Carrier 48PG20-28 specifications MIXED-AIRINPUT - To check mixed-airinput

DCV (Demand Controlled Ventilation) AND POWER EXHAUST — To check DCV and Power Exhaust:

1.Make sure EconoMi$er IV preparation procedure has been performed.

2.Ensure terminals AQ and AQ1 are open. The LED for both DCV and Exhaust should be off. The actuator should be fully closed.

3.Connect a 9-v battery to AQ (positive node) and AQ1 (negative node). The LED for both DCV and Exhaust should turn on. The actuator should drive to between 90 and 95% open.

4.Turn the Exhaust potentiometer CW until the Exhaust LED turns off. The LED should turn off when the potentiometer is approximately 90%. The actuator should remain in position.

5.Turn the DCV set point potentiometer CW until the DCV LED turns off. The DCV LED should turn off when the potentiometer is approximately 9 v. The actuator should drive fully closed.

6.Turn the DCV and Exhaust potentiometers CCW until the Exhaust LED turns on. The exhaust contacts will close 30 to 120 seconds after the Exhaust LED turns on.

7.Return EconoMi$er IV settings and wiring to normal after completing troubleshooting.

DCV MINIMUM AND MAXIMUM POSITION — To check the DCV minimum and maximum position:

1.Make sure EconoMi$er IV preparation procedure has been performed.

2.Connect a 9-v battery to AQ (positive node) and AQ1 (negative node). The DCV LED should turn on. The actuator should drive to between 90 and 95% open.

3.Turn the DCV Maximum Position potentiometer to mid- point. The actuator should drive to between 20 and 80% open.

4.Turn the DCV Maximum Position potentiometer to fully CCW. The actuator should drive fully closed.

5.Turn the Minimum Position potentiometer to midpoint. The actuator should drive to between 20 and 80% open.

6.Turn the Minimum Position Potentiometer fully CW. The actuator should drive fully open.

7.Remove the jumper from TR and N. The actuator should drive fully closed.

8.Return EconoMi$er IV settings and wiring to normal after completing troubleshooting.

MIXED-AIR INPUT — To check mixed-air input:

1.Make sure EconoMi$er IV preparation procedure has been performed.

2.Set the Enthalpy potentiometer to A. The Free Cool LED turns on. The actuator should drive to between 20 and 80% open.

3.Remove the 5.6 kilo-ohm resistor and jumper T to T1. The actuator should drive fully open.

4.Remove the jumper across T and T1. The actuator should drive fully closed.

5.Return EconoMi$er IV settings and wiring to normal after completing troubleshooting.

ECONOMI$ER IV TROUBLESHOOTING COMPLE- TION — This procedure is used to return the EconoMi$er IV to operation. No troubleshooting or testing is done by perform- ing the following procedure.

1.Disconnect power at TR and TR1.

2.Set enthalpy potentiometer to previous setting.

3.Set DCV maximum position potentiometer to previous setting.

4.Set minimum position, DCV set point, and exhaust potentiometers to previous settings.

5.Remove 620-ohm resistor from terminals SR and +.

6.Remove 1.2 kilo-ohm checkout resistor from terminals SO and +. If used, reconnect sensor from terminals SO and +.

7.Remove jumper from TR to N.

8.Remove jumper from TR to 1.

9.Remove 5.6 kilo-ohm resistor from T and T1. Reconnect wires at T and T1.

10.Remove jumper from P to P1. Reconnect device at P and P1.

11.Apply power (24 vac) to terminals TR and TR1.

Phase Loss Protection — The phase loss protection option will monitor the three-phase electrical system to provide phase reversal and phase loss protection.

PHASE REVERSAL PROTECTION — If the control sens- es an incorrect phase relationship, the relay (K1) will be de- energized (opening its contact). If the phase relationship is correct, the relay will be energized. The control has a self- bypass function after a pre-set time. If the control determines that the three phases stay in a correct relationship for 10 con- secutive minutes, the relay will stay energized regardless of the phase sequence of three inputs as long as 24-vac control voltage is applied. This self-bypass function will be reset if all three phases are restored in a phase loss event.

PHASE LOSS PROTECTION — If the reverse rotation board senses any one of the three phase inputs has no AC voltage, the relay will be deenergized (opening its contact). This protection is always active as long as 24-vac control volt- age is applied, and is not affected by the self bypass function of the phase sequence monitoring function. However, in the event of phase loss, the relay will be re-energized only if all three phases are restored and the three phases are in the correct sequence.

A red LED is provided to indicate the function of the board. See the table below.

LED STATUS	FUNCTION
On Continuously	Relay contact closed (normal operation).
Blinking	Relay contact open (phase loss or phase
	reversal has occurred) — No power will be
	supplied to the control system.
Off	24 vac control power not present (off).

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