Armstrong Air Conditioning A97DSMV, Installation Instructions Manual

507029-03

Page 31 of 68

Issue 1622

NOTE:

Unit nameplate states maximum current draw.  See 

table for maximum over-current protection.

2.  Holes are on both sides of the furnace cabinet to 

facilitate wiring.

3.  Install  a  separate  (properly  sized)  disconnect  switch 

near the furnace so that power can be turned off for 

servicing.

4.  Before connecting the thermostat check to make sure 

the wires will be long enough for servicing at a later date.  

Make sure that the thermostat wire is long enough to 

facilitate future removal of blower for service.

5.  Complete the wiring connections to the equipment.  Use 

the provided  unit wiring diagram and the field wiring 

diagram shown in Figure 40 and Table 11.  Use 18 

gauge wire or larger that is suitable for Class II rating 

for thermostat connections.

6.  Electrically ground the unit according to local codes or, 

in the absence of local codes, according to the current 

National Electric Code (ANSI/HFPA No. 70) for the 

USA and current Canadian Electric Code Part 1 (CSA 

standard C22.1) for Canada.  A green ground wire is 

provided in the field make up box.

7.  One line voltage “EAC” 1/4” spade terminal is provided 

on the furnace integrated control.  Any electronic air 

cleaner or other 120V accessory rated up to 

one amp

can be connected to this terminal with the neutral leg 

of the circuit being connected to one of the provided 

neutral terminals.  See Figure 45 for location of terminal.  

This terminal is energized when the indoor blower is 

operating.

8.  One line voltage “hum” 1/4” spade terminal is provided 

on the furnace integrated control.  Any humidifier rated 

up to one amp can be connected to this terminal with the 

neutral leg of the circuit being connected to one of the 

provided neutral terminals.  See Figure 46 for location 

of terminal.  This terminal is energized in the heating 

mode when the indoor blower is operating.

9.  One 24V “H” terminal is provided on the furnace 

integrated control terminal block.  Any humidifier rated 

up to 0.5 amp can be connected to this terminal with 

th ground leg of the circuit being connected to either 

ground or the “C” terminal.  See Figure 46 for location 

of terminal.

1.  The power supply wiring must meet Class I restrictions.  

Protected by either a fuse or circuit breaker, select circuit 

protection and wire size according to unit nameplate.

10.

Install the room thermostat according to the instructions 

provided with the thermostat

. 

See Table 11 for 

thermostat connections

. 

If the furnace is being matched 

with a heat pump

, 

refer to the instruction packaged with 

the dual fuel thermostat

.

Thermostat Selection 

The unit is designed to operate in a variable rate capacity 

mode using a two stage thermostat.  This unit will 

automatically adjust firing rate based upon thermostat cycle 

times. 

A Comfort Sync™ thermostat must be used in communicating 

applications. Refer to the instructions provided with the 

thermostat for installation, set up and operation. 

For optimal performance in non-communicating applications, 

a thermostat with adjustable settings for 1

st

 stage /2

nd

stage on/off differentials and adjustable stage timer is 

recommended. 

The Following two stage thermostat set-up is recommennded 

for optimal variable rate capacity mode:

First heat stage differential set to 

1/2 

to 1 degree F; second 

heat stage differential set to 

1/2 

or 1 degree F; second heat 

stage upstage timer disabled, or set to maximum (1 hr 

minimum).

Indoor Blower Speeds 

NOTE:

  When this unit is used with a Comfort Sync™ 

thermostat, proper indoor blower speed selections are made 

by the communicating thermostat

. 

1.  When the thermostat is set to “FAN ON”, the indoor 

blower will run continuously at 38% percent of the 

second stage cooling speed when there is no cooling 

or heating demand. 

2.  When the unit is running in the heating mode, the 

integrated control will automatically adjust the blower 

speed to match the furnace firing rate. This speed can  

be adjusted up or down by 7.5% or 15% using DIP 

switches 14 through 16 for the low heat speed and 17  

through 19 for the high heat speed. 

3.  When there is a cooling demand, the indoor blower will 

run on the cooling speed designated by the positions of 

DIP switches 8 through 11. 

NOTE:

  The discharge air temperature sensor is intended 

to be mounted downstream of the heat exchanger and a

i

r 

conditioning coil

. 

I

t must be placed in free airflow

, 

where 

other accessories (humidifiers

, 

UV lights etc.) will not 

interfere with its accuracy

. 

Wiring distance between the 

furnace and discharge air sensor should not exceed 10 ft

. 

when wired with 18 gauge thermostat wi

r

e

. 

Table 10