B. Checking and Adjusting Refrigerant Charge
The refrigerant system is fully charged with
NOTE: Adjustment of the refrigerant charge is not required unless the unit is suspected of not having the proper
A superheat charging label is attached to the inside of the compressor access door. The label includes a ``Superheat Charg- ing Table'' and a ``Required
An accurate superheat,
CAUTION: When evaluating the refrigerant charge, an indicated adjustment to the speci®ed factory charge must always be very minimal. If a substantial adjust- ment is indicated, an abnormal condition exists some- where in the cooling system, such as insufficient airflow across either coil or both coils.
Proceed as follows:
1.Remove caps from low- and
2.Using hoses with valve core depressors, attach low- and
3.Start unit in Cooling mode and let unit run until sys- tem pressures stabilize.
4.Measure and record the following:
a.Outdoor
b.Evaporator
c.
d.Suction
5.Using ``Superheat Charging Table,'' compare outdoor- air temperature (F db) with evaporator
6.Using ``Required
7.Compare actual
NOTE: If the problem causing the inaccurate readings is a refrigerant leak, refer to Check for Refrigerant Leaks section on page 23.
C. Indoor Air¯ow and Air¯ow Adjustments
CAUTION: For cooling operation, the recommended air¯ow is 350 to 450 cfm for each 12,000 Btuh of rated cooling capacity. For heating operation, the air¯ow must produce a temperature rise that falls within the range stamped on the unit rating plate.
Table 6 shows the temperature rise at various air¯ow rates. Tables
NOTE: Be sure that all supply- and
WARNING: Shut off gas supply then disconnect elec- trical power to the unit before changing blower speed. Electrical shock can cause personal injury or death.
Air¯ow can be changed by changing the lead connections of the blower motor.
Unit 588A two- or
For
The motor leads are
| |||
black = | high speed | black = high speed | |
blue | = | medium speed | red = low speed |
red | = low speed |
|
To change the speed of the blower motor, remove the fan mo- tor speed leg lead from the blower relay (BR). This wire is attached to terminal BM for
For
The motor leads are color coded as follows:
black | = high | black = high | |||
blue | = | jumper | blue | = | jumper |
orange = medium | red | = | low | ||
red | = low |
|
|
|
To change the speed of the blower motor, remove fan motor speed lead from the blower relay (BR) and replace with the lead for the desired blower motor speed. The motor speed lead is attached to terminal BM. Insulate removed lead end to avoid contact with chassis parts. On
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