TK 55676-19-IM-EN
85
A/C System Charging and APU Engine Start-up
Procedures
This is a multi-step procedure consisting of:
a. adding a partial refrigerant charge to the system
b. verifying APU engine has the proper amount of oil
c. bleeding air from the APU cooling system
d. bleeding air from the APU fuel lines
e. running the APU with the A/C operating and adjusting the engine rpm’s
f.
system fluids leak check
g. verifying alternator output voltage
h. adding a full refrigerant charge to the system
Adding Refrigerant Charge
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ntt:: Before starting the APU engine, oil and coolant levels must be checked to prevent damage to the engine
and the A/C system must have a partial charge of refrigerant added to prevent damage to the A/C
compressor. See “Bleeding the Coolant System” and “Bleeding the Fuel Lines” before adding a partial
refrigerant charge.
Special Tools Required
R134a Refrigerant
Scale
1. Connect refrigerant bottle to gauge manifold and place it on the scale.
2. Open refrigerant bottle valve for liquid and purge the charging line.
3. Keep the low pressure side valve of the gauge manifold closed. Open the high pressure side valve.
4. Add refrigerant until reaching 1 lb. 8 oz. of R-134a.
5. Close refrigerant bottle valve and the high side valve of the gauge manifold.
