Charging The Unit; Ignition Control Flash Codes; Unit Control Board - York ZF Series Installation Manual

5326602-XIM-B-1019

Charging The Unit

All ZF units use Thermal Expansion Devices. Charge the unit to
nameplate charge or 10° subcooling.
W1
W2
Y1
G
Y2
THERMOSTAT
WIRED HERE
OCC
X
R
SD-24
C
Figure 32: Unit Control Board
54
Table 35: Ignition Control Flash Codes
Flashes Fault Conditions
STEADY ON Control Failure
HEARTBEAT Normal Operation
1 Not Applicable
Pressure Switch
2
Stuck Closed
Pressure Switch Failed
3
To Close
4 Limit Switch Open
Flame Present With Gas
Off First Stage Gas Valve
Energized With W1 Off
5 Second Stage Gas Valve
Energized With First
Stage
Gas Valve Off
6 Ignition Lockout
No Power Or Control
STEADY OFF
Failure
Check
Control
Pressure Switch
Venter Pressure Switch
Vent Blocked
Main Limit
AUX Limit
Gas Valve
Gas Flow
Gas Pressure
Gas Valve
Flame Sensor
24VAC or Control
Johnson Controls Ducted Systems