Some Toyota Highlander owners report experiencing compressor failure, which often necessitates a complete AC system replacement due to the compressor's critical role in air conditioning. Common causes of AC problems include insufficient refrigerant, damaged control valves, dirty cabin air filters, refrigerant leaks, clogged condensers or evaporators, and faulty blower motors. Signs of compressor malfunction may manifest as strange or excessive grinding noises, indicating potential issues. To mitigate these problems, regular maintenance and inspection of the AC system, including the serpentine belt, are crucial. Additionally, owners should be aware that replacing the AC compressor and possibly the entire system can lead to significant costs, including labor and parts. Understanding these factors can help Toyota Highlander owners effectively address compressor issues and prevent future complications.

Some Toyota Highlander owners report experiencing serious transmission issues that can lead to complete failure and safety hazards if ignored. Common symptoms include strange noises, grinding or shaking during gear shifts, burning smells, and dashboard warning lights indicating transmission problems. Additionally, some owners have encountered unexpected complications during warranty transmission replacements, such as discovering cracks in the bell housing of the replacement transmission, resulting in extended dealership visits. Owners also report issues like the transmission not engaging reverse or prematurely upshifting, which may require specific components like the overdrive drum to be replaced. It is crucial for Highlander owners to address these transmission problems promptly to prevent further damage and ensure the vehicle's safety and reliability. Consulting a Toyota dealership or qualified mechanic for diagnosis and resolution is strongly advised if any transmission issues are suspected.