Thermo Products Thermo Pride Furnace MHA1-75N User's Manual | Page 31

Thermo Products Furnace User's Manual - Thermo Pride Furnace MHA1-75N.
Download
Page  of 61
4.8, 1781 votes
background image

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

28 

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. 

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 fol owing 
tables show the time periods that will result from the various switch positions. 

SPEEDS

PARK TERMINALS

FOR UNUSED

234
1

ON

GREEN

12

0v

24

v

GREEN

CAPACITOR

TERMINAL HEATING SPEED

TERMINAL COOLING SPEED

TRANSFORMER

NOTE:
MHA1-50,75,100,125
MDA1-50,100
USE LOW SPEED FOR HEATING

MDA1-75,125 
USE MED-LOW SPEED FOR HEATING

MHA/MDA1-50 HAS A 
3 SPEED MOTOR

HIGH SPEED (BLACK)

LOW SPEED (RED)

MED-LOW SPEED (BLUE)

MED-HIGH SPEED (YELLOW)

COMMON (WHITE)

OPTIONAL FAN 

DELAY SWITCHES

EAC

HUMIDIFIER

EAC - COMMON

HUMIDIFIER - COMMON

0.600784s