There is nothing worse than sitting in a hot cab on a 35°C day while the AC blows warm air. A weak air conditioning system is not just uncomfortable — it reduces operator focus and productivity. Here are five checks to diagnose and fix poor AC performance fast.

1. Clean the Condenser Coils

The condenser sits in front of the radiator and collects dust, seeds, and mud. Blocked coils reduce heat exchange, and refrigerant cannot cool properly. Use compressed air or a gentle water spray from the back of the condenser to push debris forward. Never use a pressure washer directly on the fins — it bends them flat. Clean the condenser weekly in dusty conditions.

2. Check the Cabin Air Filter

A clogged cabin air filter restricts airflow across the evaporator. Even if the system is cold, weak air circulation makes the cab feel warm. Remove the filter (usually behind the cab grille or under the seat) and inspect it. If it is packed with dust, replace it. In extreme dust, change it every 250 hours instead of the standard 500. Never blow out a paper filter with compressed air — it damages the fibers and lets fine dust through.

3. Inspect the Compressor Belt

A loose or glazed belt causes the compressor to slip, reducing refrigerant flow. Press down on the belt midway between pulleys. Deflection should be 8–12mm. If it is looser, tighten it. Also look for cracks or fraying on the belt’s underside. A slipping belt often squeals when the AC is turned on — replace it immediately.

4. Run the System Monthly in Winter

Seals in the AC system rely on refrigerant oil to stay lubricated. During winter, when AC is rarely used, seals dry out and shrink, allowing refrigerant to leak. Run the AC for 10–15 minutes every month, even in cold weather. This circulates oil and keeps seals conditioned. Also, run the defrost mode — it uses the AC to dehumidify the cab, preventing fogging.

5. Watch for Refrigerant Leaks

If the AC blows only slightly cool, refrigerant is likely low. Look for oily residue around hose fittings, compressor joints, or the condenser — oil carries dye and is a sure sign of a leak. Have a technician test the system with an electronic leak detector. Recharging without fixing the leak wastes money and damages the environment.

Quick check: Start the engine, turn AC to max, and hold a thermometer at the vent for five minutes. A properly charged system should blow 6–10°C air. If it is warmer, one of these five checks is likely the problem.