Technician Instructions and
Information
Note: The following procedures involve servicing the air conditioning system.
Some of these service procedures are regulated by federal, and in some cases,
State and Local laws.
All regulated air conditioning service procedures must be performed by an EPA
certified technician, using approved equipment and complying with all, Federal,
State and Local Laws.
Charging the Air Conditioning System
These units can be damaged by over charging of refrigerant. The amount of
refrigerant the system can hold depends on circuit volume which is affected by
hose length. The most satisfactory method of charging the engine driven
compressor circuit is:
1. Connect a gauge manifold or charging machine to the compressor service
valves.
2. Connect the center hose of the gauge manifold to the manifold of an
evacuation pump or station.
3. Connect the hose from a drum of refrigerant to the manifold or evacuation
station. Make sure the valve on the drum is closed.
4. Open the valves on the gauge manifold and the evacuation station.
5. Start the vacuum pump and evacuate the system to 500 microns. After the
system reaches 500 microns, evacuate the system for an additional hour.
Note: If the system will not pull down to 500 microns, there is probably a leak in
the system or one of the evacuation hoses. Find and repair the leak.
6. After the additional hour of evacuation, close the valve at the evacuation
pump, stop the vacuum pump, and observe the reading on the vacuum
gauge for 5 minutes. The pressure should not exceed 2,000 microns.
Note: If pressure does exceed 2000 microns, repeat steps 4 and 5. This time if
the pressure exceeds 2000 microns within 5 minutes, a leak is present in the
system or one of the evacuation hoses. Find and repair the leak.
7. Open the vacuum valve at the vacuum pump or evacuation station, and
evacuate the system to 500 microns.
8. When the system reaches 500 microns, close the vacuum valve at the
evacuation station. The system is now ready to charge.
9. Close the low side valve on the manifold and leave the high side valve
open, open the valve on the refrigerant drum to deliver liquid.
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