515.28-N3Y
10
Unitary Products Group
door coil which is the condenser. The indoor coil is the
evaporator.
2.
If fan switch is in "ON" position, a circuit is made through
blower relay to provide continuous blower operation.
3.
Solid state YORKGUARD V starts time delay period.
After 5 minutes, the system is ready for operation.
4.
When thermostat cooling contact closes, a circuit is
made though the YORKGUARD V to energize contactor
and start the system. With fan switch in "AUTO" position,
a circuit is made from thermostat cooling contact through
blower relay to provide blower operation.
5.
System will cycle with thermostat demand to provide
cooling as needed.
6.
After the system has stopped from a cooling cycle or
power interruption, the YORKGUARD V will not permit
the system to re-start for 5 minutes. (This protects com-
pressor by allowing system pressures to equalize.)
7.
YORKGUARD V monitors system operation and will
lockout the outdoor unit if it detects a malfunction. When
a lockout occurs, the emergency heat light will flash at
the thermostat. In addition, the fault indicator light on
YORKGUARD V will flash and will continue flashing until
reset even if the lockout was cleared at the thermostat. It
can only be reset by shorting the "test" terminals on
Yorkguard V terminal block for 3 seconds and releasing.
The lights will flash the code, separated by a pause, indi-
cating the failure mode shown in Table 3.
8.
To restore operation after a lockout (if control causing
lockout has automatically reset);
a.
Turn the system switch on the thermostat to the
"OFF" position and return it to the cooling position,
within 5 seconds with a demand for cooling. (OR)
b.
Interrupt the line power or the 24 volt control circuit
power to the indoor unit for 4 seconds..
NOTE:
Either of the above methods will start the 5-minute
time delay which may be bypassed by temporarily shorting
the test terminals for 3 seconds.
FIGURE 8 : HEAT PUMP FLOW DIAGRAM
Table 3: Legend of Flashing Light Codes
FAULT
CODE
FAILURE MODE
2
Discharge pressure reaches approx. 400 PSIG
3
Discharge temperature reaches approx. 275
°
F
4
Discharge temperature did not reach approx. 90
°
F
within 1 hour of compressor operation.
5
Two default defrosts within one hour caused by
outdoor fan motor failure, low refrigerant charge or
restricted capillary tube or drier.
6
Discharge Sensor failure
7
*
*.
NOTE: In Cooling mode, failures 7, 8 and 9 will not
cause the outdoor unit to lockout, but will only flash the
light. In Heating mode, failures 7 and 8 will not cause
the outdoor unit to lockout, but will flash the light and
continue.
Outdoor temperature sensor failure
8*
Liquid line temperature sensor failure
9*
Bonnet sensor shorted
