Re-Charging - DCS RF151 Service Manual

During production cycle, low side pressures will vary anywhere from 140 psi to 2 psi, depending at what point measurements are
taken. High side pressures can range from 481 psi to 25 psi also depending at what point measurements are taken.
In evaluating this system, the best point to determine if pressures are correct is at the end of the production cycle. This is the
point where there is a thick slab formed on the evaporator and the evaporator thermostat is near cut-out temperature. Using
Table B, convert temperature to a corresponding pressure.
If low side pressure is below pressure in Table B, check for the following:
1. A system leak
2. Capillary tube is restricted
3. Insufficient compressor (does not pump properly)
If low side pressure is above pressure in Table B, check for the following:
1. Restricted air flow
2. Dirty condenser coil
3. Leaking or energized hot gas valve
4. Overcharged system
5. Low side leak

2.7 re-charging

RE-CHARGING OF THE UNIT SHOULD BE DONE ONLY AFTER DIAGNOSING AND REPAIRING THE SYSTEM (see Section 2.1, Sealed
System Introduction). Be sure to flush the system with dirty nitrogen gas and evacuate to 50 microns before re-charging.
THE METHOD FOR RE-CHARGING THE UNIT IS BY WEIGHT USING VAPOR REFRIGERANT. Using manifold gage set-up, hook up
charge hoses to the access valve on the compressor's process tube. If any access valve is attached to the high side process tube,
remove it and then seal the tube by brazing before charging. Charge the unit to five oz. (0.313 lbs.) of R-134a.
After re-charging, check pressures. Refer to Table B for corresponding temperatures and pressures. If pressures or temperatures
are incorrect, check the sealed system, recover the charge, repair, evacuate, and then re-charge.
NOTE: It is not uncommon to have some condensation or a slight frost on the suction line. This may occur towards the end of the
production cycle. Liquid refrigerant is not getting into the compressor if the unit was charged properly. It is important that the
insulation remains on the suction line and the capillary tube together after any repair and that it is sealed at both ends. Repair any
rips or tears as needed with vinyl tape.
SEALEd SySTEM
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