How a bus roof-top unit works
A roof-top unit houses the cooling coils, condenser coil, blowers and condenser fans in one weather-proof housing on the roof. A separate compressor on the engine pumps the refrigerant, and most units run on 24V.
Monthly checks
- Clean or replace the return-air filters.
- Check that every blower and condenser fan runs and is not noisy.
- Clear the condensate drains so water does not leak into the cabin.
- Look for oil marks on hoses and joints.
Before every summer
- Wash the condenser coil and check the evaporator coils for dirt and corrosion.
- Check the compressor clutch, belt and mountings.
- Have the pressures and refrigerant charge checked.
- Inspect the electrical connections, relays and wiring for corrosion.
Common problems
Weak cooling at the rear of the bus usually points to dirty coils, a failed blower or a low charge. Water dripping inside the cabin is almost always a blocked drain. Rameswar Cool Spares supplies compressors, coils, blowers, fans and hoses for bus AC systems – share the bus model and the unit’s label details for the right parts.