No Heater or AC control or defaults to defrost–GM Trucks
Owners of some GM Truck and some SUV owners may experience a problem where they cannot control the heating, ventilation and A/C system. They may also find that the system always defaults to the DEFROST mode. The following trouble codes may be stored in memory: B0229-Recirculation Actuator, B0414- Left Air Temperature Actuator, B0424 Right Air Temperature Actuator, or B3770 Mode Actuator Cause
GM reports that the problem may be found in the HVAC actuator harness contacting a sharp edge of the instrument panel (like they couldn’t have seen that coming during production). If that happens, it creates a rub through and grounding of the actuator control and feedback circuits. This problem may affect 2003-05 Cadillac Escalade, Escalade ESV, Escalade EXT, Chevrolet Avalanche, Silverado, Suburban, Tahoe, and GMC Sierra, Yukon, and Yukon XL.
To fix the problem, find the HVAC harness rubbing point behind the instrument panel. This is on the left side of the dash, behind the instrument panel compartment door. Open the door and locate the harness to inspect it. Repair any damaged wires. Install protective sleeving around the harness. Install friction tape to cover the sharp edges of the instrument panel brace.
Clear the trouble codes.
For more information on this repair or any others for your vehicle, buy an online subscription to either Alldatadiy.com or eautorepair.net. Click on this link to compare the two services: Compare Alldata and Eautorepair.
If you just need information for a single repair and want to save money,eautorepair offers a lower price 1-week subscription for only $11.99. Or, if you’ll be working on this vehicle in the future, you can buy a 1-year subscription (Alldatadiy.com for $26.99, or eautorepair.net $29.99)
© 2007 Rick Muscoplat
Alldatadiy.com
eautorepair.net
Both Alldata and Eautorepair offer professional grade shop manuals at a price you can afford. Check them out!.
Hover your mouse over the REPAIR ARTICLES tab at the top of the page. The click on DIAGNOSTICS to search by SYMPTOM, TROUBLE CODE, or read TECH TIPS on how to diagnose a problem
Click on MAKE an MODEL to see all the articles I’ve written for your vehicle
Click on REPAIR TOPICS to read individual articles written for specific automotive systems
If you’ve had your car scanned and know the trouble code go to TROUBLE CODES
Here are some quick links to speed up your research
Click on the link below for speedy navigation:
ABS issues, how to bleed ABS brakes
Alternator issues or how to test
Belt diagram or serpentine belt issues
Brakes, brake issues, what kind of brake parts to buy, ABS issues
Car Alarms or Antitheft systems
Cooling system, Water pump, What type of coolant to use
Firing order, cylinder layout, finding #1 cylinder
Oxygen sensors, How they work, How to change, How to test
Window issues, power window motor, replace window regulator, glass adhesive
i have a 97 chev k1500, V6. The blower fan does not work. The heater/Air Cond/defrost control unit seems to work as I can feel some heat and the windshield slowly defrosts, but the fan does not run. Any help you could provide would be appreciated
Power flows from fuse #12 (25A) through the fan speed switch and then to the blower motor resistor. Then it goes to the blower motor on the purple wire. The ground for the blower motor is the black wire. Disconnect the electrical connector and use a multi-meter to see if you have power on the purple wire. If so, check the black wire for good ground. If you have good power and ground, you’ve got a dead blower motor. You can also try supplying battery voltage to the feed terminal on the motor and ground to the other terminal.
If you don’t have power to the motor, you’ll have to work backwards towards the switch and control head.
Best to invest in a wiring diagram for this job.