Search our Heavy Duty Truck Parts

Cab Air Conditioning Standards for Diagnosis and Repair

High A/C Costs

It is important to establish standards for Cab A/C maintenance because Cab A/C is one of the highest cost accessories on vehicles today. A study was conducted to identify high cost components and establish standards for Cab A/C diagnostic and repair procedure.

The results indicated that following these guidelines have:

  • lowered overall Cab A/C cost,
  • reduced Cab A/C breakdowns,
  • increased driver satisfaction,
  • reduced labor hours spent on non-scheduled Cab A/C repairs, and
  • created a pro-active approach to Cab A/C Preventive Maintenance.


Air Conditioning Technicians must successfully complete Cab Air Diagnostics training, follow trained procedures, and strictly adhere to standards when performing inspections, diagnostics, repairs and/or making adjustments.

Driver Benefits

Providing excellent Cab A/C maintenance and repairs increases vehicle utilization and driver confidence level. It also provides drivers the comfort they need on the highway and during rest periods.

The Fleet Owner benefits with:

  • improved available labor time,
  • planned, predictable cost,
  • reduced operating cost,
  • improved decision making, and
  • a pro-active workforce.

Cab A/C Maintenance Standards

  • Replacement parts must meet OEM specifications.
  • If system failure was the result of a mechanical failure or if any sign of system contamination is apparent, the system must be properly flushed and properly purged.
  • Contaminated refrigerants must never be reused in a A/C system.
  • When the refrigerant system has to be opened to ambient conditions, the drier/accumulator must be replaced.
  • Evacuate system and perform a vacuum test with a quality micron gauge.
  • Refrigerant systems should never be topped off to get the vehicle back on the road.
  • Each Technician working on Cab A/C systems must be Section 609 certified.
  • A/C systems generally should not be converted to another refrigerant.
  • The Dayco Krikit gauge I P/N U29 93865 (for V Belts), and Krikit II P/N U29 93866 (for multi-rib belts) are required tools used for checking and adjusting belt tension.
  • If a belt is found to be 20 lbs. or more under the recommended tension, replace the belt. Adjust new belts using Krikit gauges listed above.
  • Keep records of employees' Qualification/Certification to perform work on Cab A/C.
  • Service port caps must be reinstalled after A/C service is completed.
  • Refrigerant oil should be purchased in small containers.
  • Pressure washers should not be used to clean condenser fins.

Training and Reference Materials

  • Service Manual - A/C and Heating Systems for Heavy Duty Vehicles
    MEI 8890B
  • 2 Disc Set - A/C Procedures and A/C Classroom Training
    MEI 1000DVD
has been added to your cart.
View Cart Keep Shopping