Bryant Heating and Cooling System Gas Furnace 986T Maintenance

The Bryant Heating and Cooling System Gas Furnace 986T Maintenance is a quick step by step procedure that ensures the quality performance of your machine. Remove risks by following the safety precautions in the form.

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04/26/2021

Bryant Heating and Cooling System Gas Furnace 986T Maintenance

WARNING: FIRE OR EXPLOSION HAZARD Failure to follow this warning could result in personal injury, death and/or property damage. Never store flammable or combustible materials on, near, or in contact with the furnace, such as:

Spray or aerosol cans, rags, brooms, dust mops, vacuum cleaners, or other cleaning tools.

Soap powders, bleaches, waxes or other cleaning compounds, plastic or plastic containers, gasoline, kerosene, cigarette lighter fluid, dry cleaning fluids, or other volatile fluids.

Paint thinners and other painting compounds, paper bags, or other paper products. Exposure to these materials could lead to corrosion of the heat exchangers.

For continuing high performance and to minimize possible furnace failure, periodic maintenance must be performed on this furnace. Consult your local dealer about proper frequency of maintenance and the availability of a maintenance contract.

WARNING: ELECTRICAL SHOCK AND FIRE HAZARD Failure to follow this warning could result in personal injury, death, and/or property damage. Turn off the gas and electrical supplies to the furnace and install lockout tag before performing any maintenance or s

WARNING: CARBON MONOXIDE POISONING AND FIRE HAZARD Failure to follow this warning could result in personal injury, death and/or property damage. Never operate furnace without a filter or filtration device installed. Never operate a furnace with filter or

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:

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

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

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

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

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

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.

Cleaning and/or Replacing Air Filter

The air filter type may vary depending on the application or orientation. The filter is external to the furnace casing. There are no provisions for an internal filter with this furnace. See “Filter Arrangement” under the “Installation” section of this man

WARNING: CARBON MONOXIDE POISONING AND FIRE HAZARD Failure to follow this warning could result in personal injury, death and/or property damage. Never operate furnace without a filter or filtration device installed. Never operate a furnace with filter or

NOTE: If the filter has an airflow direction arrow, the arrow must point toward the blower. To clean or replace filters, proceed as follows:

WARNING: ELECTRICAL SHOCK, FIRE OR EXPLOSION HAZARD Failure to follow this warning could result in personal injury or death, or property damage. Before installing, modifying, or servicing system, main electrical disconnect switch must be in the OFF positi

Turn off electrical supply to furnace.

Remove filter cabinet door.

Slide filter out of cabinet

If equipped with permanent, washable filter, clean filter by spraying cold tap water through filter in opposite direction of airflow. Rinse filter and let dry. Oiling or coating of the filter is not recommended.

If equipped with factory specified disposable media filter, replace only with a factory specified media filter of the same size.

Slide filter into cabinet.

Replace filter cabinet door.

Turn on electrical supply to furnace.

Blower Motor and Wheel Maintenance

The inducer and blower motors are pre--lubricated and require no additional lubrication. These motors can be identified by the absence of oil ports on each end of the motor.

The following items should be performed by a qualified service technician. Clean blower motor and wheel as follows:

Turn off electrical supply to furnace.

Remove blower door.

All factory wires can be left connected, but field thermostat and accessory wiring may need to be disconnected depending on their length and routing.

If the vent and combustion air pipe passes through the blower compartment, it will be necessary to remove the pipes from the blower compartment

Disconnect the vent and combustion air pipe by:

Loosen the clamps on the vent couplings and combustion air pipe external to the furnace.

Separate the pipes from the couplings and move them aside.

Loosen the clamps on the vent couplings and combustion air pipe located on the blower shelf.

Separate the pipes from the blower compartment and set aside.

Remove the couplings from the pipe adapters and set aside.

After servicing the blower, reverse steps a through e

Tighten all clamps 15 lb --in.

See Fig. 60 For Steps 5 through 14.

Remove screws securing blower assembly to blower shelf and slide blower assembly out of furnace. Detach ground wire and disconnect blower motor harness plugs from blower motor.

NOTE: Blower wheel is fragile. Use care

Clean blower wheel and motor by using a vacuum with soft brush attachment. Be careful not to disturb balance weights (clips) on blower wheel vanes. Do not bend wheel or blades as balance will be affected.

If greasy residue is present on blower wheel, remove wheel from the blower housing and wash it with an appropriate degreaser. To remove wheel:

Mark blower wheel location on shaft before disassembly to ensure proper reassembly.

Loosen setscrew holding blower wheel on motor shaft

NOTE: Mark blower mounting arms and blower housing so each arm is positioned at the same hole location during reassembly.

Mark blower wheel orientation and cutoff plate location to ensure proper reassembly

Remove screws securing cutoff plate and remove cutoff plate from housing.

Remove bolts holding motor mounts to blower housing and slide motor and mounts out of housing.

Remove blower wheel from housing.

Clean wheel per instructions on degreaser cleaner. Do not get degreaser in motor.

Reassemble motor and blower wheel by reversing items 7b through 7f. Ensure wheel is positioned for proper rotation.

Torque motor mounting bolts to 40 +/-- 10 lb--in. when reassembling.

Torque blower wheel set screw to 160 +/-- 20 lb--in. when reassembling.

Verify that blower wheel is centered in blower housing and set screw contacts the flat portion of the motor shaft. Loosen set screw on blower wheel and reposition if necessary

Spin the blower wheel by hand to verify that the wheel does not rub on the housing.

Reinstall blower assembly in furnace.

Reinstall 2 screws securing blower assembly to blower deck.

Reconnect blower leads to furnace control. Refer to furnace wiring diagram, and connect thermostat leads if previously disconnected.

NOTE: Be sure to attach ground wire and reconnect blower harness plugs to blower motor.

WARNING: ELECTRICAL OPERATION HAZARD Failure to follow this warning could result in personal injury or death. Blower door switch opens 115--v power to control. No component operation can occur unless switch is closed. Caution must be taken when manually c

Downflow or horizontal furnaces with vent pipe through furnace only:

Install and connect short piece of vent pipe inside furnace to existing vent.

Connect vent connector to vent elbow.

Turn on electrical supply. If outdoor temperature is below 70_F, turn off circuit breaker to outdoor unit before running furnace in the cooling cycle. Turn outdoor circuit breaker on after completing cooling cycle. (See Fig. 34.) Manually close blower doo

NOTE: If R--W/W1 thermostat terminals are jumpered at the time blower door switch is closed, blower will run for 90 sec before beginning a heating cycle.

Perform component self--test as shown at the bottom of the SERVICE label, located on the control door.

Verify blower is rotating in the correct direction

If furnace is operating properly, RELEASE BLOWER DOOR SWITCH. Remove any jumpers or reconnect any disconnected thermostat leads. Replace blower door.

Turn on gas supply and cycle furnace through one complete heating cycle. Verify the furnace temperature rise as shown in Adjustments Section. Adjust temperature rise as shown in Adjustments Section.

Cleaning Burners and Flame Sensor

The following items must be performed by a qualified service technician. If the burners develop an accumulation of light dirt or dust, they may be cleaned by using the following procedure:

NOTE: Use a back-up wrench on the gas valve to prevent the valve from rotating on the manifold or damaging the mounting to the burner assembly.

WARNING:ELECTRICAL SHOCK AND FIRE HAZARD Failure to follow this warning could result in personal injury, death, and/or property damage. Turn off the gas and electrical supplies to the furnace and install lockout tag before performing any maintenance or se

Refer to Fig. 61.

Disconnect power at external disconnect, fuse or circuit breaker.

Turn off gas at external shut-off or gas meter.

Remove control door and set aside.

Turn electric switch on gas valve to OFF.

Disconnect the gas pipe from gas valve and remove pipe from the furnace casing.

Disconnect the connector harness from gas valve (Modulating only) or remove individual wires from terminals on gas valve (All other models).

Disconnect Hot Surface Igniter (HSI) wires from HSI.

Disconnect Flame Sensor wire from Flame Sensor

Support the manifold and remove the 4 screws that secure the manifold assembly to the burner assembly and set aside. Note the location of the green/yellow wire and ground terminal

Inspect the orifices in the manifold assembly for blockages or obstructions. Remove orifice and clean or replace orifice.

Remove the four screws that attach the top plate of the casing to the furnace.

Raise top plate up slightly and prop it up with a small piece of wood or folded cardboard.

Support the burner assembly and remove the screws that attach the burner assembly to the heat exchanger cell panel.

Remove wires from both rollout switches.

Slide one--piece burner out of slots on sides of burner assembly.

Remove the flame sensor from the burner assembly.

(Optional) Remove the Hot Surface Igniter (HSI) and bracket from the burner assembly.

Check igniter resistance. Nominal resistance is 40 to 70 ohms at room temperature and is stable over the life of the igniter.

Clean burner with a brush and a vacuum

Clean the flame sensor with fine steel wool (0000 grade). Do not use sand paper or emery cloth.

To reinstall burner assembly:

Install the Hot Surface Igniter (HSI) and bracket in burner assembly.

Install flame sensor on burner.

Align the edges of the one-piece burner with the slots in the burner assembly and slide the burners forward until they are fully seated in the burner assembly.

Align the orifices in the manifold assembly with the support rings on the end of the burner.

Insert the orifices in the support rings of the burners

NOTE: If manifold does not fit flush against the burner, do not force the manifold on the burner assembly. The burners are not fully seated forward in the burner assembly. Remove the manifold and check burner positioning in the burner assembly assembly be

Attach the green/yellow wire and ground terminal to one of the manifold mounting screws.

Install the remaining manifold mounting screws.

Check the igniter alignment. See Fig. 55, 56 and 61.

Attach the wires to the roll-out switches.

Align the burner assembly with the openings in the primary cell inlet panel and attach the burner assembly to the cell panel.

Connect the wire for the flame sensor.

Connect the wire for the Hot Surface Igniter.

NOTE: Use propane-resistant pipe dope to prevent leaks. Do not use Teflon tape.

Install the gas pipe to the gas valve.

WARNING:FIRE OR EXPLOSION HAZARD Failure to follow this warning could result in personal injury, death, and/or property damage. Never purge a gas line into a combustion chamber. Never test for gas leaks with an open flame. Use a commercially available soa

Check for gas leaks with a commercially available soap solution made specifically for the detection of leaks

Turn gas on at electric switch on gas valve and at external shut-off or meter

Turn power on at external disconnect, fuse or circuit breaker

Run the furnace through two complete heating cycles to check for proper operation

Install control door when complete

Servicing Hot Surface Igniter

The igniter does NOT require annual inspection. Check igniter resistance before removal. Refer to Fig. 55, 56 and 61.

Turn off gas and electrical supplies to furnace.

Remove control door.

Disconnect igniter wire connection.

Check igniter resistance. Igniter resistance is affected by temperature. Only check resistance when the igniter is at room temperature.

a. Using an ohm meter, check resistance across both igniter leads in connector.

b. Cold reading should be between 40 ohms and 70 ohms. Resistance reading will increase as igniter temperature increases.

Remove igniter assembly.

a. Using a 1/4--in. driver, remove the two screws securing the igniter mounting bracket to the burner assembly (See Fig. 61 .)

b. Carefully withdraw the igniter and bracket assembly through the front of the burner assembly without striking the igniter on surrounding parts.

c. Inspect igniter for signs of damage or failure.

d. If replacement is required, remove the screw that secures the igniter on igniter bracket and remove the igniter.

To replace igniter and bracket assembly, reverse items 5a through 5d

Reconnect igniter harness to the igniter, dressing the igniter wires to ensure there is no tension on the igniter itself. (See Fig. 61.)

Turn on gas and electrical supplies to furnace.

Verify igniter operation by initiating control board self--test feature or by cycling thermostat.

Replace control door.

Flushing Collector Box and Drainage System

WARNING: ELECTRICAL SHOCK AND FIRE HAZARD Failure to follow this warning could result in personal injury, death, and/or property damage. Turn off the gas and electrical supplies to the furnace and install lockout tag before performing any maintenance or s

Turn off gas and electrical supplies to furnace

Remove control door.

Disconnect pressure switch tube from pressure switch port.

NOTE: Ensure the pressure switch tube disconnected from the pressure switch is higher than the collector box opening or water will flow out of tube

Remove the collector box plug from the top port on the upper corner of the collector box. (See Fig. 57)

Attach a funnel with a flexible tube to port on the collector box.

Flush inside of collector box with water until discharge water from condensate trap is clean and runs freely

Repeat steps 4 thru 6 with middle plug on upper corner of collector box.

Remove the pressure switch tube from the collector box

NOTE: Do NOT blow into tube with tube connected to the pressure switch.

Clean pressure switch port on collect box with a small wire. Shake any water out of pressure switch tube

Reconnect tube to pressure switch and pressure switch port.

Remove the relief tube from the port on the collector box and the trap.

Clean the relief port on collect box and the trap with a small wire. Shake any water out of the tube.

Reconnect relief tube to trap and collector box ports.

Cleaning Condensate Drain and Trap

NOTE: If the condensate trap is removed, a new gasket between the trap and collector box is required. Verify a condensate trap gasket is included in the service kit or obtain one from your local distributor

Disconnect power at external disconnect, fuse or circuit breaker

Turn off gas at external shut-off or gas meter.

Remove control door and set aside.

Turn electric switch on gas valve to OFF.

Disconnect external drain from condensate drain elbow or drain extension pipe inside the furnace and set aside

Disconnect the condensate trap relief hose from collector box port and condensate trap

NOTE: If condensate has a heat pad attached to the trap, trace the wires for the pad back to the connection point and disconnect the wires for the heat pad.

Remove the screw that secures the condensate trap to the collector box, remove the trap and set aside.

Remove the trap gasket from the collector box if it did not come off when the trap was removed.

Discard the old trap gasket

Rinse condensate trap in warm water until trap is clean

. Flush condensate drain lines with warm water. Remember to check and clean the relief port on the collector box.

Shake trap dry.

Clean port on collector box with a small wire.

To re-install Condensate Drain and Trap:

Remove adhesive backing from condensate trap gasket

Install gasket on collector box

Align the condensate trap with the drain opening on the collector box and secure the trap with the screw

Attach the relief hose to the relief port on the condensate trap and collector box.

Secure tubing to prevent any sags or traps in the tubing

Connect condensate drain elbow or drain extension elbow to the condensate trap

Connect the leads of the condensate heat pad (if used)

Connect external drain piping to the condensate drain elbow or drain extension pipe.

Turn gas on at electric switch on gas valve and at external shut-off or meter

Turn power on at external disconnect, fuse or circuit breaker

Run the furnace through two complete heating cycles to check for proper operation

Install control door when complete

Checking Heat Pad Operation (If Applicable)

In applications where the ambient temperature around the furnace is 32_F or lower, freeze protection measures are required. If this application is where heat tape has been applied, check to ensure it will operate when low temperatures are present.

NOTE: The Heat Pad, when used, should be wrapped around the condensate drain trap. There is no need to use heat tape within the furnace casing. Most heat tapes are temperature activated, and it is not practical to verify the actual heating of the tape. Ch

Check for signs of physical damage to heat tape such as

nicks

cuts

abrasions

gnawing by animals, etc.

Check for discolored heat tape insulation. If any damage or discolored insulation is evident, replace heat tape.

Cleaning Heat Exchangers

The following items must be performed by a qualified service technician.

Primary Heat Exchangers

If the heat exchangers get an accumulation of light dirt or dust on the inside, they may be cleaned by the following procedure:

NOTE: If the heat exchangers get a heavy accumulation of soot and carbon, both the primary and secondary heat exchangers should be replaced rather than trying to clean them thoroughly due to their intricate design. A build--up of soot and carbon indicates

Turn off gas and electrical supplies to furnace.

WARNING: ELECTRICAL SHOCK, FIRE OR EXPLOSION HAZARD Failure to follow this warning could result in personal injury or death, or property damage. Before installing, modifying, or servicing system, main electrical disconnect switch must be in the OFF positi

WARNING:ELECTRICAL SHOCK AND FIRE HAZARD Failure to follow this warning could result in personal injury, death, and/or property damage. Turn off the gas and electrical supplies to the furnace and install lockout tag before performing any maintenance or se

Remove control door

Disconnect wires or connectors to

flame rollout switch

gas valve

igniter

flame sensor

Using backup wrench, disconnect gas supply pipe from furnace gas control valve.

Remove two screws attaching top filler plate and rotate upwards to gain access to screws attaching burner assembly to cell panel.

Remove screws attaching burner assembly to cell panel. (See Fig. 61.)

NOTE: Burner cover, manifold, gas valve, and burner assembly should be removed as one assembly.

Clean heat exchanger openings with a vacuum and a soft brush. (See Fig. 58.)

NOTE: After cleaning, inspect the heat exchangers to ensure they are free of all foreign objects that may restrict flow of combustion products.

Reverse items 6 through 1 for reassembly.

Refer to furnace wiring diagram and reconnect wires to

flame rollout switch

gas valve

igniter

flame sensor

Turn on gas and electrical supplies to furnace.

Check furnace operation through 2 complete heat operating cycles. Look at burners. Burner flames should be clear blue, almost transparent. (See Fig. 59.)

Check for gas leaks.

WARNING:FIRE OR EXPLOSION HAZARD Failure to follow this warning could result in personal injury, death, and/or property damage. Never purge a gas line into a combustion chamber. Never test for gas leaks with an open flame. Use a commercially available soa

Replace main furnace door.

Secondary Heat Exchangers

The condensing side (inside) of the secondary heat exchanger CANNOT be serviced or inspected without complete removal of the heat exchanger assembly. Detailed information on heat exchanger removal can be obtained from your Distributor.

Wiring Diagrams

See Fig. 63 for the Deluxe 4--Way Multipoise Furnace wiring diagrams.

WINTERIZATION

CAUTION: UNIT AND PROPERTY DAMAGE HAZARD Failure to follow this caution may result in unit component or property damage. If the furnace is installed in an unconditioned space where the ambient temperatures may be 32_ F (0_ C) or lower, freeze protection m

Since the furnace uses a condensing heat exchanger, some water will accumulate in the unit as a result of the heat transfer process. Therefore, once it has been operated, it cannot be turned off and left off for an extended period of time when temperature

CAUTION:UNIT COMPONENT DAMAGE HAZARD Failure to follow this caution may result in damage to the furnace and other property damage. Do not use ethylene glycol (automotive antifreeze coolant or equivalent). Failure of plastic components may occur.

Obtain propylene glycol (RV/swimming pool antifreeze or equivalent).

Turn off gas and electrical supplies to your furnace.

Remove furnace control door.

Remove the top unused rubber plug from the port on the collector box opposite the condensate trap. See Fig. 57.

Connect a field supplied 3/8--in. (9.5--mm) ID tube to the open port on the collector box

Insert a field supplied funnel into the tube.

Pour 1 quart of anti--freeze solution into the funnel/tube. Antifreeze should run through the inducer housing, overfill condensate trap and flow to an open drain

Remove the middle unused rubber plug from the port on the collector box opposite the condensate trap. See Fig. 57

Repeat Steps 5 through 8

If a condensate pump is used, check with pump manufacturer to verify pump is safe for use with antifreeze used. Allow pump to start and pump anti--freeze to open drain.

Replace main door

. When furnace is re--started, flush condensate pump with clear water to check for proper operation before re--starting furnace