SERVICING
50
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.
CAUTION
Use refrigerant certified to AHRI standards. Used
refrigerant may cause compressor damage and is not
covered by the warranty. Most portable machines
cannot clean used refrigerant to meet AHRI Standards.
CAUTION
Damage to the unit caused by operating the compressor
with the suction valve closed is not covered under the
warranty and may cause serious compressor damage.
Charge the system with the exact amount of refrigerant.
See the Installation Manual for the correct refrigerant charge.
An inaccurately charged system will cause future problems.
1. When using an ambient compensated calibrated charging cyl-
inder, allow liquid refrigerant only to enter the high side.
2. Once the system stops taking refrigerant, 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 sys-
tem 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 refriger-
ant in the charging cylinder hose and will definitely have liq-
uid in the liquid hose. Reseat the liquid line core. Slowly open
the high side manifold valve and transfer the liquid refriger-
ant 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 65°F to 105°F. If outdoor ambi-
ent temperature is out of range, charge defined amount and don't
adjust subcooling. Set the room thermostat to CHARGE MODE.
After system has stabilized per startup instructions, check
subcooling as detailed in the following section.
In the event of system overcharge or undercharge, refrigerant
in the system must be adjusted to the appropriate subcooling
and superheat as specified in the following sections. Refrig-
erant amount should be adjusted /- 0.5 lb. if the out-
door ambient temperature is greater than 65°F and less than
105°F. Manufacturer recommends that the system should be
evacuated and should be charged the initial refrigerant for
given line length when the ambient temperature is less than
65°F and more than 105°F. Refer to the Installation Manual to
calculate refrigerant amount.
5. With the system still running, remove hose and reinstall both
valve caps.
6. Check system for leaks.
NOTE
: Subcooling information is valid only while the unit is operat-
ing at 100% capacity or 100% of compressor speed in CHARGE MODE.
Compressor speed is displayed under STATUS menu in the thermo-
stat.
S-104
CHECKING COMPRESSOR EFFICIENCY
The reason for compressor inefficiency is that the compressor is
broken or damaged, reducing the ability of the compressor to
pump refrigerant vapor.
The condition of the compressor is checked in the following man-
ner.
1. Attach gauges to the high and low side of the system.
2. Start the system and run CHARGE MODE.
If the test shows:
a. Below normal high side pressure.
b. Above normal low side pressure.
c. Low temperature difference across coil.
d. Low amp draw at compressor.
And the charge is correct. The compressor is faulty - replace the
compressor.
S-105B THERMOSTATIC EXPANSION VALVE
The expansion valve is designed to control the rate of liquid re-
frigerant flow into an evaporator coil in exact proportion to the
rate of evaporation of the refrigerant in the coil. The amount of
refrigerant entering the coil is regulated since the valve responds
to temperature of the refrigerant gas leaving the coil (feeler bulb
contact) and the pressure of the refrigerant in the coil. This regu-
lation of the flow prevents the return of liquid refrigerant to the
compressor.
Some TXV valves contain an internal check valve thus eliminating
the need for an external check valve and bypass loop. The three
forces which govern the operation of the valve are: (1) the pres-
sure created in the power assembly by the feeler bulb, (2) evapo-
rator pressure, and (3) the equivalent pressure of the superheat
spring in the valve.
