What is done : System inspected for operating pressures, leaks, deterioration or damage to any hoses, seals or components. Drive belt tension checked. Chemical dye is run through the system for leaks and if found, hoses and seals replaced, then system is re-gassed. System recharged with refrigerant.

Frequency : Needs to be done once a year.

Reason: If the system runs out of gas, it can damage the compressor and lead to a huge repair bill.