Please help ASAP on Atwood Furnace

BURNER FAILS TO IGNITE AND BLOWER FAILS TO RUN

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CONDITION
SOLUTION


1)No electrical power to the furnace
2)Thermostat defective
3)Thermostat wires broken or shorted
4)Current overload protector device defective or
tripped (circuit breaker)
5)Blower relay defective
6)Wire off motor
7)Wire off relay
8)Improper ground
9)Blower motor defective

1a)Reconnect or replace power source*
2a)Replace thermostat
3a)Replace wire or wires*
4a)Reset circuit breaker
Check amp draw from motor according to furnace's specification
5A)Replace relay
6a)Reconnect wire
7a)Reconnect wire
8a)Clean and secure grounds*
9a)Replace motor



BLOWER RUNS BUT FAILS TO IGNITE

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CONDITION
SOLUTION


1)Low voltage
2)Gas pressure incorrect

3)Furnace grounding wires not secure
4)Air intake restricted
5)12 volt polarity reversed
6)Motor running slow

7)Exhaust blocked
8)Combustion air wheel loose
9)Sail switch defective or wire off
10)Limit switch defective or off wire
11)Edge connector on cicuit board dirty
12)Circuit board defective
13)
Gas valve defective

14)Main burner orifice blocked
15)High tension lead wire defective
16)Electrode out of adjustment
17)Electrode defective
18)Obstructed burner head

1a)Correct Power Supply*
2a)Set pressure to a minimum of 11"W.C. with all appliances running. (Replace regulator if not obtainable).*
3a)Clean and secure grounds established*
4a)Clean air intake*
5a)Correct polarity*
6a)Check voltage first
If 12 VDC while running, replace motor
7a)Clean exhaust*
8a)Reposition and tighten
9aReconnect wire or replace
10aReconnect wire or replace
11a)Clean with pencil eraser
12a)Clean plug contacts. If still defective, replace. (check on board tester when possible).
13a)Replace valve or valve coil, depending on problem encountered
14a)Clean main burner orifice or replace
15a)Replace wire
16a)Adjust electrode (take care not to damage porcelain)
17a)Replace
18a)Clean burner head*



BURNER IGNITES BUT IGNITION SYSTEM "LOCKS OUT" AND TURNS BURNER OFF

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CONDITION
SOLUTION


Low gas pressure

Exhuast blocked
Combustion air wheel loose
Electrodes out of adjustment
Electrode defective
Circuit board defective

Flame sensor wire between electrode and
circuit board defective
Air leakage at gaskets
Defective heat exchanger

Set pressure to a minimum of 11"W.C. with all appliances running. Replace regulator if not obtainable.*
Clean Exhaust*
Reposition wheel and tighten
Adjust electrode according to furnace specifications
Replace electrode
Clean plug contacts. If still defective, replace. (Check on board tester when possible).
Replace wire

Replace gasket
Replace heat exchanger



SOOTING (caused by lazy yellow flame)

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CONDITION
SOLUTION


Low gas pressure

Low voltage
Air leakage at gaskets
Combustion wheel installed backwards
Blockage in heating chamber or burner head
Faulty motor

*Set pressure to a minimum of 11"W.C. with all appliances running. Replace regulator if not obtainable
Correct power supply*
Replace gaskets
Reposition wheel and tighten
Clean or replace
Replace motor



FAN RUNS CONTINOUSLY WITH THERMOSTAT "OFF"

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CONDITION
SOLUTION


Defective thermostat
Shorted thermostat leads
Defective relay

Replace thermostat
*Replace wire or wires.
Replace relay



LIMITING = BURNER CYCLING ON AND OFF
BLOWER RUNS CONSTANTLY WITH THERMOSTAT ON

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CONDITION
SOLUTION


Furnace over fired

Restricted return air supply

Restricted or insufficient discharge ducting

Defective limit switch

Set gas pressure to a minimum of 11"W.C. with all appliances running. Replace regulator if not obtainable. Also, check main burner orifice, it must comply with furnace's specifications.*
Make sure return air meets furnace's minimum requirements.*

a. Ducting must meet furnace's minimum requirements*
b. No excess ducting or unnecessary bends*
c. All closeable registers must be fully open and unrestricted*
Replace limit switch



BLOWER SHUTS OFF AT SAME TIME BURNER SHUTS OFF

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CONDITION
SOLUTION


Wired wrong
Faulty relay

Correct wiring*
Replace relay



BLOWER VIBRATES OR IS NOISY

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CONDITION
SOLUTION


Motor mount loose

Damaged blower wheel
Motor shaft bent

Tighten motor mounting bracket
a. Ducting must meet furnace's minimum requirements* b. No excess ducting or unecessary bends* c. All closable registers must be fully open and unrestricted
Replace blower wheel
Replace blower motor



INSUFFICIENT HEAT

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CONDITION
SOLUTION


Furnace under fired

1. Set gas pressure to 11"W.C. with all appliances running. Replace regulator if not obtainable. Also, check main burner orifice, it must comply with furnace's specifications*
2. Check ducting and return air according to furnaces specifications*