Charging; Checking Compressor Efficiency - Daikin DCH048 Series Service Instructions Manual

SERVICING
LOW SIDE
GAUGE
AND VALVE
EVACUATION
3. If the vacuum pump is working properly, close the valve to
the vacuum thermocouple gauge and open the high and
low side valves to the high vacuum manifold set. With the
valve on the charging cylinder closed, open the manifold
valve to the cylinder.
4. Evacuate the system to at least 29 inches gauge before
opening valve to thermocouple vacuum gauge.
5. Continue to evacuate to a maximum of 250 microns.
Close valve to vacuum pump and watch rate of rise. If
vacuum does not rise above 1500 microns in three to five
minutes, system can be considered properly evacuated.
6. If thermocouple vacuum gauge continues to rise and
levels off at about 5000 microns, moisture and non-
condensables are still present. If gauge continues to rise
a leak is present. Repair and re-evacuate.
7. Close valve to thermocouple vacuum gauge and vacuum
pump. Shut off pump and prepare to charge.
S-103 CHARGING
WARNING
REFRIGERANT UNDER PRESSURE!
* Do not overcharge system with refrigerant.
* Do not operate unit in a vacuum or at negative
pressure.
Failure to follow proper procedures may cause
property damage, personal injury or death.
Only use refrigerant certified to AHRI standards. Used
refrigerant may cause compressor damage. The
manufacturer is not responsible for damage or the
need for repairs resulting from the use of unapproved
refrigerant types or used or recycled refrigerant. Most
portable machines cannot clean used refrigerant to
meet AHRI standards.
HIGH SIDE
GAUGE
AND VALVE
Operating the compressor with the suction valve
closed will cause serious compressor damage.
Charge the system with the exact amount of refrigerant.
Refer to the specification section or check the unit name-
plates for the correct refrigerant charge.
An inaccurately charged system will cause future prob-
lems.
1. Using a quality set of charging scales, weigh the proper
amount of refrigerant for the system. Allow liquid refriger-
ant only to enter the high side.
2. After the system will take all it will take, close the valve
on the high side of the charging manifold.
3. Start the system and charge the balance of the refrigerant
through the low side.
NOTE: R410A should be drawn out of the storage container
or drum in liquid form due to its fractionation properties, but
should be "Flashed" to its gas state before entering the
system. There are commercially available restriction devices
that fit into the system charging hose set to accomplish this.
DO NOT charge liquid R410A into the compressor.
4. With the system still running, close the valve on the
charging cylinder. At this time, you may still have some
liquid refrigerant in the charging cylinder hose and will
definitely have liquid in the liquid hose. Reseat the liquid
line core. Slowly open the high side manifold valve and
transfer the liquid refrigerant from the liquid line hose and
charging cylinder hose into the suction service valve port.
CAREFUL: Watch so that liquid refrigerant does not
enter the compressor.
Final Charge Adjustment
The outdoor temperature must be 60°F or higher. Set the
room thermostat to COOL, fan switch to AUTO, and set the
temperature control well below room temperature.
After system has stabilized per startup instructions, com-
pare the operating pressures and outdoor unit amp draw to
the numbers listed in the spec sheet manual. If pressures
and amp draw are too low, add charge. If pressures and amp
draw are too high, remove charge. Check subcooling and
superheat as detailed in the following section.
5. With the system still running, remove hose and reinstall
both valve caps.
6. Check system for leaks.
Due to their design, Scroll compressors are inherently more
tolerant of liquid refrigerant.
NOTE: Even though the compressor section of a Scroll
compressor is more tolerant of liquid refrigerant, continued
floodback or flooded start conditions may wash oil from the
bearing surfaces causing premature bearing failure.S-104

CHECKING COMPRESSOR EFFICIENCY

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