ICP A3 Series, Service And Technical Support Manual

SERVICE AND TECHNICAL SUPPORT MANUAL

Gas Furnace: (F/G)9MVE

Specifications  subject to change without notice.

14

440 04 4801 03

Adjust Thermostat Heat Anticipator

a. Mechanical thermostat.  Set thermostat heat

anticipator to match the amp. draw of the electrical

components in the R

−

W/W1 circuit. Accurate amp.

draw readings can be obtained at the wires normally

connected to thermostat subbase terminals, R and W.

The thermostat anticipator should NOT be in the

circuit while measuring current.

(1.) Set SW1

−

2 switch on furnace control board to

ON.

(2.) Remove thermostat from subbase or from wall.
(3.) Connect an amp. meter as shown in 

Figure 6

across the R and W subbase terminals or R and

W wires at wall.

(4.) Record amp. draw across terminals when

furnace is in low heat and after blower starts.

(5.) Set heat anticipator on thermostat per thermostat

instructions and install on subbase or wall.

(6.)  Turn SW1

−

2 switch OFF.

(7.) Install blower door.

b. Electronic thermostat: Set cycle rate for 3 cycles per

hr.

Figure 6

Amp. Draw Check with Ammeter

A96316

R Y W G

10 TURNS

THERMOSTAT SUBBASE

TERMINALS WITH

THERMOSTAT REMOVED

(ANITICIPATOR, CLOCK, ETC.,

MUST BE OUT OF CIRCUIT.)

HOOK-AROUND

AMMETER

EXAMPLE: 5.0 AMPS ON AMMETER

10 TURNS AROUND JAWS

=  0.5 AMPS FOR THERMOSTAT

     ANTICIPATOR SETTING

FROM UNIT 24-V

CONTROL TERMINALS

Check Safety Controls

The flame sensor, gas valve, and pressure switch were all

checked in the Start

−

up procedure section as part of normal

operation.

1. Check Main Limit Switch 

This control shuts off combustion system and energizes

air

−

circulating blower motor, if furnace overheats. By

using this method to check limit control, it can be

established that limit is functioning properly and will

operate if there is a restricted return

−

air supply or motor

failure. If limit control does not function during this test,

cause must be determined and corrected.
a. Run furnace for at least 5 minutes.
b. Gradually block off return air with a piece of

cardboard or sheet metal until the limit trips.

c. Unblock return air to permit normal circulation.

d. Burners will re

−

light when furnace cools down.

2. Check Pressure Switch(es) 

This control proves operation of the draft inducer blower.
a. Turn off 115

−

v power to furnace.

b. Disconnect inducer motor lead wires from wire

harness.

c. Turn on 115

−

v power to furnace.

d. Set thermostat to “call for heat” and wait 1 minute.

When pressure switch is functioning properly, hot

surface igniter should 

NOT 

glow and control

diagnostic light flashes a status code 3. If hot surface

igniter glows when inducer motor is disconnected,

shut down furnace immediately.

e. Determine reason pressure switch did not function

properly and correct condition.

f. Turn off 115

−

v power to furnace.

g. Reconnect inducer motor wires, replace door, and

turn on 115

−

v power.

h. Blower will run for 90 seconds before beginning the

call for heat again.

i. Furnace should ignite normally.

Checklist

1. Put away tools and instruments. Clean up debris.
2. Verify that switches SW1

−

1 and SW1

−

6 are OFF

and

other setup switches are set as desired. Verify that

switches SW1

−

7 and SW1

−

8 for the blower OFF DELAY

are set as desired per 

Table 4

.

3. Verify that blower and control doors are properly

installed.

4. Cycle test furnace with room thermostat.
5. Check operation of accessories per manufacturer’s

instructions.

6. Review Home Owner’s Information with owner.
7. Attach literature packet to furnace.