Carrier 48TC 04 Series Service And Maintenance Instructions page 85

4. Use the Up/Down button to toggle through each of
the nine variables, starting with Altitude, until the
desired setting is reached.
5. Press Mode to move through the variables.
6. Press Enter to lock in the selection, then press Mode
to continue to the next variable.
Dehumidification of Fresh Air with DCV (Demand
Controlled Ventilation) Control
If normal rooftop heating and cooling operation is not
adequate for the outdoor humidity level, an energy
recovery unit and/or a dehumidification option should be
considered.
EconoMi$er IV Preparation
This procedure is used to prepare the EconoMi$er IV for
troubleshooting. No troubleshooting or testing is done by
performing the following procedure.
NOTE: This procedure requires a 9- - v battery, 1.2
kilo- - ohm resistor, and a 5.6 kilo- - ohm resistor which are
not supplied with the EconoMi$er IV.
IMPORTANT: Be sure to record the positions of all
potentiometers before starting troubleshooting.
1. Disconnect power at TR and TR1. All LEDs should
be off. Exhaust fan contacts should be open.
2. Disconnect device at P and P1.
3. Jumper P to P1.
4. Disconnect wires at T and T1. Place 5.6 kilo- - ohm
resistor across T and T1.
5. Jumper TR to 1.
6. Jumper TR to N.
7. If connected, remove sensor from terminals SO and
+. Connect 1.2 kilo- - ohm 4074EJM checkout resistor
across terminals SO and +.
8. Put 620- - ohm resistor across terminals SR and +.
9. Set minimum position, DCV setpoint, and exhaust
potentiometers fully counterclockwise (CCW).
10. Set DCV maximum position potentiometer fully
clockwise (CW).
11. Set enthalpy potentiometer to D.
12. Apply 24 VAC power to terminals TR and TR1.
Differential Enthalpy
To check differential enthalpy:
1. Make sure EconoMi$er IV preparation procedure
has been performed.
2. Place 620- - ohm resistor across SO and +.
3. Place 1.2 kilo- - ohm resistor across SR and +. The
Free Cool LED should be lit.
4. Remove 620- - ohm resistor across SO and +. The
Free Cool LED should turn off.
5. Return EconoMi$er IV settings and wiring to normal
after completing troubleshooting.
Single Enthalpy
To check single enthalpy:
1. Make sure EconoMi$er IV preparation procedure
has been performed.
2. Set the enthalpy potentiometer to A (fully CCW).
The Free Cool LED should be lit.
3. Set the enthalpy potentiometer to D (fully CW). The
Free Cool LED should turn off.
4. Return EconoMi$er IV settings and wiring to normal
after completing troubleshooting.
DCV (Demand Controlled Ventilation) and Power
Exhaust
To check DCV and Power Exhaust:
1. Make sure EconoMi$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 actuat-
or 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 Ex-
haust LED turns off. The LED should turn off when
the potentiometer is approximately 90%. The actuat-
or should remain in position.
5. Turn the DCV setpoint 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 un-
til 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
midpoint. 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 mid-
point. The actuator should drive to between 20 and
80% open.
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