new actuator I noticed that the blend door shaft was straight up and down @ 12 and 6 where as the new actuator's socket for the shaft was @ 9 and 3. Can I manually rotate the shaft to align it with the socket or is there something else I need to do first???
I just did the cracked gear fix on both air blend actuators even though only the passenger side was throwing the out of range code. The large gear on the passenger side was cracked exactly as shown previously in this thread. The driver side was starting to crack, so doing the fix on it made sense, especially since I had easy access to it. After the repair, I used the midrange ohm process to set the initial position of the blue gear. BTW, on my actuators (both factory) there is an indented notch in the housing (side that houses the gears) at mid travel as well as hard stops at the extremes. I also noticed that on the other housing half that there were raised marks for mid travel and well as what turned out to be the EXACT positions necessary to position the main gear to line up with the respective air blend shaft during installation. The actuator drive shaft on my units have notches slotted opposite each such that one of them points to the raised marks I mentioned. The side of the shaft that engages the air blend door shaft has a TAB that protrudes which would engage the hard limits if such excursion ever occurred (ie such as a broken air blend door shaft). That tab when aligned with the notch in the housing, is the center point of travel. These marks and tab along with knowing that the blue gear should read 4ohms more or less, made reassembly very easy with NO guess work.
On reinstallation, the drivers side actuator came up and initialized perfectly, but the passenger side was dead, totally dead. I swapped them to verify that it was indeed the actuator and sure enough, the suspect actuator was still dead (ie proved that the wiring and control signals from the AC controls were working properly).
I pulled it back apart and tested the motor in both directions with a 9V battery (it worked). I figured that the L2722 op amp must be fried. Still I thought I remembered that the passenger side had actually been working to some extent prior to my repairing the cracked gear.
I pulled the circuit board to ensure that there were NO cold solder joints on the bottom and then noticed that the blue gear "seemed" to have quite a lot of the yellow grease accumulated at the lower edge. On close inspection I could see that the grease was actually creeping onto the exposed copper slider elements of the potentiometer that is underneath the blue gear. I then used denatured alcohol and removed all the accumulated grease on the underneath side of the blue gear that I could with a cotton swab.
I reassembled the unit, set the blue gear for mid range (4.2ohms) and the drive gear for midrange as marked on the housing. I left the top gear out until I could determine which rotation was needed for installation, then I set the drive gear to that mark on the housing, installed the top gear, buttoned it up, and reinstalled it.
I really did NOT expect any miracles and in fact had already ordered a couple of L2722s from Digikey. I reconnected the battery, started the car, and fired up the AC. MUCH to my surprise and delight, BOTH actuators went through an initialization process and NO codes. So, what I have surmised is that even though I was able to read and adjust the blue gear resistance while disassembled, the grease MUST have caused an insulating barrier on the exposed copper wiper of the resistive element just below it after I reassembled as the ONLY thing I did was to carefully clean the ENTIRE circumference of the upper part of the potentiometer of ALL grease. I did notice that after cleaning it that the resistance measurement while setting the mid point was more stable than previous. FYI, the ONLY code it set after my initial gear fix was B0446, out of range, so the feedback potentiometer WAS producing some level of resistance but obviously, an INCORRECT resistance. As to why it prevented the actuator from working completely is a bit of a mystery.
David
Last edited by 2kblackbeauty; 08-04-2012 at 11:49 AM.
Reason: typo
I had hot air on the drivers side. Freon was good and I had a code for the passenger side actuator and the 441 code. I bought a new actuator. I ended up taking the dash off to get to the left actuator easier. The dash removal really is pretty easy. It beats the crap out of being upside down under the dash cussing and wasting time. It really isnt a fun job but doable.
Anyway I tried to turn my old actuator 2 teeth left and it didnt work. I put a new actuator in on the drivers side and worked perfect.
I wouldnt try the job with out one actuator. You can always take it back.
Well, I didn't think to fix my actuators, and it's too bad because I'm quite good with epoxy.
However, I did buy some Dorman 604-16 actuators from amazon for 38.99, plus 4.57 shipping, and took one apart to look inside and the gear is solid so hopefully it won't crack like the pressed in one does.
Also, one actuator gave an error at first, so I removed the cover, took a photo (that's when I saw the gear is one piece), and put it back in, and then it worked (I have no idea why) -could have been that slightly bent #6 pin, which I bent back straight...
Are you guys having to take out your instrument cluster to do this or can you get to these actuators without having to do that?
IPC does not have to come out. I gained access from below by removing the panel above the footbrake that houses the courtesy light, remove the Bose amp and remove the muffler like thing for the inside temp. sensor. As Zoidman said in another post, takes about 45 minutes.
Just a couple of notes from fixing my Driver's side actuator today:
1) There are 2 5.5mm bolts holding the actuator on, the top hole is just a locating pin.
2) The Bose module needs to be unplugged and removed, 2 7mm bolts secure it.
3) Removing the drivers seat is easily worth the 4 bolts and few minutes. I can't image getting in there with the seat in place.
I was all set to attempt to repair my actuator using epoxy when I noticed the same part is used in 1997-2004 Sierra / Silverados / Suburbans / Yukons. I dropped by my local scrap yard and picked 4 in about 10 minutes for a total of $9. In these trucks, the module is slightly left of center, right at the bottom of the dash and requires no disassembly to get to. I inspected each actuator and none were cracked. Part numbers on 2 of the 4 matched my C5 part perfectly.
I "clocked" the new actuator the same as the one removed from my C5 and now everything works perfectly.
Also notice that the hub is plastic. If these gears shrink like the old ones did, the hub should shrink right along with it, unlike the original actuator which had a metal hub that would actually expand rather than shrink.
IPC does not have to come out. I gained access from below by removing the panel above the footbrake that houses the courtesy light, remove the Bose amp and remove the muffler like thing for the inside temp. sensor. As Zoidman said in another post, takes about 45 minutes.
That's for the driver's side actuator. For the passenger side, the dash cover has to come off and the glove box has to come out.
After replacing my battery I started to have HVAC codes show up:
B0361 H
BO363 H
BO365 H
BO367 H
B0441 H C
B0446 H C
Some codes were marked H (history) but after resetting the codes they immediately come back.
Here are the symptoms I observed (These might help those who are trying to diagnose their problems):
After resetting the codes both the passenger and drivers side would default to full hot. The passenger side is unresponsive to any input on the temperature ****. The drivers side is also unresponsive to input on the temperature **** and stays full hot - until I get down to 60 then it switches to full cold and if I increase the temperature setting back up it stays full cold. Meanwhile the passenger side is still full hot.
As I decrease the temperature setting on the drivers side I can hear noises inside the dash - a plasticy clicking sound, even though the temperature remains the same coming out of the vents. The mode settings all work fine - I can select between upper, lower, defrost without issue – so I assume it is not an issue with the vacuum connection. After removing the drivers kickpanel I can just see the output shaft from the actuator. I put the key in and turn to ON. The fan is on and set to the lowest setting. I clear the HVAC codes and I observe the following:
First the actuator rotates clockwise roughly 90 degrees at a pretty fast rate - takes ~5 sec. It pauses breifly and then starts to step back counter clockwise rotating ~45 degrees in short bursts. This takes about 12 sec. Lastly it finishes the last 45 degrees counter clockwise at the same speed as when it moved clockwise. After all of this the same 6 HVAC codes have returned.
At this point Bill Curlee has given me feedback and thinks the actuator has broken teeth. The other possible issue is that the actuator needs to be reindexed. Thankfully this is the corvette forum and there is a wealth of information. I used the following up to this point in order to gain visual access to the drivers side actuator. This link also has a great report on how to reindex the drivers side actuator which I use later on.
Since I had issues with both drivers and passengers actuators I would need to remove the dash (only way to get to the passenger side actuator) and it would prove essential when attempting to repair the actuators since you need easy repeated access.
Finally I remove the drivers and passengers actuators, open them up and see: Attachment 48153240
Both have a cracked drive gears. In fact they were broken in the exact same fashion – one crack split wide open and one smaller crack. At this point my car is in pieces and I need two new actuators ($100+ each).
I decided instead of buying and waiting for new actuators to arrive, to repair the cracked actuators. It appears they broke due to a manufacturing defect (clearly the hole in the middle of the plastic gear that was pressed onto the metal output shaft is too small of a diameter – by a significant amount – and therefore eventually cracked). It is possible that the new ones would have the same issue. Therefore, I found the best solution was to fix the broken gear with a little epoxy.
The first step is to mark the position of the blue gear where it contacts the drive gear. It is also important to mark the corresponding position on the metal shaft. I also found it necessary to mark the outside of the case since cleaning the plastic drive gear and output shaft prior to epoxy could remove the marks I made: Attachment 48153241
If you mess up the marks it isn’t a huge deal since you will have to reindex anyway, but it could help you reindex quicker.
After removing the driver gear the first step is to slide the plastic gear off of the metal output shaft. In order to increase the inner diameter I rolled some sandpaper onto a pen and then rolled the gear on my palm. This ensures that the inner diameter is uniformly sanded. Attachment 48153242
I used 100 grit sandpaper since it cuts pretty fast and keeps the surface rough which is important for epoxy adhesion. After several test fits, I got it down to a diameter that snugly fit over the metal output shaft and the large crack was completely closed.
I cleaned both the inner diameter and the metal shaft with brake cleaner (any non residue cleaner would work as well), and mixed up some 5 minute epoxy. I applied the epoxy to the metal shaft (and used a toothpick to stuff some into the crack of the white drive gear) and then slid the gear back on while splitting the crack slightly open to avoid rubbing the epoxy off the output shaft. A spring clamp was used to hold the crack shut and keep the gear tight on the output shaft: Attachment 48153243
After letting the parts dry while I took a break, I put them back in the actuators and aligned them the best I could with the marks that I made. During the reassembly I also lightly coated the drive gear with some of the excess grease slung around inside the case. Don’t use too much or you might foul the sensor under the blue gear and have to clean it later: http://forums.corvetteforum.com/c5-t...-indexing.html
Now comes the tricky part. I put both back in the car (I only attached them with one screw since I needed to test them). Reconnected the battery, turned the key to ON, and .... nothing had changed. I still got the same exact 6 codes listed at the beginning of this saga. Not to worry though. In retrospect this isn’t unexpected since with the drive gear cracked, the blue (index) gear had moved several teeth out of position after a couple weeks of driving with this issue. So, I disconnected the battery, pulled the passenger side actuator (easier to get to) opened it up and pulled the drive gear and moved it two teeth relative to the blue gear. If you have questions about this look at the link given above that addresses how to reindex. Reassembled, and … I still got the same 6 codes. I repeated this process 4-5 times until all of the passenger side codes went away (3 driver side remained). Success! Now in order to make sure I wasn’t operating on the edge of an index issue, I advanced another 4-6 teeth or so till the codes came back and then I split the difference (went backwards 2-3 teeth) so I was right in the sweet spot. With the passenger blend door full closed (rotated counter clockwise) below is what my blue gear position looks like. The blend door I am referring to is the door that the actuator opens and closes. You can open and close this door by rotating the white shaft that the actuator attaches to when you install it in the car. This picture could very well be close to what you will need for the passenger side: Attachment 48153244
I repeated the same iterative process for the drivers side and after another 4-5 iterations I had no codes at all for the HVAC. After finding the sweet spot just as I did with the drivers side, here is the final tooth position for the blue gear (with the blend door closed – clockwise since this is the drivers side): Attachment 48153245
Hope this helps someone. Reindexing the blue gear relative to the drive gear takes some patience - at least in my case since mine was so far off - but eventually the codes did go away.
I would like to thank those who contributed to the other great write ups that helped me access and diagnose my (previously) broken actuators.
Absolutely a GREAT How-to!!!! Would make a great sticky, if one doesn't exist!
Last edited by grinder11; 11-11-2020 at 08:51 AM.
Reason: Spell and more info to add
Those actuators list for near three hundred dollars at a chevy dealer!!!!!!
From what I've read online, Dorman makes a good OEM replacement for less than half the price of OEM. That said, I'm going to try the repair route on mine, after reading this great How-To.
06-06-2011, 12:44 PM
