Extreme weather events—such as prolonged heatwaves, heavy downpours, and severe blizzards—pose severe tests to the reliability of bus air conditioning systems. For bus operators, a malfunctioning air conditioner in extreme conditions not only affects passenger comfort but also disrupts urban public transport services. For manufacturers, optimizing bus air conditioning to withstand extreme weather has become a key focus of product R&D, especially for eco-friendly models like CO₂ air conditioning systems.
High-temperature heatwaves are among the most common challenges. During sustained temperatures above 40°C, traditional air conditioning units often suffer from compressor overheating or reduced cooling efficiency. To address this, we have made two key upgrades to our CO₂ air conditioning systems: first, we integrated a dual-cooling circuit design, which distributes heat load across two parallel circuits to prevent single-component overload; second, we adopted a high-temperature-resistant compressor motor, which can operate stably at ambient temperatures up to 50°C. These improvements have enabled our units to maintain 95% of their rated cooling capacity even after 8 hours of continuous operation in heatwaves, as verified in field tests in the Middle East.
Heavy downpours and flooding present risks of water ingress and short circuits. We have enhanced the waterproof performance of our CO₂ air conditioning units by upgrading the casing’s waterproof rating to IP67—preventing water penetration even in heavy rain with standing water on roads. Additionally, we redesigned the electrical connection ports with sealed, corrosion-resistant materials and added a water drainage system at the bottom of the unit to quickly remove accumulated rainwater. In a practical application in a Southeast Asian city prone to monsoons, these upgrades reduced rain-related air conditioning failures by 60% during the rainy season.
Severe blizzards and freezing temperatures bring challenges of ice accumulation and low-temperature startup. For cold regions, we optimized our CO₂ air conditioning systems with an automatic defrosting function: sensors detect ice buildup on the evaporator and activate a low-energy defrosting cycle, avoiding ice blockages that reduce heating efficiency. We also improved the system’s low-temperature startup performance by adding a preheating module for the refrigerant circuit, allowing the unit to start normally at temperatures as low as -30°C—critical for bus operations in northern Europe and high-latitude regions. Field data from a Nordic bus fleet showed that the upgraded units achieved a 98% startup success rate during winter blizzards.
Beyond hardware upgrades, we have also developed an extreme weather monitoring and response system. By connecting the air conditioning unit to a weather forecast API, the system can pre-adjust operating parameters before extreme weather hits—for example, increasing the cooling circuit’s redundancy ahead of a heatwave or activating the preheating module before a cold snap. This proactive approach further reduces the risk of malfunctions.
Looking ahead, as extreme weather events become more frequent due to climate change, we will continue to deepen R&D in materials science and intelligent control. For instance, we are exploring the use of self-heating composite materials for unit casings to prevent ice buildup, and developing AI-based adaptive algorithms that can adjust system parameters in real time based on changing weather conditions. By enhancing the reliability of CO₂ air conditioning systems in extreme weather, we aim to provide bus operators with more resilient solutions, ensuring the stability of urban public transport services regardless of environmental challenges.
