Condensing units are often mounted on rails with flexible suction and liquid lines to permit sliding the condensing unit out of the bus body to aid in servicing.

Air-cooled condensers are used. Thermostatic expansion valve refrigerant controls are standard. Finned blower evaporators are also used.

The duct system usually runs between a false ceiling and the roof of the bus. The ducts, usually one on each side of the bus, have grilles at the passenger seats. The passengers may control the grille by opening and closing.

CERTIFICATION

The Environmental Protection Agency (EPA) has established as per the Clean Air Act (CAA) that all technicians who maintain or repair air-conditioning or refrigeration equipment or technicians who operate recycling, reclaiming, and recovery equipment must be certified. Certification is administered by organizations with certification programs that are approved by the EPA. It is important to understand, that as a Utilitiesman, if you are not certified, you cannot do any HVAC/R service that requires use or removal of refrigerants. Certification requirements are divided into two different areas - automotive air-conditioning and HVAC/R.

Automotive Air-Conditioning Certification

Automotive air conditioning is serviced or repaired more of tenth another types of air-conditioning systems. In today's world, automotive air-conditioning systems are heavily used as our society spends more and more time in their vehicles. Industry experts say that 25 percent of the R-12 purchased in the United States is used in automotive air conditioning. The fittings and hoses used in automotive air conditioning allow leakage to occur. Automotive air-conditioning service facilities or technicians are now changing (retrofitting) systems in vehicles to use refrigerant R-134a and removing CFC R-12 to meet new standards. From the EPA's standpoint, technicians must be meet the following requirements to be certified:

Be aware that venting refrigerant is illegal.

Understand why all the regulations are being created. Understand what is happening to the environment.

Have a working knowledge of SAE standards J-1989, J-1990, and J-1991.

Perform service in a safe manner without injuring personnel or damaging equipment. Areas that must be understood include venting, handling, transporting, and disposing of refrigerant.

Once these requirements are met through testing of the individual applicant, a certification card is issued.

Heating, Ventilating, Air Conditioning, and

Refrigeration Certification

Certification requirements to service standard types of air-conditioning systems are the same as for automotive air-conditioning certification. Unlike the automotive certification program, standard air-conditioning certification is divided into levels corresponding to the type of service the technician performs. There are four types of certification:

Type I - Servicing small appliances

Type II - Servicing high or very high-pressure appliances

Type III - Servicing or disposing of low-pressure appliances

Type IV (Universal) - Servicing all types of equipment

Individuals will be required to take a proctored, closed book test. These tests are offered by organizations approved by the EPA for the specific type of certification that the individual technician requires. Technicians can only work on air-conditioning systems that they have been certified for service.

Q33. The saturation temperature increases or decreases depending upon what factor?

Q34. What are the three basic types of automotive compressors?

Q35. A scotch-yoke compressor changes rotary motion into what type of motion?

Q36. Refrigerant can be put into a system when the service valve is back-seated. True /False

Q37. The POA valve, receiver-drier, expansion valve, and sight glass are combined in what type of device?

Q38. Service procedures for VIR systems are different than conventional automotive air-conditioning systems. True/False