Bryant 120 instruction manual Service

!CAUTION

CUT HAZARD

Failure to follow this caution may result in personal injury.

Sheet metal parts may have sharp edges or burrs. Use care and wear appropriate protective clothing, safety glasses and gloves when handling parts and servicing furnaces.

The minimum maintenance on this furnace is as follows:

1.Check and clean air filter each month or more frequently if required. Replace if torn.

2.Check blower motor and wheel for cleanliness each heating and cooling season. Clean as necessary.

3.Check electrical connections for tightness and controls for proper operation each heating season. Service as necessary.

4.Inspect burner compartment before each heating season for rust, corrosion, soot or excessive dust. If necessary, have furnace and burner serviced by a qualified service agency.

5.Inspect the vent pipe/vent system before each heating season for rust, corrosion, water leakage, sagging pipes or broken fittings. Have vent pipes/vent system serviced by a qualified service agency.

6.Inspect any accessories attached to the furnace such as a humidifier or electronic air cleaner. Perform any service or maintenance to the accessories as recommended in the accessory instructions.

SERVICE

If status code recall is needed, briefly remove then reconnect one main limit wire to display last stored status code. On RED LED boards do not remove power or blower door before initiating status code recall.

LED CODE STATUS

CONTINUOUS OFF - Check for 115VAC at L1 and L2, and 24VAC at SEC-1 and SEC-2.

CONTINUOUS ON - Control has 24VAC power.

RAPID FLASHING - Line voltage (115VAC) polarity reversed. If twinned, refer to twinning kit instructions.

EACH OF THE FOLLOWING STATUS CODES IS A TWO DIGIT NUMBER WITH THE FIRST DIGIT DETERMINED BY THE NUMBER OF SHORT FLASHES AND THE SECOND DIGIT BY THE NUMBER OF LONG FLASHES.

312A

11NO PREVIOUS CODE - Stored status code is erased automatically after 72 hours. On RED LED boards stored status codes can also be erased when power

(115 VAC or 24 VAC) to control is interrupted.

12BLOWER ON AFTER POWER UP (115 VAC or 24 VAC) -Blower runs for the selected blower off-delay time, if unit is powered up during a call for heat (R-W/W1 closed) or (R-W/W1) opens during blower on-delay.

13LIMIT CIRCUIT LOCKOUT - Lockout occurs if a limit, draft safeguard, flame rollout, or blocked vent switch (if used) is open longer than 3 minutes.

- Control will auto reset after three hours. - Refer to #33.

14IGNITION LOCKOUT - Control will auto-reset after three hours. Refer to #34.

21GAS HEATING LOCKOUT - Control will NOT auto reset.

Check for: - Mis-wired gas valve - Defective control (valve relay)

22ABNORMAL FLAME-PROVING SIGNAL - Flame is proved while gas valve is de- energized. Inducer will run until fault is cleared. Check for:

- Leaky gas valve - Stuck-open gas valve

23PRESSURE SWITCH DID NOT OPEN Check for: - Obstructed pressure tubing

-Pressure switch stuck closed

24SECONDARY VOLTAGE FUSE IS OPEN Check for: - Short circuit in secondary voltage (24VAC) wiring.

31HIGH-HEAT PRESSURE SWITCH OR RELAY DID NOT CLOSE OR REOPENED Control relay may be defective, refer to status code #32

COMPONENT TEST

To initiate the component test sequence, shut OFF the room thermostat or disconnect the "R" thermostat lead. Briefly short the TEST/TWIN terminal to the "Com 24V" terminal. Status LED will flash last status code and then turn ON the inducer motor. The inducer motor will start in HIGH speed and remain on HIGH speed until the end of the test then shift to LOW speed for 7 to 15 seconds. The hot surface igniter, blower motor LO HEAT speed, blower motor HI HEAT speed, and blower motor COOL speed will be turned ON for 10-15 seconds each. Gas Valve and Humidifier will not be turned on. When the blower is turned OFF the inducer will be switched to low-speed for 10 seconds.

32LOW-HEAT PRESSURE SWITCH DID NOT CLOSE OR REOPENED - If open longer than five minutes, inducer shuts off for 15 minutes before retry. If opens during blower on-delay

period, blower will come on for the selected blower off-delay. Check for:

- Excessive wind	- Restricted vent	- Defective inducer motor
- Proper vent sizing	- Defective pressure switch	- Low inducer voltage (115 VAC)
- Inadequate combustion air supply		- Low inlet gas pressure (if LGPS used)
- Disconnected or obstructed pressure tubing

33LIMIT CIRCUIT FAULT - Indicates a limit, draft safeguard, flame rollout, or blocked vent switch (if used) is open. Blower will run for 4 minutes or until open switch remakes whichever is longer. If open longer than 3 minutes, code changes to lockout #13. If open less than 3 minutes status code #33 continues to flash until blower shuts off. Flame rollout

switch and BVSS require manual reset. Check for: - Dirty filter or restricted duct system

- Defective blower motor or capacitor	- Proper vent sizing	- Restricted vent
- Defective switch or connections	- Loose blower wheel	- Excessive wind
- Inadequate combustion air supply (Flame Roll-out Switch open).

34IGNITION PROVING FAILURE - Control will try three more times before lockout #14 occurs.

If flame signal lost during blower on-delay period, blower will come on for the selected blower off-delay. Check for: - Oxide buildup on flame sensor (clean with fine steel wool) - Proper flame sense microamps (.5 microamps D.C. min., 4.0 - 6.0 nominal)

- Manual valve shut-off	- Control ground continuity
- Gas valve defective or gas valve turned off	- Low inlet gas pressure
- Inadequate flame carryover or rough ignition	- Defective Hot Surface Ignitor

-Flame sensor must not be grounded

-Green/Yellow wire MUST be connected to furnace sheet metal

43 LOW-HEAT PRESSURE SWITCH OPEN WHILE HIGH-HEAT PRESSURE SWITCH IS

CLOSED - Check for:	- Disconnected or obstructed pressure tubing
- Mis-wired pressure switches	- Low-heat pressure switch stuck open
- Low inlet gas pressure (if LGPS used)

45CONTROL CIRCUITRY LOCKOUT Auto-reset after one hour lockout due to;

- Gas valve relay stuck open	- Flame sense circuit failure	- Software check error
Reset power to clear lockout. Replace control if status code		repeats.

327598-101 REV. C

A04210

Fig. 57 - Service Label

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