York W)036 THRU 060 Specifications download pdf (Page 56)

542300-YIM-A-1009

56 Johnson Controls Unitary Products

short delay (the room thermostat fan switch is in “AUTO”

position).

1. Place the thermostat fan switch in the “ON” position. If the

supply air blower motor energizes, go to Step 10.

2. If the supply air blower motor does not energize when the

fan switch is set to “ON,” check that line voltage is being

supplied to the contacts of the M2 contactor, and that the

contactor is pulled in. Check for loose wiring between the

contactor and the supply air blower motor.

3. If M2 is pulled in and voltage is supplied at M2, lightly touch

the supply air blower motor housing. If it is hot, the motor

may be off on inherent protection. Cancel any thermostat

calls and set the fan switch to “AUTO”, wait for the internal

overload to reset. Test again when cool.

4. If M2 is not pulled in, check for 24 volts at the M2 coil. If 24

volts is present at M2 but M2 is not pulled in, replace the

contactor.

5. Failing the above, if there is line voltage supplied at M2, M2

is pulled in, and the supply air blower motor still does not

operate, replace the motor.

6. If 24 volts is not present at M2, check that 24 volts is

present at the supply air blower motor terminal on the UCB.

If 24 volts is present at the UCB terminal, check for loose

wiring between the UCB and M2.

7. If 24 volts is not present at the UCB supply air blower motor

terminal, check for 24 volts from the room thermostat. If 24

volts is not present from the room thermostat, check for the

following:

a. Proper operation of the room thermostat (contact

between R and G with the fan switch in the “ON”

position and in the “AUTO” position during operation

calls).

b. Proper wiring between the room thermostat and the

UCB.

c. Loose wiring from the room thermostat to the UCB.

8. If 24 volts is present at the room thermostat but not at the

UCB, check for proper wiring between the thermostat and

the UCB, i.e. that the thermostat G terminal is connected to

the G terminal of the UCB, and for loose wiring.

9. If the thermostat and UCB are properly wired, replace the

UCB.

10. If the blower motor runs with the fan switch in the “ON”

position but does not run shortly after the furnace has

ignited when the fan switch is in the “AUTO” position,

check the room thermostat for contact between R and G

during “W1” calls.

On calls for heating, the supply air blower operates but the draft

motor does not (the room thermostat fan switch is in the

“AUTO” position).

1. The draft motor has inherent protection. If the motor shell is

hot to the touch, wait for the internal overload to reset.

2. If the motor shell is cold with the room thermostat calling

for heat, check if 24 volts is present at the room thermostat

but not at the UCB, check for proper wiring between the

thermostat and the UCB, i.e. that the thermostat “W1”

terminal is connected to the “W1” terminal of the UCB, and

for loose wiring.

3. The draft motor is a 230 volt draft motor on all models

regardless of unit supply voltage. If the ICB is flashing a

code other than the heartbeat, then troubleshoot the device

indicated by the fault code. If not, then remove power to the

unit for more than 20 seconds. If upon restoring the power

to the unit the draft motor does not start with a call for heat,

then verify that terminal “L1” of the ICB has a minimum of

120 volts to ground on 230 and 460 volt models or a

minimum of 18 volts to ground on 575 volt models. If

terminal “L1” does not have the minimum voltage, then

check the wiring between the unit control box and the ICB

on all models and on 460 volt models, the transformer in

the gas heat compartment and its wiring. If terminal “L1”

does have the minimum voltage, then check for the

minimum voltage on terminal “IND” of the ICB on single

stage models and terminal “IND HIGH” of the ICB on two

stage models. If voltage is not present at the terminal, then

verify wiring between the control box and the ICB. If all

wiring is intact, then ICB is at fault. If voltage is present at

the terminal on 230 and 460 volt models, then the draft

motor is at fault. On 575 volt models, if voltage is present at

the terminal, then check the draft motor relay (DMR on

single stage gas heat and DMR-2 on two stage gas heat)

mounted above the ICB. First verify that the relay is pulled

in by visual inspection. If not, then verify the minimum

voltage is present between terminals “A” and “B” of the

relay. If the minimum voltage is not present, then check the

wiring. If it is present, then verify that a minimum of 150

volts is present at terminals “5” and “7” of the draft motor

relay. If not present at terminal “7” of the draft motor relay,

then troubleshoot the transformer in blower section and its

wiring. If present at terminal “7” and not at terminal “5” of

the draft motor relay, then the relay is at fault. If the

minimum voltage is present at terminal 5 of the draft motor

relay, then the draft motor is at fault.

The ignitor sparks at the pilot burner but the pilot does not ignite

and a gas odor is detected at the draft motor outlet.

1. Adjust the pilot adjust screw on the gas valve as described

in “PILOT CHECKOUT” on page 48.

2. Check the supply pressure as described in “POST START

CHECK LIST” on page 47. Make adjustments as

necessary.

3. Check the pilot orifice and pilot burner for obstruction as

described in paragraph above. Clean as needed but the

problem should not be the gas valve.

The pilot burner ignites but the ignitor continues to spark and

the main burners do not ignite.

1. Make the same checks and adjustment as described in

“PILOT CHECKOUT” on page 48.

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York W)036 THRU 060 Specifications Page 56

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