BostonJoel

I have the dualzone option and have never had a problem with the AC. Today, in the 90 degree heat, the drivers side vents blow hot air and the passenger side vents blow ice cold air. Tried going back and foth between manual AC (snowflake) button and the automatic set for 65 degrees. Turned it off and on a dozen times. No help.
Could not find internet posting on this subject.
Can anybody give me a clue as to what might be wrong and how to fix it.
Thanks in advance.

Joel

John600rr

I'm going through pretty much the same thing. From what I have found on this forum, it usually comes down to the HVAC Actuator. Have you pulled your DTC codes? If not, it would be a good idea.

A search for B0361 will find a few posts on this topic.

I have found the following fixes:

1) Disconnect battery for 1 hour to let the actuator reset.
2) Add a little freon (don't see how this would affect our single evaporator A/C)
3) Replace the actuator.

I haven't personally tried any of these though. Good luck.

dpd

you're probably low on refridgerant[freon].could be a motor,but doubt it

BostonJoel

That is exactly what I found...two fault codes...the B0361 you mentioned and also B0441 Left actuator out of range....whatever that means....
I think I'll try the battery disconnect for an hour and, if that doesnt work, call the local non-dealer that fixes late model Corvettes.
Coincidentally I had the two cables off the battery today....at different times....wonder if that had anything to do with it???

Thanks for your help and advice.

John600rr

Yeah that may have done it. When the actuator was resetting (when you had the battery disconnected earlier) it may have gone out of range. Hopefully resetting it again will work for you.

It sure didn't for me. I disconnected my battery and it got a LOT hotter on the drivers side, still cold on the passenger. I'm pretty sure my actuator is shot.

I hope you have better luck than me!

Z06ufgrad2002

Most of the threads I've been reading recently with this problem have been solved by adding some freon to the system.
Pick up one of the setups from the local auto parts supplier with the gauge and freon. Recharge the system and see if that works.

mxw1

Add a little freon, this does cure it.

ALLEGRO

Forgive me in advance.

I don't see how adding R-134 is going to change the differnce between the two zones. Seems to me that if it is blowing cold on the driver's side that it "should" blow cold on the passenger side.

Someone help a stupid guy out !!!!!

ronwc

That's what I used to think. I tried reseting the "door" many times by pulling fuses, disconnecting the battery, resting codes, ect. Finally gave up and took it to the local Chevy dealer. First time I have been to a dealer in about 25 years. A few hours later they called saying my car was ready. Told me it was just freon and sure enough it was ice cold, both sides. I asked to talk to the guy that worked on it to get the full story. Basically here is what he told me - (this concise explaination was originally posted by dngrzne)

The way evaporator coils work is they are basically just that, a coil or tubing winding back and forth. When the system is properly charged, the whole coil is active, or cold. If the system is low on refrigerant only part of the coil will be active...maybe half, or maybe even less. The part of the coil where the refrigerant first enters is the first part that will get cold, and the only part if it is low. My understanding of the way the Vette's evaporator is arranged is that half of the coil does the driver side and the other half the passenger side, obviously the first part doing the passenger side. So if the system was low, only the passenger side would cool leaving the driver side warm.

JC in XTC5

Your explanation is incorrect. Also, the codes indicating an actuator out of range is clearly an indication of the air-mix door preventing cold air to one side of the dash.

The HVAC has one chamber above the blower fan with the heater core and another with the AC evaporator coils. The AC coils are no bigger than the size of a book. In a single zone system, the airflow temp is controlled by one single door that mixes the air from these two chambers, i.e. ranges from FULL COOL/NO HOTto NO COOL/FULL HOT to provide the desired air temperature.

In the dual-zone system, the air-mix door is split in two, one for drivers side and one for passenger, and they move independently. When the driver's side only blows hot air, that means that the airmix door on that side is stuck in NO COOL/FULL HEAT, i.e. only the air flowing through the heater coil is allowed to flow to the driver's side. The DIC codes confirm that.

So please don't just shout out "add freon" (which by the way, we don't use freon). That is not the usual cause for the dual zone split temp problem. Any dealer that says so probably added R134 but ALSO disconnected the battery which reset the actuator as the system does when power is disconnected, and runs through a recalibration routine - you just need to let it complete without any interruption. If that doesn't fix the problem, then the actuator motor is usually shot.

Bill Curlee

I agree with John!! Cant see how adding refrigerant will solve that issue!. The collar that drives the door is plastic. They are known to split and allow the shaft to slip on the shaft causing the out of range problem. If you reset the HVAC controller and the problem still exist, check the actuator.

BC

ronwc

[QUOTE=JC in XTC5]Your explanation is incorrect.

You can believe and handle it anyway you want, I am relating my experience and the expertise of an GM AC mechanic that works on the dual zone systems every day.

BostonJoel

Thanks to everybody for the advice and comments. This repair (other than disconnecting the battery for a while and reconnecting it) is beyond me. I have made arrangements with Atlanta Corvette/The Last Detail to fix the car. I will bring a print out of this whole thread. I will post the finding and results.


Joel

plaster

How do you check the actuator?

Bill Curlee

just remove the actuator and inspect it. check the collar and while its out and plugged in, see if it moves with the rotational input of the ****. Thats it,,,nothing fancy!

BC

ALLEGRO

Keep us posted after the fix

willig72

Hope some part of this will help.

B0361 Left Actuator Feedback Short to GND

Circuit Description
The HVAC Control Assembly receives a LH electric actuator position signal from the LH electric actuator. The LH electric actuator position sensor is a potentiometer that is tied to a 5 volt reference source through CKT 1791 and to ground through CKT 1798, both from the HVAC Control Assembly. The variable output from the potentiometer feeds back a position signal through CKT 733 to a pull-up resistor located in the HVAC Control Assembly. This signal is used to determine the necessary drive signal to the LH electric actuator motor to provide the proper air mix door position. This value is stored in the Keep Alive Memory (KAM) portion of the HVAC Control Assembly.

Conditions for Setting the DTC
· With the ignition in the ON position, CKT 733 is checked continuously.
· CKT 733 stays at or near 0 volts.

Action Taken When the DTC Sets
· The HVAC Control Assembly stores a DTC B0361 in memory.
· No driver warning message will be displayed for this DTC.

Conditions for Clearing the DTC
· Using the IPC clearing feature.
· Using a scan tool.
· A history DTC will clear after 50 consecutive ignition cycles if the conditions for the fault is no longer present.

Diagnostic Aids
· If the DTC is a history or an intermittent. Try to perform the tests shown while "wiggling" wiring and connectors, this can often cause the malfunction to appear.
· Visually inspect sensor connector and harness for damage, corrosion or water intrusion.
· Check for adequate terminal tension, mis-routed harness, rubbed through wire insulation, and broken wire inside insulation.
· Install a scan tool to the diagnostic link connector. Turn the ignition switch to the ON position. Select the OUTPUT CONTROL screen in HVAC special functions. Use the MISCELLANEOUS TEST screen to manually drive the LH electric actuator with the scan tool from fully open to fully closed. Monitor the LH MIX MTR POSITION FEEDBACK with the scan tool when this is done. A normal position feedback signal should range between 0-255 counts as the electric actuator is being moved.

Test Description
The numbers below refer to the step numbers on the diagnostic table:
2. This test checks for the 5 volt reference signal being sent from the HVAC Control Assembly along CKT 1791.
3. This step is determining if a short to battery voltage exists on CKT 1791.
4. This step is checking for the 5 volt reference signal being sent from the HVAC Control Assembly along CKT 733.
5. This step is checking for a short to ground in CKT 733.
6. This step will repair a short to ground in CKT 733.
7. Replace the HVAC Control Assembly.
8. This test checks for a short to ground in CKT 1791.
9. Repair the short to ground in CKT 1791.
10. This step is checking for continuity of CKT 1798.
11. Repair open in CKT 1798.
12. This step will replace the LH electric actuator.
13. Erase all DTCs and recheck for repair verification.
14. This step is determining if a short to battery voltage exists on CKT 1791 with the HVAC control head and the LH electric actuator disconnected.
15. Checks for an open in CKT 1791.
16. Repair the open in CKT 1791.
17. Repair the short to battery voltage in CKT 1791.
DTC B0361 - LH Electric Actuator Feedback Short (CJ2)


B0441 Left Actuator Out of Range

Circuit Description
The HVAC Control Assembly receives a LH electric actuator position signal from the LH electric actuator. The LH electric actuator position sensor is a potentiometer that is tied to a 5 volt reference source through CKT 1791 and to ground through CKT 1798, both from the HVAC Control Assembly. The variable output from the potentiometer feeds back a position signal through CKT 733 to a pull-up resistor located in the HVAC Control Assembly. This signal is used to determine the necessary drive signal to the LH electric actuator motor to provide the proper air mix door position. This value is stored in the Keep Alive Memory (KAM) portion of the HVAC Control Assembly.
When the HVAC Control Assembly is first connected to power (or the battery connection is established), the system will perform an initialization routine lasting approximately 60 seconds. During this routine, both RH and LH electric actuators will cycle full travel in both directions learning the end positions. Position feedback readings are sent back to the HVAC Control Assembly and compared to a range of acceptable end readings. If during initialization the position feedback readings are not within the acceptable range, a diagnostic code will be set. If the position feedback readings reach values of 0-5 counts or 250-255 counts, the HVAC Control Assembly will then interpret the reading as a "feedback-short" or "feedback-open" condition respectively. IMPORTANT: Feedback-short or feedback-open conditions can occur due to electric actuators being initialized while not being attached to the HVAC module case.

Conditions for Setting the DTC
· A damaged or bound up temperature door mechanism.
· Improper alignment of the temperature door after electric actuator replacement.
· The electric actuator has not been initialized after replacement.
· During initialization, the position feedback reading is not within an acceptable range.

Action Taken When the DTC Sets
· The HVAC Control Assembly stores a DTC B0441 in memory.
· No driver warning message will be displayed for this DTC.

Conditions for Clearing the DTC
· Using the IPC clearing feature.
· Using a scan tool.
· A history DTC will clear after 50 consecutive ignition cycles if the conditions for the fault is no longer present.

Diagnostic Aids
· If the DTC is a history or an intermittent. Try to perform the tests shown while "wiggling" wiring and connectors, this can often cause the malfunction to appear.
· Visually inspect sensor connector and harness for damage, corrosion or water intrusion.
· Check for adequate terminal tension, mis-routed harness, rubbed through wire insulation, and broken wire inside insulation.
· Install a scan tool to the diagnostic link connector. Turn the ignition switch to the ON position. Select the OUTPUT CONTROL screen in HVAC special functions. Use the MISCELLANEOUS TEST screen to manually drive the LH electric actuator with the scan tool from fully open to fully closed. Monitor the LH MIX MTR POSITION FEEDBACK with the scan tool when this is done. A normal position feedback signal should range between 0-255 counts as the electric actuator is being moved.

Test Description
The numbers below refer to the step numbers on the diagnostic table:
2. This test checks for the 5 volt reference signal being sent from the HVAC Control Assembly along CKT 1791.
3. This step is determining if a short to battery voltage exists on CKT 1791.
4. This step is checking for the 5 volt reference signal being sent from the HVAC Control Assembly along CKT 733.
5. This step is checking for a short to ground in CKT 733.
6. This step will repair a short to ground in CKT 733.
7. Replace the HVAC Control Assembly.
8. This step is checking for continuity of CKT 1798.
9. Repair the open or high resistance in CKT 1798.
10. This step will replace the LH electric actuator.
11. Erase all DTCs and recheck for repair verification.
12. This step is determining if a short to battery voltage exists on CKT 1791 with the HVAC Control Assembly and the LH electric actuator.
13. Checks for an open in CKT 1791.
14. Repair an open in CKT 1791.
15. Repair a short to battery voltage in CKT 1791.
DTC B0441 - Left Actuator Out of Range (CJ2)

YO-EL

First of all, if your system was simply low on refrigerant, you wouldn't be getting the actuator door codes..

Secondly, if only 1/2 the coil was getting filled with refrigerant, it would eventually ice up.....

Index the teeth by 2 on the actuator. There is an internal TSB on this.

brookman

I dont want to hijack this thread - but I have that code set - but my AC is ice cold and it is 106+ here. Where is the actuator located? I will probably not even mess with it until winter.

Bill Curlee

Well,, try this experiment. Turn the temperature to hot and see if you get heat on both sides!! The actuator can fail in either direction (hot or cold). If one side is hot and the other side is still cold or cooler than the hot side, you have proved that the actuator is stuck in the cold position or is out of range in the cold position.

Let us know how it turns out.

BC