Carrier SINGLE PACKAGE ROOFTOP UNITS 48PG20-28 Installation And Service Instructions Manual

Also see for 48PG20---28: User's information manual User's information manual Controls, start-up, operation, service and troubleshooting instructions

Carrier SINGLE PACKAGE ROOFTOP UNITS 48PG20-28 Installation And Service Instructions Manual Manual pdf 61 page image

61DCV (Demand Controlled Ventilation) AND POWEREXHAUST — To check DCV and Power Exhaust:1. Make sure EconoMi$er IV preparation procedure hasbeen performed.2. Ensure terminals AQ and AQ1 are open. The LED forboth DCV and Exhaust should be off. The actuatorshould be fully closed.3. Connect a 9-v battery to AQ (positive node) and AQ1(negative node). The LED for both DCV and Exhaustshould turn on. The actuator should drive to between 90and 95% open.4. Turn the Exhaust potentiometer CW until the ExhaustLED turns off. The LED should turn off when thepotentiometer is approximately 90%. The actuator shouldremain in position.5. Turn the DCV set point potentiometer CW until the DCVLED turns off. The DCV LED should turn off when thepotentiometer is approximately 9 v. The actuator shoulddrive fully closed.6. Turn the DCV and Exhaust potentiometers CCW untilthe Exhaust LED turns on. The exhaust contacts willclose 30 to 120 seconds after the Exhaust LED turns on.7. Return EconoMi$er IV settings and wiring to normalafter completing troubleshooting.DCV MINIMUM AND MAXIMUM POSITION — To checkthe DCV minimum and maximum position:1. Make sure EconoMi$er IV preparation procedure hasbeen performed.2. Connect a 9-v battery to AQ (positive node) and AQ1(negative node). The DCV LED should turn on. Theactuator should drive to between 90 and 95% open.3. Turn the DCV Maximum Position potentiometer to mid-point. The actuator should drive to between 20 and 80%open.4. Turn the DCV Maximum Position potentiometer to fullyCCW. The actuator should drive fully closed.5. Turn the Minimum Position potentiometer to midpoint.The actuator should drive to between 20 and 80% open.6. Turn the Minimum Position Potentiometer fully CW. Theactuator should drive fully open.7. Remove the jumper from TR and N. The actuator shoulddrive fully closed.8. Return EconoMi$er IV settings and wiring to normalafter completing troubleshooting.MIXED-AIR INPUT — To check mixed-air input:1. Make sure EconoMi$er IV preparation procedure hasbeen performed.2. Set the Enthalpy potentiometer to A. The Free Cool LEDturns on. The actuator should drive to between 20 and80% open.3. Remove the 5.6 kilo-ohm resistor and jumper T to T1.The actuator should drive fully open.4. Remove the jumper across T and T1. The actuator shoulddrive fully closed.5. Return EconoMi$er IV settings and wiring to normalafter completing troubleshooting.ECONOMI$ER IV TROUBLESHOOTING COMPLE-TION — This procedure is used to return the EconoMi$er IVto 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 previoussetting.4. Set minimum position, DCV set point, and exhaustpotentiometers to previous settings.5. Remove 620-ohm resistor from terminals SR and +.6. Remove 1.2 kilo-ohm checkout resistor from terminalsSO 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. Reconnectwires at T and T1.10. Remove jumper from P to P1. Reconnect device at P andP1.11. Apply power (24 vac) to terminals TR and TR1.Phase Loss Protection — The phase loss protectionoption will monitor the three-phase electrical system to providephase 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 iscorrect, the relay will be energized. The control has a self-bypass function after a pre-set time. If the control determinesthat the three phases stay in a correct relationship for 10 con-secutive minutes, the relay will stay energized regardless of thephase sequence of three inputs as long as 24-vac controlvoltage is applied. This self-bypass function will be reset if allthree phases are restored in a phase loss event.PHASE LOSS PROTECTION — If the reverse rotationboard senses any one of the three phase inputs has no ACvoltage, 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 ofthe phase sequence monitoring function. However, in the eventof phase loss, the relay will be re-energized only if all threephases are restored and the three phases are in the correctsequence.A red LED is provided to indicate the function of the board.See the table below.LED STATUS FUNCTIONOn Continuously Relay contact closed (normal operation).BlinkingRelay contact open (phase loss or phasereversal has occurred) — No power will besupplied to the control system.Off 24 vac control power not present (off).

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