Trane NO Series, Installation Instructions Manual

16

OPERATING SEQUENCE

The operating sequences for the heating, cooling, and fan 

modes are described below. Refer to the field and unit wiring 

diagram. See 

Figure 12 (page 24)

.

Heating Cycle

1. The thermostat calls for heat by energizing the 

W

 terminal 

with 24VAC.

2. The control verifies the safety circuit pressure switch is open 

and high temperature limit switch circuit is closed.

3. If the pressure switch is open, the control energizes the 

inducer and waits for the pressure switch to close. The 

pressure switch must close within 10 seconds.

4. The control runs the inducer for a 30 second pre-purge.

5. The control energizes the igniter output for a 30 second 

warm-up period.

6. The control energizes the main gas valve for 3 seconds.

7. If the flame is proved after igniting the gas, the control de-

energizes the igniter. The gas valve and inducer remain 

energized. The control goes to blower on delay.

8. If flame is present, the control energizes the blower on 

the selected HEAT speed 30 seconds after the gas valve 

opened. The gas valve remains energized while the inducer 

ramps to Max. RPM over a programmed time period.

9. When the thermostat demand for heat is satisfied, the control 

de-energizes the gas valve. The inducer output remains on 

for a 90 second post-purge period.

10. Blower off timing of 60, 90, 120, & 180 seconds (depending 

on the movable jumper setting) begins when the thermostat 

is satisfied. See Figure 14 (page 16). The control will 

operate at the selected HEAT speed of 60 seconds, then 

change to FAN speed for the remaining off delay time. If 

the blower off delay jumper is not present, the fan should 

still operate for 120 seconds at the selected HEAT speed. 

The indoor blower motor is de-energized after a blower off 

delay as selected by the movable jumper.

Cooling Cycle

1. The thermostat calls for cooling by energizing the 

Y

 & 

G

terminal with 24VAC.

2. The control energizes the blower in the cooling speed and 

sends 24VAC to the contactor in the condensing section.

3. When the thermostat removes the call for cooling, the 

contactor in the outdoor condensing section is de-energized 

and the control continues to run the fan for a period of 60 

seconds.

Fan Mode

•  When the thermostat energizes the 

G

 terminal for continuous 

fan (without calling for heat or cooling), the indoor fan is 

energized on the selected FAN speed. See Figure ## (Page 

##). The control defaults to MEDIUM HIGH if the movable 

jumper is not attached.

•  If a call for cooling occurs during continuous fan, the blower 

will switch over to the selected COOL speed.

•  If the 

W

 terminal receives a call for heat during continuous 

fan, the blower will de-energize and reset to delayed ON 

timing.

•  A call for fan is ignored while in lockout.

EQUIPMENT MAINTENANCE

 WARNING:

ELECTRICAL SHOCK, FIRE OR

EXPLOSION HAZARD

Failure to follow safety warnings exactly could 

result in serious injury, death, or property damage.
Improper servicing could result in dangerous 

operation, serious injury, death or property 

damage.
•  Before servicing, disconnect all electrical power 

to furnace.

•  When servicing controls, label all wires prior to 

disconnecting. Reconnect wires correctly.

•  Verify proper operation after servicing.

 AVERTISSEMENT:

RISQUE D’ÉLECTROCUTION, D’INCENDIE

OU D’EXPLOSION

Si les consignes de sécurité ne sont pas suivies 

à la lettre, cela peut entraîner la mort, de graves 

blessures, un fonctionnement dangereux ou des 

dommages matériels.
Un entretien inadéquat peut entraîner la mort, de 

graves blessures, un fonctionnement dangereux 

ou des dommages matériels.
• Avant de faire l’entretien de l’appareil de 

chauffage, le débrancher de l’alimentation 

électrique.

•  Avant l’entretien des commandes, étiqueter tous 

les fils avant de les déconnecter. Rebrancher 

correctement les fils.

•  Vérifier que l’appareil fonctionne correctement 

après l’entretien.

 CAUTION:

Use care when removing parts from this unit. 

Personal injury can result from sharp metal edges 

present in all equipment of sheet metal construction.

Proper maintenance is important to achieve optimum 

performance from the system. The ability to properly perform 

maintenance on this equipment requires certain mechanical 

skills and tools. If you do not possess these skills, contact your 

dealer for maintenance. Consult your local dealer about the 

availability of maintenance contracts. Routine maintenance 

should include the following: