| ID | Status | Date | Year | Make | Model | Transmission Type | A/C Controls | Public/Private |
|---|---|---|---|---|---|---|---|---|
| #13306 | Closed | 2005 | Chevrolet | 2500K Suburban Quadrasteer and very rare OEM from the factory Silverado front-end clip. | public |
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Problem: unable to change modes between defrost, vent and floor on automatic dual climate control system. Changed the mode actuator with new ACDelco part and part numbers matched old and new so feel good its the right part. Old mode actuator did not work consistently with 12v battery so believe it was defective. I was unable to get the backplate back on with the new actuator positioning. I therefore used 12v battery to move the new actuator to the position of the old actuator I had taken out. I did not overrev the actuator and took it directly from the factory setting to the setting mirroring the old actuator. I had to swing the white “anchor” gear towards the back of the truck to fit in the back plate. Installed back plate and then the mode actuator. I have done various recalibration from your site and others using fuse removal method and still not working. The white anchor gear swings nicely. Is this the only thing moving inside the mode damper box? Do I dare test the mode actuator with it uninstalled? Any advice appreciated. I just replaced with ACDelco the blower motor and module sinced died recently too after 14 years. Could I have installed the white gear anchor on the wrong side (should I try to swing to front of truck before installing backplate? Great forum you have here and happy to pay if you help with answer during the free period! |
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Here is a picture of the mode actuator under dash and how gears are meshed. Lighting not great under there. |
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Applying 12 volts to the actuator to move it may have damaged the actuator. Although there is 12 volts supplied to the actuator for powering the internal motor, the controls are limited to a 5 volt signal. The command voltages are either 0, 2.5 or 5 volts depending on the commanded position. With that said do you have a multimeter and backprobing terminals along with the physical ability to connect everything in such a tight location? Better yet do you have access to a scan tool that can communicate with the system? Not just an OBD2 code reader. |
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Thanks Sparky. I do not have access to a special meter. I do have an old timey multi-meter with needle gauges. I can reach the connection to check readings of the connector but don’t know what I am looking for to see if the signal is ok. My error in the info I provided. I applied 9v to the actuator, not 12v through a small transistor radio battery. I used a procedure on youtube from ACDelco technicians to do it. Hopefully it is not fried. Is there a good chance the gears are placed wrong? Or is that pretty idiot-proof? Everything I read says do NOT run the actuator uninstalled. Is it worth trying carefully running it uninstalled and stopping it before it hits the maximum ranges? Any ideas appreciated. Everything on this truck works, except the mode. |
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Sparky, I was able to get a code. B3770 Airflow Control 6 Feedback Circuit. It was in the history. We cleared it and it came back. There was also a Ull52 Loss Communication in history but it did not come back after clearing. |
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If you still have access to the scan tool you were using enter “live data” and look at the commanded versus actual counts for the mode door actuator. Also look at the command signal voltage to see if it is reading 0, 2.5 or 5 volts. Using that information, the attached diagram and the instructions in the following article you should be able to collect enough information so we can fix your truck. In case you have not already done this be sure to go to the passenger side junction block and disconnect and reconnect the harness connectors several times to clear any light corrosion. Be sure to inspect the connectors for signs of heavier corrosion or compressed terminals. The information in the following article related to actual wire positions may not match to your vehicle. Be sure to focus in on the actual wire colors as outlined in the attached wiring diagram. If an incorrect voltage is encountered you will need to follow up with further testing at the actuator and or the control head to narrow down the fault. Lastly be aware that once the data shows “stall” or a steady 2.5 volt reading and the code sets you can no longer do pinpoint testing. The ignition will need to be cycled off for a few seconds and then back on to “wake” the system back up. If you no longer have the scan tool to see this data then use a stop watch and limit your testing window to within 90 seconds of key on. |