Carrier Furnace Troubleshooting and Blower Speed Chart for Efficient Operation

		HUM
		G
		R
		Y/Y2
		W/W1
		Com	24V
		W2
SEC-2	SEC-1	DEHUM

		HUM
		G
		R
		Y/Y2
		W/W1
		Com	24V
		W2
		DE
SEC-2	SEC-1	DEHUM

DE CONNECTION

WITHOUT DE	WITH DE
CONNECTION	CONNECTION

Fig. 1ÐVariable Speed Furnace Control

A98293

b.R-W/W1 with R-Y/Y2 and R-G signals terminatedÐ The blower continues to operate completing a normal blower off delay.

11.Post purgeÐThe inducer continues operating for 15 sec after gas valve is de-energized.

Step 7ÐContinuous Fan Mode

1.Operating with continuous fan only.

a.Call for continuous fanÐThe thermostat closes R-G circuit.

b.Blower onÐThe blower starts immediately.

NOTE: The blower starts at approximately 400-500 RPM. After 20 sec, the motor is turned off for 1/10 of a sec where a coast down calibration is done to evaluate resistance of the conditioned air duct system. The microprocessor then determines blower RPM required to provide proper airflow for heating mode.

NOTE: The continuous fan speed is the same as low-heat speed unless it is field adjusted to another desired airflow. See Continu- ous Fan Setup Switches section in Installation, Start-Up, and Operating Instructions for details. There is also a chart on schematic diagram shown in Appendix A.

c. Electronic Air CleanerÐThe EAC-1 terminal is ener- gized whenever blower operates, regardless of operating mode.

for cooling (R-Y/Y2) is terminated, the blower remains operating at cooling speed for 90 sec before resuming con- tinuous fan speed.

Step 8ÐComponent Test

All components are functionally operated except gas valve with component test feature.

This feature helps diagnose a system problem in case of a component failure.

NOTE: Setup switch SW-1 MUST be in OFF position or Fault Code 22 (setup error) will occur.

NOTE: NO thermostat signal may be present at control center, and all blower time delay off periods must be completed.

To initiate component test feature, proceed with the following:

1.Leave 115-v power to furnace turned on.

2.Remove main furnace door.

3.Remove blower access panel.

4.Turn setup switch SW-6 to ON position.

5.Manually close blower access panel door switch.

2.Operating with continuous fan (R-G) and call for heat (R-W/W1) is receivedÐSame as heat pump mode except blower on delay is 10 sec less than the heat mode. After call for heat (R-W/W1) is terminated, the blower remains operat- ing at low-heat speed for selected blower off delay before resuming continuous fan speed.

3.Operating with continuous fan (R-G) and call for cooling (R-Y/Y2) is receivedÐSee Cooling Mode section. After call

On some models, blower access panel door switch opens only 24-v power to control center. No component operation can occur. The 115-v power is still present at control center, transformer, inducer motor, and main blower motor. Caution must be taken when manually closing this switch for service purposes. Failure to follow this warning could result in personal injury or death.

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