Chevrolet HHR A/C failure and temperature gauge issue resolved by removing radiator cap when engine was cold on Chevrolet HHR

Some Chevrolet HHR owners report experiencing A/C failure and inaccurate temperature gauge readings, often linked to thermostat malfunctions that regulate coolant flow. Issues may arise when the engine temperature sensor or its wiring fails, causing the gauge to drop to zero and prompting the Engine Control Unit to shut down the A/C for protection. While disconnecting the battery to reset the ECU can sometimes alleviate A/C problems, it may not address the underlying issues. Additionally, the engine temperature sensor is a frequent point of failure, and replacing it is generally cost-effective. In some instances, the Engine Control Module may malfunction, leading to incorrect temperature readings that affect both the gauge and radiator fan operation. Although removing the radiator cap when the engine is cold might provide a temporary fix, it is crucial for owners to check and potentially replace the thermostat or engine temperature sensor for a long-term resolution.