4.Tighten setscrews and replace rubber hubcap to pre- vent hub from rusting to motor shaft.
5.Fill hub recess with permagum if rubber hubcap is missing.
VII. ECONOMIZER ADJUSTMENT
See Tables 16 and 17 for checkout and outdoor air tempera- ture simulation. Make certain the
1.Turn on power to the unit.
2.Turn the thermostat fan switch to the ON position. The damper will go to the vent position.
3.Adjust the vent position with the minimum damper- position adjustment on the economizer motor control module. See Fig. 18.
4.Set the system selector switch to COOL position and set the cooling temperature selector to its lowest setting.
NOTE: The Cooling mode may also be simulated by removing the thermostat wires from terminals Y1 and Y2 and installing a jumper between terminals R and Y1. Refer to unit label diagram for terminal locations.
Table 16 — Economizer Checkout Procedures
TEST PROCEDURE | RESULTS |
A. Disconnect power at |
|
TR and TR1. |
|
Disconnect jumper |
|
between P and |
|
P1. See Fig. 18. |
|
B. Jumper TR to 1. |
|
C. Jumper T1 to T. |
|
D. Disconnect |
|
thermostat connections |
|
from SO and +. |
|
| |
800 ohm resistor |
|
should remain connected |
|
to SR and +. |
|
E. Reconnect power to |
|
terminals TR and TR1. |
|
| 1. LED |
| should be off. |
| 2. Motor is in closed position. |
|
|
TEST PROCEDURE |
| RESULTS |
Disconnect |
|
|
resistor from terminals |
|
|
SR and +. | 1. | LED should be on. |
| ||
| 2. | Motor drives toward open. |
Table 17 — High and Low Outdoor-Air Simulation
TEST PROCEDURE | RESULTS |
A. Reconnect |
|
800 ohm resistor |
|
between terminals |
|
SR and +. |
|
B. Connect 1200 ohm |
|
checkout resistor between |
|
terminals SO and +. |
|
C. Turn set point potentiometer |
|
to position A. |
|
| Low |
| 1. LED |
| diode)should be on. |
| 2. Motor drives toward open. |
D. Turn set point potentiometer |
|
to position D. |
|
E. Disconnect 1200 ohm |
|
checkout resistor. |
|
| High |
| 1. LED should be off. |
| 2. Motor drives toward closed. |
5.Set the
6.If the outdoor temperature is below 75 F, the econo- mizer will control the mixed air with the
7.Jumper terminal T to terminal T1 on the module (see Fig. 18). The economizer will go to the full open posi- tion. The
8.Adjust mechanical linkage, if necessary, for correct positioning. If may be necessary to remove the filters to adjust the linkage.
9.Remove the jumper from around the contacts of the OAT if installed in Step 6. Remove the jumper from terminals T and T1 installed in Step 7.
10.If the Cooling mode was simulated to operate the unit in Step 4, remove the jumper and reconnect the ther- mostat wires to terminals Y1 and Y2.
VIII. POWER FAILURE
Dampers have a spring return. In event of power failure, dampers will return to fully closed position until power is restored. Do not manually operate damper motor.
IX. REFRIGERANT CHARGE
Amount of refrigerant charge is listed on unit nameplate and in Table 1. Refer to Carrier GTAC II; Module 5; Charging, Recovery, Recycling, and Reclamation section for charging methods and procedures. Unit panels must be in place when unit is operating during charging procedure.
NOTE: Do not use recycled refrigerant as it may contain contaminants.
A. No Charge
Use standard evacuating techniques. After evacuating sys- tem, weigh in the specified amount of refrigerant (refer to Table 1).
B. Low Charge Cooling
Using appropriate cooling charging chart (see Fig. 35), add or remove refrigerant until conditions of the chart are met. Note that charging chart is different from those normally used. An accurate pressure gage and
C. To Use the Cooling Charging Chart
Use the above temperature and pressure readings, and find the intersection point on the cooling charging chart. If inter- section point on chart is above line, add refrigerant. If inter- section point on chart is below line, carefully recover some of the charge. Recheck suction pressure as charge is adjusted.
NOTE:
The TXV (thermostatic expansion valve) is set to maintain between 15 and 20 degrees of superheat at the compressors. The valves are factory set and should not require