York ZF036 Installation Manual

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826081-XIM-C-021442 Johnson Controls Unitary ProductsUnexpected Flame PresenceIf a flame is present without a call for heat (flash code 8), thenthe ICB will continue operation of the draft motor and the UCBwill call for indoor operation when either of the temperature limitopens. If the unit is correctly wired and there is not a call forheat, then check for control voltage to the gas valve. If controlvoltage exists at the gas valve, then replace the ICB. If voltageis not present at the gas valve, then replace the gas valve.Gas Valve Stuck Off Or OnIf the pilot and/or the main valves are sensed to be off morethan 1 second when commanded to be on, the control will shutoff all outputs and enter a hard lockout (flash code 9). Likewise,if the pilot and/or the main valves are sensed to be on morethan 1 second when commanded to be off, the control will shutoff all outputs and enter a hard lockout (flash code 9). Thecontrol will not respond to thermostat demands during a hardlockout. The only way to recover from a hard lockout is toremove and reapply 24VAC power to the control.Flame Sense Circuit FailureIf the control detects an internal hardware failure in the flamesense circuit, it shuts off all outputs and enters a hard lockout(flash code 10). The control will not respond to thermostatdemands during a hard lockout. The only way to recover from ahard lockout is to remove and reapply 24VAC power to thecontrol. If problem persist after removal and reapplication of24VAC power, the board may need to be replaced.Symptomatic TroubleShootingOn calls for heating, the draft motor operates and the furnacelights but the supply air blower motor does not energize after ashort delay (the room thermostat fan switch is in “AUTO”position).1. Place the thermostat fan switch in the “ON” position. If thesupply air blower motor energizes, go to Step 10.2. If the supply air blower motor does not energize when thefan switch is set to “ON,” check that line voltage is beingsupplied to the contacts of the M2 contactor, and that thecontactor is pulled in. Check for loose wiring between thecontactor and the supply air blower motor.3. If M2 is pulled in and voltage is supplied at M2, lightly touchthe supply air blower motor housing. If it is hot, the motormay be off on inherent protection. Cancel any thermostatcalls and set the fan switch to “AUTO”, wait for the internaloverload to reset. Test again when cool.4. If M2 is not pulled in, check for 24 volts at the M2 coil. If 24volts is present at M2 but M2 is not pulled in, replace thecontactor.5. Failing the above, if there is line voltage supplied at M2, M2is pulled in, and the supply air blower motor still does notoperate, replace the motor.6. If 24 volts is not present at M2, check that 24 volts ispresent at the supply air blower motor terminal on the UCB.If 24 volts is present at the UCB terminal, check for loosewiring between the UCB and M2.7. If 24 volts is not present at the UCB supply air blower motorterminal, check for 24 volts from the room thermostat. If 24volts is not present from the room thermostat, check for thefollowing:• Proper operation of the room thermostat (contactbetween R and G with the fan switch in the “ON”position and in the “AUTO” position during operationcalls).• Proper wiring between the room thermostat and theUCB.• Loose wiring from the room thermostat to the UCB.8. If 24 volts is present at the room thermostat but not at theUCB, check for proper wiring between the thermostat andthe UCB, i.e. that the thermostat G terminal is connected tothe G terminal of the UCB, and for loose wiring.9. If the thermostat and UCB are properly wired, replace theUCB.10. If the blower motor runs with the fan switch in the “ON”position but does not run shortly after the furnace hasignited when the fan switch is in the “AUTO” position,check the room thermostat for contact between R and Gduring “W1” calls.On calls for heating, the supply air blower operates but the draftmotor does not (the room thermostat fan switch is in the“AUTO” position).1. The draft motor has inherent protection. If the motor shell ishot to the touch, wait for the internal overload to reset.2. If the motor shell is cold with the room thermostat callingfor heat, check if 24 volts is present at the room thermostatbut not at the UCB, check for proper wiring between thethermostat and the UCB, i.e. that the thermostat “W1”terminal is connected to the “W1” terminal of the UCB, andfor loose wiring.3. The draft motor is a 230 volt draft motor on all modelsregardless of unit supply voltage. If the ICB is flashing acode other than the heartbeat, then troubleshoot the deviceindicated by the fault code. If not, then remove power to theunit for more than 20 seconds. If upon restoring the powerto the unit the draft motor does not start with a call for heat,then verify that terminal “L1” of the ICB has a minimum of120 volts to ground on 230 and 460 volt models or aminimum of 18 volts to ground on 575 volt models. Ifterminal “L1” does not have the minimum voltage, thencheck the wiring between the unit control box and the ICBon all models and on 460 volt models, the transformer inthe gas heat compartment and its wiring. If terminal “L1”does have the minimum voltage, then check for theminimum voltage on terminal “IND” of the ICB on singlestage models and terminal “IND HIGH” of the ICB on twostage models. If voltage is not present at the terminal, thenverify wiring between the control box and the ICB. If allwiring is intact, then ICB is at fault. If voltage is present atthe terminal on 230 and 460 volt models, then the draft