Electrical Maintenance 8-22
HIGH WATER TEMPERATURE SWITCH
MT µP-IV NOTE: On units with an Emergency Bypass switch, the high water temperature switch operates ONLY when
emergency operation is selected to bypass microprocessor control.
The high water temperature switch will close and open the reset switch if the coolant temperature is greater than 104 C. Use a
continuity tester to check the switch. Use a coolant temperature gauge to check the coolant system temperature.
Switch Test
1. Remove wire 20A from the high water temperature switch.
2. Operate the unit until it reaches normal operating temperature of 82 C. There should be no continuity from the switch to
ground.
3. If the engine becomes overheated and reaches 104 C, the switch should have continuity to ground.
4. Replace a defective switch.
CONDENSER AND EVAPORATOR FAN ROTATION (ELECTRIC STANDBY OPERATION)
The condenser and evaporator fans are belt driven. On electric standby operation, check for correct fan rotation by placing a small
cloth or sheet of paper against the condenser fan grille on the front of the unit. Correct rotation will hold the cloth or paper against
the grille. Improper rotation will blow the cloth or paper away from the grille. To correct improper condenser fan rotation, reverse
any two power cord leads at the power cord. (DO NOT move the ground wire which is normally GREEN.)
Correct Unit Airflow
1. Condenser Air In
2. Condenser Air Out
3. Evaporator Air In
4. Evaporator Air Out
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