Furnace - Electronic Ignition Models (Continued) - Atwood AFS Series Training Manual

Restricted or insufficient discharge ducting
Furnace over fired
Restricted return air supply
Defective limit switch
Furnace – Electronic Ignition Models (continued)
* NOT COVERED UNDER WARRANTY
CAUSE
BLOWER SHUTS OFF AT SAME TIME BURNER SHUTS OFF
Wired wrong
Faulty relay
BLOWER VIBRATES OR IS NOISY
Motor mount loose
Damaged blower wheel
Motor shaft damaged
INSUFFICIENT HEAT
Furnace under fired
Furnace improperly sized for coach/or conditions
BURNER FAILS TO IGNITE AND - BLOWER FAILS TO RUN
No electrical power to the furnace
Current overload protector device
Thermostat defective
Thermostat wires broken
Blower motor defective
Blower relay defective
Wire off motor
Wire off relay
Improper ground
BLOWER RUNS – BUT FAILS TO IGNITE (PILOT)
Low Voltage/High Voltage
12 volt polarity reversed
Furnace grounding wires not secure
Gas valve defective
Gas pressure incorrect
Limit switch defective or wire off
Sail switch defective or wire off
Burner orifice blocked
Combustion air wheel loose
Burner head adjustment
Exhaust blocked
Air intake restricted
Broken or loose wire
Motor running slow
Pilot orifice plugged
Thermocouple defective
Pilot assembly defective
BURNER CYCLING ON AND OFF – BLOWER RUNS CONTINUOUSLY WITH THERMOSTAT "ON"
Restricted return air supply
Restricted discharge duct system
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 *
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 minimum requirements *
Replace limit switch
Correct wiring *
Replace relay
Tighten motor mounting bracket
a. Ducting must meet furnace's minimum requirements *
b. No excess ducting or unnecessary bends *
c. All closeable registers must be fully open and
Replace blower wheel
Replace motor
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 *
Replace furnace with proper size
Reconnect or replace power source *
Reset circuit breaker. Check amp draw from motor defective or tripped
(circuit breaker) according to furnace's specifications
Replace thermostat
Replace wire or wires *
Replace motor
Replace relay
Reconnect wire *
Reconnect wire *
Clean and secure grounds *
Correct power supply *
Correct polarity *
Clean and secure ground established *
Replace valve or valve coil, depending on problem encountered
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 *
Reconnect wire or replace
Reconnect wire or replace
Clean main burner orifice or replace
Reposition and tighten
Reposition and tighten. Adjust burner according to furnace specifications
Clean exhaust *
Clean air intake *
Replace or tighten *
Check voltage first. If 12 VDC while running, replace motor
Clean or replace orifice *
Replace thermocouple
Replace pilot assembly
Make sure return air meets furnace's minimum requirements *
a. Ducting must meet furnace's minimum requirements *
b. No excess ducting or unnecessary bends *
44
SOLUTION
unrestricted*