zz28zz

My 2000 vette driver's side blend door actuator was generating bo441, bo361 and bo363 codes. Trouble started immediately after I replaced the batt.

Removed actuator and found large plastic gear split. Since I didn't have a lot of time, I picked up a Doorman replacement from O'Rielly's.

With new actuator plugged in but not installed, I get the same codes when it tries to initialize.

Thought maybe it has to be installed to initialize. Installed and still getting same errors. After 2 more attempts to init the actuator, I got it to init error-free. Next day it was blowing cold from all outlets.

When I got to work I checked codes and found the bo441 and bo363 codes are back again. Tried to reset codes abt 6 times, but continue to get the same codes. Drivers side is now cool but not cold. Pass side is cold. (I can live with cool for now)


I want to attempt to repair the original actuator. After I get the large gear epoxied, I need to figure out where to position the feedback pot and large output gear.

Anyone have a procedure on this?

Does the actuator need to be installed to get it to init w/o error codes?

Does a NEW actuator need to have the output gear offset 2 teeth CCW?

During the init sequence, does the actuator sense the blend door hitting its hard stops, or the actuator hitting it's hard stops, or does the feedback pot signal that the end of stroke is reached?

Thx for any help.

Bill Curlee

There suppose to be self calibrating. Try this:

Turn the HVAC control head to OFF. In the DIC, pull up the HVAC DTC and clear ALL of the. When you hit clear, you should hear the actuators actuate and cycle thru its/their range. Do this until the DTCs no longer return. Turn the system ON and test.

Bill

dmarkshark

IF none of this helps, try checking the freon level. If it is low on freon, it can cause some of these wierd issues you are asking about.

zz28zz

I've tried resetting the blend door error codes with the A/C off and at various fan speeds thinking the airflow (or lack of) might change the load on the actuator just enough to squeeze-by, but no joy..

I'll try a few more times to get a good initialization, but I'm getting worried the pass side actuator will bite the dust.


I doubt the freon level is the issue cause:
1. Issue started when battery was replaced.
2. When blend doors are initializing with A/C on, the drivers side vents get real cold when the blend door moves towards full cold position.
3. I have error codes for the drivers side actuator.

My workaround was to clear the codes and while blend door was moving to full cold position, shut off key and pull elec connector off the actuator. This would "lock" the blend door in the cold position. I was about to try this, but the actuator initialized w/o any errors (the one and only time).

I'd really like to get some clarification on exactly what the actuator wants to sense to be satisfied. I saw here on CF that it wants the counts to be 0-5 and 250-255 at each extreme. The feedback comes from the position pot, but that's an analog signal. Where does the A to D conversion take place? In the actuator or in the cntrl head? Can these counts be monitored with a scanner? Is there a spec for the pot voltage or resistance at each extreme?

I'm about ready to install a push-pull cable!!

dmarkshark

I like the push pull idea, sure would make it easier . LOL FYI , if the actuator is hooked up but not installed, it will throw the codes as per the service manual. This issue has sometimes been fixed by putting a 2001 + head unit in. Not sure if that will help, but there are some threads on the subject, and it has to do with the calibration issue from the head units.

mcgilles

I've been all over this kind of issue before!

first of all, to properly reset the actuators you need to pull the HVAC fuse for 60 seconds or more. resetting the code does not do it. and the HVAC computer will retain its values if you don't leave the power out for a while. start there, and try that a few times and see if the issue keeps coming back. mine did unfortunately. however until I was able to fix the problem I was able to get by by having a pair of needle nose in the car with me. I pulled the fuse when I got to work, and again when I got home. left it out until getting back in the car again. this allowed me to stay warm (this was over winter) for my 30 minute each way commute.

the range of 0-5 or 250-255 are actually the out of range readings. the HVAC computer sets codes if it goes through the initialization procedure and finds the end points within those ranges. normal operation it should never go beyong 5-250.

these problems can be fixed by turning the big white gear in the actuators relative to the pot gear. it takes most 2 teeth, mine required 1 tooth and it has been working ever since.

do not initialize the actuators while they are not connected to the door control shaft. this will cause them to go out of range and will set the codes. the shop manual warns you not to do this, just because its a waste of time.

the stock actuators used the doors physical limits to define their bounds. some new redesigned actuators it appears have stops molded into the case so newer ones might not use the door position to indicate the end of travel, that should improve things if you have one of the new ones since its door warpage which causes this issue. well that and broken gears! no broken gears on mine, I still have the original actuator which is now performing fine.

are we allowed to post links to....the other forum? I have a long thread with pictures and videos that might help you out.

oh and by the way, make sure you aren't rotating the driver's side temp **** too quickly, apparently that's a known issue that if you rotate it too fast it screws something up in the computer and causes it to go crazy. you don't want to rotate it from full cold to full warm in 3 seconds in other words.

zz28zz

Thx for the replies guys.
The more I think abt it, the more I think the actuator would have to define it's limits using the blend door hardstops. I assume this is why we see a lot of split plastic gears. Seems like limit switches would be the way to go here,, but I digress.


So, if it's the blend door warpage causing the actuator to need it's output gear re-indexed, it makes sense that a new actuator would need the same re-indexing.

I did pull the HVAC fuse for abt 5 mins a couple of times. Also pulled batt cable for abt 5 mins. Neither helped.

I'll have some time on Monday to tinker with this. Luckily, the drivers side is still blowing cool. BTW the temp control has been on 60 degs for days now!!

jgump

zz28zz

Oh yeah, mcgilles, not sure abt posting here in ref to other forums, but a link via a PM would be ok I would think. Send it on if you get a chance. The more I know abt these actuators, the better I feel abt tweaking on them.

NealB

see if this helps (not my post)

http://forums.corvetteforum.com/c5-t...actuators.html

cjcvette

Hey that looks familiar! While I was repairing my split gear, I lost it's position relative to the blue gear (thus a simple change in the blue gear by 1-2 teeth wouldn't work). If this happens, it is okay, you will just need to index the blue gear, reinstall, if it doesn't work, the pull the actuator, reindex, and repeat until it works. Also, I didn't have to pull the fuse to reset the codes, you can do that with the DIC.

In the post I tried to take pictures of how the blue gear is positioned relative to the large white gear for both the driver and passenger side, after I found the sweet spot.

mcgilles

sent. hope it helps!

zz28zz

Success!!
I repaired my cracked gear per the link above (THX cjcvette!!).

I got a little sloppy with the epoxy and got some on the shoulder of the large gear causing interference with the cover. Had to remove the excess epoxy with my dremel. After doing this epoxy repair, install cover and tighten screws with center gear removed. Check that the output shaft can be rotated. I couldn't rotate mine, so that's how I knew I needed to grind out the excess epoxy.

As for the feedback pot alignment, I used my ohmmeter and measured the resistance between the 2 pins on the elec connector that are by themselves (2 on one side and 3 on the other).
With meter set to "Kohms", I measured 0 to 8 kohms while spinning the feedback pot. Positioned it so it was reading 4 kohms and installed the large gear at its' midpoint in travel. This sets both their midpoints and apparently got them in sync.

When attempting to install the actuator, the blend door shaft wanted to be in the full cold position, so I had to open-up the actuator again, remove center gear, and reposition the large gear (without disengaging the teeth with the pot gear) to the "cold" position.

Installed the 2 mounting screws, connected elec connector, reset codes and walahhhh, got a good initialization on the first try.

Cycled desired temp from 60 to 90 a few times being careful to rotate **** very slowly (rumor is if it's turned too fast, it freaks out the controller).

Everything is working like a champ. Yeah!!

This time, to access the actuator, I only removed the lower panel down by the pedals and the "Bose box". I was able to replace the actuator with a minimum of cussing.
Took me abt 30 mins to remove the actuator, try to install the repaired one, re-open and move to full cold, install, clear codes and vacuum up the little bits of foam that fell out.

As a side note, I opened-up the Doorman actuator I bought at O'Riellys and noticed it has no feedback pot like the GM version does. Looks like there may be a wiper under the large gear, but I didn't want to start removing gears since I'll be returning it. If that is the case, I don't see a way to re-index it if needed. The Doorman actuator does have clips around the edges so it can be opened.
I took pics of it but can't figure out how to post them..

cjcvette

Glad to hear. Also thanks for posting the information regarding the use of the ohm meter to set the blue gear. I will put a link to this post in my thread for others to use.