18
3. Refer to the superheat table provided for
proper system superheat. Add charge to lower
superheat or recover charge to raise superheat.
Superheat Formula = Suct. Line Temp. - Sat. Suct.
Temp.
Superheat Adjustment
NOTE:
The expansion valve will not need adjustment for
most applications. Ensure system superheat is set within
range listed on chart below.
To adjust superheat, unscrew the cover from the expansion
valve, locate the adjustment screw, and turn it clockwise (in)
to increase superheat or counterclockwise (out) to decrease
superheat. Replace adjustment cap. Wait a minimum of 10
minutes between adjustments to allow time for the TXV and
pressures to stabilize.
65
70
75
80
85
100
-
-
-
10
10
95
-
-
10
10
10
90
-
-
12
15
18
85
-
10
13
17
20
80
-
10
15
21
26
75
10
13
17
25
29
70
10
17
20
28
32
65
13
19
26
32
35
60
17
25
30
33
37
Ambient
Condenser Inlet
Temp (°F Drybulb)
Return Air Temp. (°F Drybulb)
Checking Subcooling
Refrigerant liquid is considered subcooled when its tempera-
ture is lower than the saturation temperature corresponding
to its pressure. The degree of subcooling equals the degrees
of temperature decrease below the saturation temperature
at the existing pressure.
1. Attach an accurate thermometer or preferably a
thermocouple type temperature tester to the liquid
line close to the pressure switch.
2. Install a high side pressure gauge on the liquid access
fitting.
3. Record the gauge pressure and the temperature of
the line.
4.
The difference between the thermometer reading and
pressure to temperature conversion is the amount of
subcooling.
Subcooling Formula = Sat. Liquid Temp. - Liquid
Line Temp.
EXAMPLE:
a. Liquid Line Pressure = 417
b. Corresponding Temp. °F. = 120°
c. Thermometer on Liquid line = 109°F.
To obtain the amount of subcooling, subtract 109°F from
120°F. The difference is 11° subcooling. See the specification
sheet or technical information manual for the design subcool-
ing range for your unit.
Cooling Operation
NOTE:
Mechanical cooling cannot be reliably provided at
ambient temperatures below 50° F.
1. Turn on the electrical power supply to the unit.
2. Place the room thermostat selector switch in the
COOL position (or AUTO if available, and if automatic
changeover from cooling to heating is desired).
3. Set the room thermostat to the desired temperature.
TROUBLESHOOTING
Ignition Control Error Codes
The following presents probable causes of questionable unit
operation. Refer to
Diagnostic Indicator Chart
for an inter-
pretation of the signal and to this section for an explanation.
Remove the control box access panel and note the num-
ber of diagnostic LED flashes. Refer to
Diagnostic Indicator
Chart
for an interpretation of the signal and to this section for
an explanation.
Fault Recall
The ignition control is equipped with a momentary push-but-
ton switch that can be used to display on the diagnostic LED
the last five faults detected by the control. The control must
be in Standby Mode (no thermostat inputs) to use the fea-
ture. Depress the push-button switch for approximately 2
seconds.
NOTE: Do not hold for longer than 4 seconds.
Holding the button for 4 seconds or higher will erase the
memory!
Release the switch when the LED is turned off.
The diagnostic LED will then display the flash codes associ
-
ated with the last five detected faults. The order of display is
the most recent fault to the least recent fault.
Abnormal Operation - Heating
Internal Control Failure
If the integrated ignition control in this unit encounters an
internal fault, it will go into a “hard” lockout and turn off the
diagnostic LED. If diagnostic LED indicates an internal fault,
check power supply to unit for proper voltage, check all fus-
es, circuit breakers and wiring. Disconnect electric power
for five seconds. If LED remains off after restoring power,
replace control.
External Lockout
An external lockout occurs if the integrated ignition control
determines that a measurable combustion cannot be estab-
lished within three (3) consecutive ignition attempts. If flame
is not established within the seven (7) second trial for igni-
tion, the gas valve is de-energized, 30 second inter-purge
cycle is completed, and ignition is re-attempted. The control
will repeat this routine three times if a measurable combus-
tion is not established. The control will then shut off the in
-
duced draft blower and go into a lockout state.
If flame is established but lost, the control will energize the
circulator blower at the heat speed and then begin a new
ignition sequence. If flame is established then lost on subse
-
quent attempts, the control will recycle the ignition sequence.
