Carrier 58DFA instruction manual Yes

Replace

board.

Turn on 115-VAC

power to unit.

Is blower running?

NO

Jumper across screws R & G.

Is

blower running

on cooling

speed?

YES

Is

NO115VAC across EAC-1

& COM?

	START
	Disconnect all thermostat
	wires from board.
YES	Is 24VAC	YES
	across screws

R & C?

NO

Check/Replace:

1.Limit switch

2.Limit shield (if used)

3.Fuse link

4.Auxillary limit switch (if used)

5.Wire harness

Is

NO115VACNO across HI &

COM?

YES

Replace

blower motor

and/or start

capacitor.

Is 24VAC		YES
across screws
W & C or
G & C?
	NO

Is

115VACYES across L1 &

L2?

NO

Check/Replace:

1.Unit power

2.Door switch

3.Power harness

Turn off 115-VAC

power to unit.

NO

Are

all thermostat wires to board disconnected?

YES

Replace

board.

YES

Is

24VAC

across screws

R & C?

NO

Check/Replace:

1.3-amp board fuse

2.Transformer

YES

Remove

R & G jumper.

Check pressure tube for leak or crimp; otherwise, replace pressure switch

YES

Is

24VAC

across PL1-2 & screw C on board?

NO

NO	Replace
	board.

NODoes blower turn

off?

YES

Is heat

exchangerYES pressure drop greater

than 0.35-in.

wc?

NO

YES

Is 24VAC

across pressure

switch N/O contact

&screw C on board?

NO

Repair wire

harness.

Jumper across screws R & W.

Is

inducer motor

on?

NO

Check/Replace:

1.Vent systems

2.Induce wheel

3.Flue choke

4.Inducer voltage

5.Inducer motor bearings

YES	Is	NO
	unit lit?

YES

Is 24VAC

across pressure

switch N/O contact

&screw C on board?

NO

Is

24VAC across gas

valve?

YES	Check/Replace:
	1.	Draft safeguard switch
	2.	Wire harness
YES	Check/Replace:
	1.	Pilot
	2.	Thermocouple
	3.	Gas valve

Replace

YES

Is

115VAC across

Is

blower running NO on heat speed 45

Is

115VAC across

YES	Replace
	blower motor

inducer motor.

NO

Check/Repair wire harness; otherwise, replace pressure switch.

inducer motor

connector?

NO

Is

24VAC across PL-2 & screw C on board?

YES

Replace

board.

NO

sec after unit

lights?

YES

Is

115VAC

across EAC-1

& COM?

YES

Remove

R & M jumper.

inducer motor

connector?

NO

Is

24VAC across

PL-1 & screw C on board?

NO

Repair wire

harness.

		and/or start
		capacitor.
YES
		Replace
		board.
		Check/Replace
		thermostat
		and/or
	thermostat wiring.

NO

After

off-delay YES does blower

turn off?

		NO
Reconnect all	Does unit
thermostat wires.	operate?

NOTE: After replacing any component, verify correct operating sequence as indicated by bold arrows.

YES

END OF TEST.

A91253

Copyright 1993 CARRIER Corp. · 7310 W. Morris St. · Indianapolis, IN 46231 35005c

Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.

Book		1	4	PC 101	Catalog No. 565-801	Printed in U.S.A.	Form 58D,G-3SM	Pg 8	11-93	Replaces: 58D,G-2SM
	Tab	6a	8a