Carrier 48TCA04---A12 Service And Maintenance Instructions

63Single EnthalpyTo check single enthalpy:1. Make sure EconoMi$er IV preparation procedure hasbeen performed.2. Set the enthalpy potentiometer to A (fully CCW). TheFree Cool LED should be lit.3. Set the enthalpy potentiometer to D (fully CW). TheFree Cool LED should turn off.4. Return EconoMi$er IV settings and wiring to normalafter completing troubleshooting.DCV (Demand Controlled Ventilation) and PowerExhaustTo check DCV and Power Exhaust:1. Make sure EconoMi$er IV preparation procedure hasbeen performed.2. Ensure terminals AQ and AQ1 are open. The LED forboth DCV and Exhaust should be off. The actuatorshould be fully closed.3. Connect a 9--v battery to AQ (positive node) and AQ1(negative node). The LED for both DCV and Exhaustshould turn on. The actuator should drive to between90 and 95% open.4. Turn the Exhaust potentiometer CW until the ExhaustLED turns off. The LED should turn off when the po-tentiometer is approximately 90%. The actuatorshould remain in position.5. Turn the DCV setpoint potentiometer CW until theDCV LED turns off. The DCV LED should turn offwhen the potentiometer is approximately 9--v. The ac-tuator should drive fully closed.6. Turn the DCV and Exhaust potentiometers CCW untilthe Exhaust LED turns on. The exhaust contacts willclose 30 to 120 seconds after the Exhaust LED turnson.7. Return EconoMi$er IV settings and wiring to normalafter completing troubleshooting.DCV Minimum and Maximum PositionTo check the DCV minimum and maximum position:1. Make sure EconoMi$er IV preparation procedure hasbeen performed.2. Connect a 9--v battery to AQ (positive node) and AQ1(negative node). The DCV LED should turn on. Theactuator should drive to between 90 and 95% open.3. Turn the DCV Maximum Position potentiometer tomidpoint. The actuator should drive to between 20and 80% open.4. Turn the DCV Maximum Position potentiometer tofully CCW. The actuator should drive fully closed.5. Turn the Minimum Position potentiometer to mid-point. The actuator should drive to between 20 and80% open.6. Turn the Minimum Position Potentiometer fully CW.The actuator should drive fully open.7. Remove the jumper from TR and N. The actuatorshould drive fully closed.8. Return EconoMi$er IV settings and wiring to normalafter completing troubleshooting.Supply--Air Sensor InputTo check supply--air sensor input:1. Make sure EconoMi$er IV preparation procedure hasbeen performed.2. Set the Enthalpy potentiometer to A. The Free CoolLED turns on. The actuator should drive to between20 and 80% open.3. Remove the 5.6 kilo--ohm resistor and jumper T toT1. The actuator should drive fully open.4. Remove the jumper across T and T1. The actuatorshould drive fully closed.5. Return EconoMi$er IV settings and wiring to normalafter completing troubleshooting.EconoMi$er IV Troubleshooting CompletionThis procedure is used to return the EconoMi$er IV tooperation. No troubleshooting or testing is done byperforming the following procedure.1. Disconnect power at TR and TR1.2. Set enthalpy potentiometer to previous setting.3. Set DCV maximum position potentiometer to previ-ous setting.4. Set minimum position, DCV setpoint, and exhaust po-tentiometers to previous settings.5. Remove 620--ohm resistor from terminals SR and +.6. Remove 1.2 kilo--ohm checkout resistor from termin-als SO and +. If used, reconnect sensor from termin-als 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. Recon-nect wires at T and T1.10. Remove jumper from P to P1. Reconnect device at Pand P1.11. Apply power (24 vac) to terminals TR and TR1.WIRING DIAGRAMSSee Fig. 83 and Fig. 84 for typical wiring diagrams.48TC