2001 Cadillac DeVille A/C Failure: Trouble Codes P1540, B0429, B1327 - Solutions & Orifice Tube Location
I own a 2001 Cadillac DeVille with persistent air conditioning issues indicated by trouble codes P1540, B0429, and B1327. The temperature is currently high outside, making the AC performance critical. I'm seeking reliable advice on diagnosing and fixing these codes—especially P1540, which relates to the air conditioning system's high pressure. Can anyone confirm whether the HVAC actuator (B0429) is likely located in the rear cabin? Does this model have a filter, and if so, where is it situated? Any guidance on how to safely check refrigerant pressure or replace components would be greatly appreciated. Thanks in advance—JohnB231
Code B0429 relates to an HVAC actuator—likely the rear air door actuator. I’ll verify this with a physical inspection if time permits. Code B1327 typically indicates low battery voltage or charging system below 9 volts, which should be checked first. For P154-0: This points to high AC pressure in the system. Use an AC gauge set to measure actual pressure—this is essential for diagnosis. If it's a sensor issue, simply unscrew it—the component sits on a Schrader valve and won’t leak refrigerant when removed. Reference image: http://parts.nalleygmc.com/images/parts/09-037.JPG In the diagram, the switch is labeled #27. The orifice tube is located at #2—please do not replace it without a full system diagnosis to avoid overcharging or refrigerant loss.