Table 11 Ð Economizer Checkout Procedures
TEST PROCEDURE | RESULTS |
A. Disconnect power at TR |
|
and TR1. |
|
Disconnect jumper |
|
between P and |
|
P1. See Fig. 15. |
|
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 |
A. Disconnect |
|
|
|
| |
resistor from |
|
|
terminals SR and +. | 1. | LED |
| ||
|
| should be on. |
| 2. | Motor drives toward open. |
|
|
|
Table 12 Ð High and Low Outdoor-Air
Temperature Simulation
TEST PROCEDURE | RESULTS |
A. Reconnect factory- |
|
installed 800 ohm resis- |
|
tor between terminals |
|
SR and +. |
|
B. Connect 1200 ohm |
|
checkout resistor |
|
between terminals |
|
SO and +. |
|
C. Turn set point poten- |
|
tiometer to position A. | Low |
| |
| test results: |
| 1. LED |
| should be on. |
| 2. Motor drives toward open. |
D. Turn set point poten- |
|
tiometer to position D. |
|
E. Disconnect 1200 ohm |
|
checkout resistor. | High |
| |
| test results: |
| 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. 15). The economizer will go to the full open posi- tion. The
8.Adjust mechanical linkage, if necessary, for correct po- sitioning. It may be necessary to remove the ®lters to adjust the linkage.
9.Remove the jumper from around the contacts of the OAT if installed in Step 6. Remove the jumper from termi- nals 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, damp- ers 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 GTAC II; Module 5; Charging, Recovery, Recycling, and Reclamation section for charging methods and procedures. Unit panels must be in place when unit is oper- ating during charging procedure.
NOTE: Do not use recycled refrigerant as it may contain contaminants.
A. No Charge
Use standard evacuating techniques. After evacuating system, weigh in the speci®ed amount of refrigerant (refer to Table 1).
B. Low Charge Cooling
Using cooling charging chart (see Fig. 30), add or remove re- frigerant until conditions of the chart are met. Note that charg- ing 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 ®nd 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
X. FILTER DRIER
Replace whenever refrigerant system is exposed to atmosphere.
XI. PROTECTIVE DEVICES
A. Compressor Protection
Overtemperature
Each compressor has an internal protector to protect it against excessively high discharge gas temperatures.
Overcurrent
Each compressor has internal line break motor protection, except circuit no. 1 on the 559F300 unit. Compressor no. 1 on the 559F300 unit uses an electronic module, located with the compressor junction box, to provide motor protec- tion. This electronic module monitors winding and discharge temperatures. If these temperatures reach the trip values, the module interrupts the control line and causes the com- pressor to switch off.
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