Electrical Inspection/Repair - Northwind MAC1211 Engineering, Installation And Service Manual

CONDENSER FAN CYCLE CONTROL
1. Disconnect unit from power; unplug power cord.
2. Remove right side panel of unit.
3. Remove and mark 2 wires on terminals of cycle switch to assure correct reconnection.
4. Using a 9/16 flare tube wrench, remove switch from schrader access valve. A small, DeMinimus
release of refrigerant may occur when components are separated. This is normal.
5. Install new fan cycle switch and use reverse order to finish process.
PANEL MOUNTED RELAYS, CONTACTORS, TIME DELAY TRANSFORMER
1. Disconnect power to unit, unplug power cord.
2. Remove 4 screws on the electrical cover located on the unit's lower back panel.
3. Select control to be replaced, carefully marking wires for reattaching to new control.
4. Remove control from panel; reinstall new control.
5. Reconnect wires; reinstall panel cover.
CAUTION: DISCONNECT POWER TO UNIT PRIOR TO INSPECTION
1. Inspection of thermostat: Check for continuity across terminals 1 and 2, (C-12, C-21) and terminals 4 and 5 on C-17, when
calling for full cooling (dial full clockwise) above 65°F. If continuity is broken across the terminals, replace the thermostat.
2. Inspection of fan speed switch:
There should be continuity across the above terminals. If none, replace the switch.
3. Inspection of tank full switch: Depress the microswitch lever to check for continuity. If there is no continuity between
common and normally open terminals, replace the switch.
4. Inspection of high pressure switch: Check for continuity across terminals 1 and 2 of the high pressure switch. At normal
pressure when the unit is not operating, there is continuity across the two terminals. If continuity is interrupted across the
terminals, replace the high pressure switch.
5. Inspection of compressor motor: Measure the resistance across the terminals of the compressor motor.
Replace compressor when the resistance is not at these stated values.
6. Inspection of compressor overload : Check for continuity across overload's two terminals. At normal room temperatures,
there is continuity across the two terminals. If no continuity exists, replace the overload.
7. Inspection of compressor and fan motor capacitors: Before and after the test, always short across the two terminals to
discharge electric charge. Set the ohmmeter to 100 OHMS range and place its two probes against the two terminals of the
capacitor. At first, the ohmmeter should indicate zero OHMS, then the meter reading should gradually approach infinity. If
the ohmmeter shows infinity from the outset or the meter reading does not move from zero OHMS, replace the capacitor.
INSPECTION/REPAIR OF ELECTRICAL SYSTEM
SWITCH POSITION
High Speed
Low Speed
Resistance between C-R at 70°F approximately 0.65 OHMS ± 10%
Resistance between C-S at 70°F approximately 4.50 OHMS ± 10%
CONDUCTING TERMINALS
Center & Left Terminal
Center & Right Terminal
17
Condenser Fan
Cycle Switch
Electrical Panel
Back View of Switch