B0441 and B0361 HVAC codes
Hot air blowing out one or more vents is a common problem with 1997 Ė 2000 Corvette C5ís. If you feel like you are being baked in your car, and your passenger is nice and cool, more than likely you have an incorrectly calibrated HVAC actuator. The best description I have found isnít from any C5 TSB, but from a Buick TSB :
Some customers may comment on a temperature variation between the left and right hand ducts. Typical concerns may include that the right side of the vehicle cools down but the left stays warm or the opposite. This condition is sometimes associated by the customer with a recent service visit for other non-related repairs. The codes, DTC B0361 or B0441, may be present but will not illuminate a telltale lamp.
The HVAC controller unit and the TEMP door actuator motors rely on a feedback system that supplies the controller with count values in order to accurately adjust the air temperature. When battery power is interrupted to the HVAC controller, the current actuator position values are lost. When power is restored, the controller will perform a "sweep test" of the doors from full cold to full hot and record the end values for reference. Over time, the TEMP doors may develop some flexing when run to their extremes. This flexing allows the count values to run out of range (beyond 0-255) and results in DTC code B0361 or B0441 to set.
A revised HVAC controller has been released with new programming that allows for a wider tolerance in the expected range of the TEMP door. Replace the controller.
My experience for the last 2 years has been this. About 50% of the time, when
power to the HVAC system was interrupted, or a PCM reboot occurred, I would
encounter the above problem. For me it was whenever I disconnected the battery
for service, or when I reprogrammed my PCM using EFILive. As part of the
reprogramming process, EFILive would perform a PCM reboot. It was at that point
the HVAC system would go through the HVAC door recalibration as described above.
About half the time it would fail, throwing the B0361 and B0441 codes. Removing
the battery cable most the time would cure it, until next time I reprogrammed
the PCM, or disconnected the battery for any reason. It might be worthwhile
disconnecting your battery for a few minutes. While it will probably come back
at some point, this *might* be a permanent fix for your situation. More than
likely though it will come back at some point down the road.
It is my understanding that this can be cured one of two ways. The first is the simplest, but most expensive way. A newer 2001+ HVAC head unit will supposedly cure it. As shown above, Buick also has a similar fix. The second (and documented below) is to reindex the door in question. The document below is ONLY for the driver side Actuator. This seems to be the most common one to fail. If you are not getting codes B0441 or B0361, stop reading! Itís either the right Actuator, or possibly some other HVAC issue.
Important : If you are getting B0441 and B0361, adding Freon will NOT fix your problem!!!! I have seen several recommendations to add Freon as a fix. These codes have NOTHING at all to do with Freon!!!
- Before you go any further, confirm that you have a HVAC DTC set.
- Turn the ignition to ON (no need to start the car).
- Press and hold down Options, and hit Fuel 4 times. This will put you into diagnostic mode.
- The computer will now scroll through all the modules, showing the error codes. Once it is done it will display "No More Codes" At any time you can scroll up and down to see each code by using the Trip and the Options buttons. Scroll to the component that has the code and press the Gauges button to view the code(s) numbers. To scroll through these code numbers, use the Trip and Options button again. Hold "Reset" to clear any codes. You can delete one code at time or all codes in any component.
Using the above steps, you can confirm that there are indeed HVAC codes set.
If you have never done the above, now would be a good time to make note of any
other codes you might have.
Before you go any further, scroll until you get the HVAC using the Trip or Option button. With 99-HVAC highlighted, press and hold clear. You should hear the HVAC doors going through their recalibration. Wait about 15 seconds, and go back through all the codes. If HVAC is now clear, you might want to hold off on going through this document. Chances are though the B0441 and B0361 codes came right back. If so, I would recommend the recalibration of the drivers side actuator.
|Pictured to the left are the HVAC codes you should see. As stated above, stop if you do not see these codes!|
|There are 2 ways to get to the
drivers side actuator. This is NOT the method documented in the GM
service manual, which recommends pulling the instrument cluster. Itís
possible the GM method might be easier. I went this route. While itís
possible to Ďget toí the actuator with only removing the kick panel
cover (the one with the light), you wonít be able to remove it with the
HVAC sensor baffle in place. This requires removing the lower dash pad,
basically in the same manner as you would do the Column Lock Bypass.
Once that panel is removed, you can move the sensor airtube out just
enough to remove the baffle. Since I have only done this once, and hope
to never do it again, I canít say for sure if you can do this with only
removing the one kick panel. It would be worth a shot to try this first
as that panel has to come off regardless.
Before you start, disconnect the battery.
Center Console Disassembly
|Remove the 2 10mm nuts.|
|Gently pry open the traction control cover from the rear facing side. Disconnect harness and set assemble aside.|
|Remove the 2 screws in the cigarette
lighter area. You will have to remove the ashtray to get to the second
Slide the back portion of the console back, and then lift up and over the studs so you can slide it back another inch or so. D
This will give you room to work around the ignition and temp sensor area.
Slide the front portion of the console back console, while releasing the clips surrounding the radio/HVAC. Once again, lift up and over the studs to give you that extra inch of working space.
Knee Panel Removal
|See LS1HOWTO.COM link on the left for the best way to remove the kick panel.||See this page for better pictures and
documentation on how to remove the knee panel :
From the bottom, pull down and back on the kick panel cover. It's in
Remove the kick panel cover under the dash. 2 screws and a retainer.
|While this step isn't needed, it really
helps open up the work area under the dash. Skip it for now if you
Remove the metal/foam knee brace. Itís held in by 4 screws. Be careful with the HVAC sensor!
You will need to remove 2 wiring harnesses that will be attached to this brace.
|There is a air tube that connects to the
opening where the HVAC sensor is located. You will need to move that
whole tube towards the back of the car about an inch. It is
'locked' in place at the front of the tube, so you will need some small
needle nose pliers to release it.
You can now remove the baffle. Shown is the GM drawing of this tube since I didnít get a good picture of it.
|The actuator is behind the radio, on the
side of the airbox.
Itís the black box above that has the barcode on it. There will be 2 small screws holding it in place.
I had to remove 1 screw from the BOSE unit - The metal box with BOSE written on it, not the radio.
|The actuator removed!|
|CAREFULLY remove the 4 screws and cover.
Gently pry the cover off slowly as not to disturb the current gear positions.
|Mark the position of the gears,
particularly the drive gear, and the small blue gear attached to the
Pull the center gear out top-most (no need to mark it) and pull the drive gear up. Rotate the big drive gear counter-clockwise 2 teeth. Disclaimer Ė After seeing someone else rotate this gear counter-clockwise and it worked, I also tried the same thing. It also worked for me. I make no guarantees that counter-clockwise is the correct direction for your situation.
Pictured is the mark I made on the big drive gear, and the blue sensor gear.
|At this point, I would
recommend ONLY reinstalling the actuator. Reconnect the battery and see
if the codes come back. I would scroll through to 99-HVAC on the DIC
and press and hold the RESET button to force a reset of the HVAC
system. See if that makes the code come back. Turn the HVAC knobs to
both extremes (hot and cold) and check the codes again.
I even went so far as to disconnect the battery for a few minutes, a few additional times to confirm that the codes didnít come backÖsomething that was a crap shoot before I reindexed the actuator. If you are unable to get the codes to come back, you *should* be good to go ahead and put everything back together.
Disclaimer : This is a VERY rough draft, and I claim no responsibility for any damage or problems you may run encounter. In other words, buyer beware!