Thermo Products MDA1-100N, MDA1-50N, MHA1-75N, MHA1-100N, MHA1-50N, MDA1-75N Blower and Control Panel

All installations and services must be performed by qualified service personnel.

Anticipators for the cooling operation are generally pre-set by the thermostat manufacturer and require no adjustment.

5.Blower Motor Speed Wiring :

•TURN OFF THE ELECTRICAL POWER to the furnace before attempting to change blower speed wiring.

The blower motor is factory wired to the ignition control with standard heating and cooling speeds pre-selected.

When changing motor speeds, simply switch the wire from the needed speed to either the heating or cooling terminal as applicable on the module to obtain the desired airflow. The wires for the unused speeds should then be reconnected to the module in the “park” positions.

EAC - COMMON

HUMIDIFIER - COMMON

GREEN

	4
	3
	2
ON	1

120v 24v

GREENCAPACITOR

OPTIONAL FAN

DELAY SWITCHES

COMMON (WHITE)

MED-HIGH SPEED (YELLOW)

MED-LOW SPEED (BLUE)

LOW SPEED (RED)

HIGH SPEED (BLACK)

HUMIDIFIER EAC

PARK TERMINALS

FOR UNUSED

SPEEDS

		NOTE:
		MHA1-50,75,100,125
		MDA1-50,100
	TRANSFORMER	USE LOW SPEED FOR HEATING
TERMINAL COOLING SPEED
		MDA1-75,125
TERMINAL HEATING SPEED		USE MED-LOW SPEED FOR HEATING
		MHA/MDA1-50 HAS A
		3 SPEED MOTOR

Figure 8: Blower and Control Panel

The option switches on the W/R integrated control are used to determine the length of the heat delay-to-fan-on and delay –to-fan-off periods. The following tables show the time periods that will result from the various switch positions.

28