Carrier 58MTA, 58MVP, 58MXA, 58MCA manual 3738, Combustion Area and Vent System

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When dirt, soot, scale, or rust is allowed to build up, your fur- nace can suffer a loss of efficiency and perform improperly. Accumulations on the main burners can result in firing out of normal sequence. This delayed ignition creates an alarmingly loud sound.

!CAUTION

If your furnace makes an especially loud noise when the main burners light, shut down your fur- nace and call your dealer. Failure to follow this caution would result in minor property damage.

To inspect the combustion area and vent system, you will need a flashlight. Refer to Fig. 3 or 4, and proceed as follows:

FURNACE AIR FILTER TABLE

AIR FILTER LOCATED IN BLOWER COMPARTMENT

FURNACE		FILTER SIZE (IN)
CASING				FILTER
	Side Return†
WIDTH (IN.)			Bottom Return	TYPE
17-1/2	(1)	16 x 25 x 1*	(1) 16 x 25 x 1*	Cleanable
21	(1)	16 x 25 x 1	(1) 20 x 25 x 1*	Cleanable
24-1/2	(1 or 2) 16 x 25 x 1		(1) 24 x 25 x 1*	Cleanable

AIR FILTER LOCATED IN FILTER CABINET

FILTER
CABINET	FILTER	FILTER
HEIGHT (IN)	SIZE (IN)	TYPE
16	(1) 16 x 25 x 1*	Cleanable or
	or (1) 16 x 25 x 4-5/16	Disposable

1.Turn off the gas and electrical supplies to the furnace and remove the main furnace door. (See Fig. 9, 10, and 11.)

2.Remove burner enclosure front. (See Fig. 37 or 38.)

Inspect the gas burners, igniter area, and remainder of furnace for dirt, rust, soot, or scale.

!CAUTION

If dirt, rust, soot, or scale accumulations are found, call your dealer. Do not operate your furnace. Failure to follow this caution would result in minor property or product damage.

3.Inspect the combustion-air and vent PVC pipes for sags, holes, cracks, or disconnections. Horizontal portions of pipes must slope downward toward furnace.

20	(1) 20 x 25 x 1*	Cleanable or
	or (1) 20 x 25 x 4-5/16	Disposable
24	(1) 24 x 25 x 1*	Cleanable or
	or (1) 24 x 25 x 4-5/16	Disposable

*Factory-provided with the furnace. Filters may be field modified by cutting- filter material and support rods (3) in filters. Alternate sizes and additional filters may be ordered from your dealer.

†Upflow only.

!CAUTION

Upflow

Downflow

3738

Use care when cutting support rods in filters to protect against flying pieces and sharp rod ends. Wear safety glasses, gloves, and appropriate pro- tective clothing. Failure to follow this caution could result in personal injury.

COMBUSTION AREA AND VENT SYSTEM

!DANGER

If holes are found in the pipes or if any portion has become disconnected, toxic fumes can escape into your home. DO NOT OPERATE YOUR FURNACE. Call your dealer for service. Failure to follow this warning could result in personal injury or death.

Visually inspect the combustion area and vent system before each heating season. Make sure that all PVC pipes leading into the combustion area and vent are free from any cracks and sags. Check the combustion-air intake and vent pipe on the outside of your home for blockage.

4.Reinstall burner enclosure front.

5.If your furnace is free of the above conditions, replace main furnace door and turn on electrical and gas supplies to the furnace. (See Fig. 16, 17, and 18.)

6.Start the furnace and observe its operation. Watch the burner flames to see if they are clear blue, almost transpar- ent. (See Fig. 36.) If you observe a suspected malfunction, or the burner flames are not clear blue, call your dealer.

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