Bryant 312AAV/JAV Check Safety Controls, Checklist, Amp. Draw Check with Ammeter

Table 14 – 2-Stage Furnace Blower OFF delay Setup Switch

DESIRED HEATING MODE	SETUP SWITCH	SETUP SWITCH
BLOWER OFF DELAY (SEC.)	SW---2	SW---3
90	OFF	OFF
120	OFF	ON
150	ON	OFF
180	ON	ON

THERMOSTAT SUBBASE TERMINALS WITH THERMOSTAT REMOVED (ANITICIPATOR, CLOCK, ETC.,

MUST BE OUT OF CIRCUIT.)

HOOK-AROUND AMMETER

R Y W G

10 TURNS

FROM UNIT 24-V

CONTROL TERMINALS

EXAMPLE:	5.0 AMPS ON AMMETER	=	0.5 AMPS FOR THERMOSTAT
	10 TURNS AROUND JAWS		ANTICIPATOR SETTING

A96316

Fig. 50 - Amp. Draw Check with Ammeter

Step 4 — 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(es)

This control shuts off combustion system and energizes air-circulating blower motor, if furnace overheats. By us- ing 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 draft safeguard switch.

The purpose of this control is to cause the safe shutdown of the furnace during certain blocked vent conditions.

a.Verify vent pipe is cool to the touch.

b.Disconnect power to furnace and remove vent connector from furnace vent elbow.

c.Restore power to furnace and set room thermostat above room temperature.

d.After normal start-up, allow furnace to operate for 2 minutes, then block vent elbow in furnace 80% of vent area with a piece of flat sheet metal.

e.Furnace should cycle off within 2 minutes. If gas does not shut off within 2 minutes, determine reason draft safe-

guard switch did not function properly and correct condi- tion.

f.Remove blockage from furnace vent elbow.

g.Switch will auto-reset when it cools.

h.Re-install vent connector.

NOTE: Should switch remain open longer than 3 minutes, furnace control board will lockout the furnace for 3 hours. To reset furnace control board, turn thermostat below room temperature or from HEAT to OFF and turn 115-v power OFF, then back ON.

3.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 ig- niter should NOT glow and control diagnostic light flashes a status code 32. If hot surface igniter glows when inducer motor is disconnected, shut down furnace imme- diately.

e.Determine reason pressure switch did not function prop- erly and correct condition.

f.Turn off 115-v power to furnace.

g.Reconnect inducer motor wires, replace outer 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.

Step 5 — Checklist

1.Put away tools and instruments. Clean up debris.

2.Verify that switches for LHT and OFF-DELAY are blower OFF-DELAY are selected as desired.

3.Verify that blower and burner access doors are properly in- stalled.

4.Cycle test furnace with room thermostat.

5.Check operation of accessories per manufacturer￿fs in- structions.

6.Review User’s Guide with owner.

7.Attach literature packet to furnace.

312AAV

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