Atwood AFS Series - User Manual

Questions and Answers

S
slandryAug 18, 2025
What to do if Atwood AFS burner fails to ignite and blower fails to run?
- S
  Shannon MiddletonAug 18, 2025
  If the Atwood furnace burner fails to ignite and the blower doesn't run, start by checking the electrical power to the furnace, reconnecting or replacing the power source if necessary. If the power source is ok, replace the thermostat if it’s defective. Also, replace any broken or shorted thermostat wires. Reset the circuit breaker if a current overload protector device has tripped, and check the amp draw from the motor. Finally, inspect the circuit breaker for defects or tripping, referring to the furnace specifications.
M
Mr. Lonnie BuckAug 21, 2025
Why Atwood AFS blower does not run?
- J
  Jose GordonAug 21, 2025
  If the Atwood furnace blower does not run, check the following: * Ensure the temperature selector is correctly set. * Repair or replace any broken or disconnected thermostat wires. * If the heat anticipator is burned out due to a short, repair the short and replace the thermostat. * Replace the relay and thermostat if the faulty relay draws more than 1 amp. * Replace the thermostat if there is no continuity through it with contacts closed and the switch on. * If there is continuity through the thermostat with contacts closed and the switch on, check and reestablish power to the thermostat, reset any tripped circuit breakers, correct poor grounding, correct any loose wires, and replace any defective relays or motors.
T
Timothy JonesAug 25, 2025
How to fix soot caused by lazy yellow flame in Atwood Furnace?
- W
  Warren BryanAug 26, 2025
  Soot, indicated by a lazy yellow flame in your Atwood furnace, can stem from several issues. Begin by ensuring the gas pressure is at least 11” W.C. with all appliances running, replacing the regulator if necessary. Also, verify that the power supply provides correct voltage. Replace any gaskets with air leaks. Check the combustion wheel installation (it shouldn't be installed backwards or loose), reposition and tighten it if necessary. Inspect for any blockages in the heating chamber or burner head, cleaning or replacing parts as needed. If the motor is faulty, replace it. Finally, ensure the vent kit or draft cap is correct for your unit, replacing it if it is not.
W
wilsondestinyAug 27, 2025
Why Atwood AFS does not cycle properly?
- M
  Michele JacksonAug 27, 2025
  If the Atwood furnace isn't cycling properly, consider these points. If it cycles too quickly, move the anticipator to a higher amp setting to lengthen the cycle, also ensure the thermostat isn't too close to a heat duct; if it is, relocate either the thermostat or the duct outlet. For high temperature variance, move the anticipator to a lower setting to shorten the cycle.
Q
qwilsonAug 31, 2025
Why Atwood AFS Furnace fan runs continuously with thermostat off?
- M
  Miguel MillsAug 31, 2025
  If the Atwood furnace fan runs continuously even with the thermostat set to “off”, there are a few potential causes. The thermostat itself may be defective and need replacement. Alternatively, there could be shorted thermostat leads, which would require replacing the wire or wires. Lastly, a defective relay could be the culprit, necessitating its replacement.
H
Heidi GomezSep 3, 2025
What to do if Atwood AFS burner ignites then locks out?
- P
  Phillip BairdSep 3, 2025
  If the Atwood furnace burner ignites but the ignition system locks out and turns the burner off, consider the following: * Ensure gas pressure is at a minimum of 11” W.C. with all appliances running, replacing the regulator if needed. * Check for and clear any exhaust blockages. * Reposition and tighten the combustion air wheel if it is loose. * Adjust the electrodes according to furnace specifications, or replace them if defective. * Clean the plug contacts on the circuit board, and replace the board if it remains defective. * Replace the flame sensor wire if it is defective. * Replace any gaskets with air leaks. * Consider replacing the heat exchanger if it is defective.
M
Mary LoweSep 7, 2025
Why Atwood Furnace has insufficient heat?
- A
  alex26Sep 7, 2025
  If your Atwood furnace isn't producing enough heat, first ensure it's not underfired. Set the gas pressure to 11” W.C. with all appliances running, and replace the regulator if this pressure isn't obtainable. Also, check the main burner orifice to ensure it meets the furnace's specifications. Secondly, inspect the ducting and return air setup, ensuring they meet the furnace's specifications. If the furnace is improperly sized for the coach or conditions, replace it with one of the proper size.
S
Steven ScottSep 10, 2025
Why Atwood AFS Furnace blower vibrates or is noisy?
- H
  Heather FitzgeraldSep 10, 2025
  If the Atwood furnace blower vibrates or is noisy, check if the motor mount is loose and tighten the mounting bracket. Ensure the ducting meets the furnace’s minimum requirements, without excess ducting or unnecessary bends. All closeable registers must be fully open and unrestricted. If the blower wheel is damaged, replace it. If the motor shaft is damaged, replace the motor.
N
Nicholas WilliamsNov 13, 2025
What to do if the blower runs but the Atwood AFS fails to ignite?
- M
  michellemartinezNov 14, 2025
  If the blower runs but the Atwood furnace fails to ignite, several factors could be at play. First, ensure the power supply is correct. Second, verify that the gas pressure is at least 11” W.C. with all appliances running; if not, replace the regulator. Check that the furnace grounding wires are secure and the air intake is not restricted. Other potential issues include a slow-running motor (check voltage, replace if necessary), reversed 12-volt polarity, a blocked exhaust, a loose combustion air wheel, or a defective/disconnected sail or limit switch. Also, inspect for dirty edge connectors or circuit boards, a defective circuit board or gas valve, a blocked main burner orifice, a defective high tension lead wire or electrode (misadjusted or defective), or an obstructed burner head. Addre...

Summary

Introduction

Recommended Tools and Equipment

U-Tube Manometer

Description and illustration of the U-tube manometer for gas pressure measurement.

Multi-meter

Description of the multi-meter for electrical testing of voltage, amperage, and continuity.

Circuit Board Tester

Details on a table-top device for testing furnace circuit board functions.

AFS Series Model Identification

AFS Series Applications

Typical installation environments for AFS series furnaces.

AFS Series Serviceability

Information on furnace accessibility for repairs and service.

AFS Series Required Ducting

Specifications and recommendations for AFS furnace ducting.

AFS Wiring Diagram

AFM Series Model Identification

AFM Series Applications

Typical installation environments for AFM series furnaces.

AFM Series Serviceability

Information on furnace accessibility for repairs and service.

AFM Series Required Ducting

Specifications and recommendations for AFM furnace ducting.

AFM Wiring Diagram

AFL Series Model Identification

AFL Series Applications

Typical installation environments for AFL series furnaces.

AFL Series Serviceability

Information on furnace accessibility for repairs and service.

AFL Series Required Ducting

Specifications and recommendations for AFL furnace ducting.

AFL Wiring Diagram

79;80 Series Model Identification

79;80 Series Applications

Typical installation environments for 79/80 series furnaces.

79;80 Series Serviceability

Information on furnace accessibility for repairs and service.

79;80 Series Minimum Ducting Configuration

Guidelines for optimal airflow and heat distribution with ducting.

7900 & 8012 Wiring Diagrams

79;80-1 Single Sense Blower Relay Wiring

Wiring diagram for single sense blower relay configuration.

79;80-1 Dual Sense Blower Relay Wiring

Wiring diagram for dual sense blower relay configuration.

8500 Series Model Identification

8500 Series Applications

Typical installation environments for 8500 series furnaces.

8500 Series Serviceability

Information on furnace accessibility for repairs and service.

8500 Series Wiring Diagrams

Wiring diagrams for 8500 series models.

85-II Remote Sense Wiring

85-III Local Sense Wiring

85-III AC Wiring Local Sense

85-IV Blower Control Wiring with Field Plug

85-IV Blower Control Wiring (No Field Plug)

8900 Series Model Identification

8900 Series Applications

Typical installation environments for 8900 series furnaces.

8900 Series Serviceability

Information on furnace accessibility for repairs and service.

8900 Series Wiring Diagrams

Wiring diagrams for 8900 series models.

89-II DC Wiring Local Sense

89-III AC Wiring Local Sense

85;89 Series Two Stage Model Identification

85;89 Series Two Stage Applications

Typical installation environments for 85/89 series two-stage furnaces.

85;89 Series Two Stage Serviceability

Information on furnace accessibility for repairs and service.

2-Stage Wiring Diagrams

2-Stage Wiring with Field Plug

Wiring diagram for 2-stage models with a field plug.

2-Stage Wiring without Field Plug

Wiring diagram for 2-stage models without a field plug.

HFH 2000 Bi Metal Thermostat

HFH 2000 Thermostat Specifications

Technical specifications for the HFH 2000 thermostat model 1H1C.

HFH 2000 Thermostat Location

Recommended placement guidelines for thermostat installation.

Removing Old Thermostat

Installing New Thermostat

Digital Thermostat Model 1 H2 C

1 H2 C Digital Thermostat Specifications

Technical specifications for the 1H2C digital thermostat.

1 H2 C Digital Thermostat Installation

Guidelines for installing the 1H2C digital thermostat.

Atwood Thermostat Wiring Requirements

Digital Thermostat Model 2 H2 C Two Stage

2 H2 C Two Stage Thermostat Specifications

Technical specifications for the 2H2C two-stage digital thermostat.

Atwood Two Stage Thermostat Wiring Requirements

Wiring requirements for Atwood two-stage thermostats.

Sequence of Operation: DC Standard Models

Sequence of Operation: DC 2-Stage Excalibur Models

Sequence of Operation: Pilot Models

Sequence of Operation: AC Models

Critical Installation Criteria

Annual Preventative Maintenance Inspection

Recommended safety checks and maintenance procedures for furnaces.

Thermostat Location Guidelines

Circuit Breaker and Motor

Circuit Boards

Relay Function and Operation

Sail Switch Function

Limit Switch Function

Dual Solenoid Gas Valve

Burner Head, Electrode, and Valve Assembly

Minimum Ducting Requirements

Trouble Shooting Guides

Troubleshooting: Mechanical Thermostat

Troubleshooting steps for mechanical thermostat issues like blower not running.

Troubleshooting: Furnace Cycling Issues

Diagnosing and resolving issues with furnace cycling properly.

Troubleshooting: Burner Fails to Ignite; Blower Fails to Run

Troubleshooting steps when burner fails to ignite and blower does not run.

Troubleshooting: Ignition and Control Failures

Diagnosing ignition lockout, fan run, and electronic control issues.

Troubleshooting: Insufficient Heat and Operational Issues

Troubleshooting: Pilot and Flame Issues

Furnace Terminology

Flat Rate Schedule

AFS Series Service Parts

AFL Series Service Parts

7900-II; 8012-II Series Furnace Parts

7900-8012 Series Service Parts

8500-IV LD & 2-Stage Series Furnace Parts

8500 Series Service Parts

8900-IV DC & AC Series Furnace Parts

8900 Service Parts

Furnace Limited Warranty

Furnace Extended Service Contract

Information on purchasing and terms of an extended service contract.

Warranty Exclusions

Specific items and conditions excluded from the furnace warranty coverage.

Warranty Limitations

Limitations on Atwood's liability under the furnace warranty.

Summary

Introduction

Recommended Tools and Equipment

U-Tube Manometer

Description and illustration of the U-tube manometer for gas pressure measurement.

Multi-meter

Description of the multi-meter for electrical testing of voltage, amperage, and continuity.

Circuit Board Tester

Details on a table-top device for testing furnace circuit board functions.

AFS Series Model Identification

AFS Series Applications

Typical installation environments for AFS series furnaces.

AFS Series Serviceability

Information on furnace accessibility for repairs and service.

AFS Series Required Ducting

Specifications and recommendations for AFS furnace ducting.

AFS Wiring Diagram

AFM Series Model Identification

AFM Series Applications

Typical installation environments for AFM series furnaces.

AFM Series Serviceability

Information on furnace accessibility for repairs and service.

AFM Series Required Ducting

Specifications and recommendations for AFM furnace ducting.

AFM Wiring Diagram

AFL Series Model Identification

AFL Series Applications

Typical installation environments for AFL series furnaces.

AFL Series Serviceability

Information on furnace accessibility for repairs and service.

AFL Series Required Ducting

Specifications and recommendations for AFL furnace ducting.

AFL Wiring Diagram

79;80 Series Model Identification

79;80 Series Applications

Typical installation environments for 79/80 series furnaces.

79;80 Series Serviceability

Information on furnace accessibility for repairs and service.

79;80 Series Minimum Ducting Configuration

Guidelines for optimal airflow and heat distribution with ducting.

7900 & 8012 Wiring Diagrams

79;80-1 Single Sense Blower Relay Wiring

Wiring diagram for single sense blower relay configuration.

79;80-1 Dual Sense Blower Relay Wiring

Wiring diagram for dual sense blower relay configuration.

8500 Series Model Identification

8500 Series Applications

Typical installation environments for 8500 series furnaces.

8500 Series Serviceability

Information on furnace accessibility for repairs and service.

8500 Series Wiring Diagrams

Wiring diagrams for 8500 series models.

85-II Remote Sense Wiring

85-III Local Sense Wiring

85-III AC Wiring Local Sense

85-IV Blower Control Wiring with Field Plug

85-IV Blower Control Wiring (No Field Plug)

8900 Series Model Identification

8900 Series Applications

Typical installation environments for 8900 series furnaces.

8900 Series Serviceability

Information on furnace accessibility for repairs and service.

8900 Series Wiring Diagrams

Wiring diagrams for 8900 series models.

89-II DC Wiring Local Sense

89-III AC Wiring Local Sense

85;89 Series Two Stage Model Identification

85;89 Series Two Stage Applications

Typical installation environments for 85/89 series two-stage furnaces.

85;89 Series Two Stage Serviceability

Information on furnace accessibility for repairs and service.

2-Stage Wiring Diagrams

2-Stage Wiring with Field Plug

Wiring diagram for 2-stage models with a field plug.

2-Stage Wiring without Field Plug

Wiring diagram for 2-stage models without a field plug.

HFH 2000 Bi Metal Thermostat

HFH 2000 Thermostat Specifications

Technical specifications for the HFH 2000 thermostat model 1H1C.

HFH 2000 Thermostat Location

Recommended placement guidelines for thermostat installation.

Removing Old Thermostat

Installing New Thermostat

Digital Thermostat Model 1 H2 C

1 H2 C Digital Thermostat Specifications

Technical specifications for the 1H2C digital thermostat.

1 H2 C Digital Thermostat Installation

Guidelines for installing the 1H2C digital thermostat.

Atwood Thermostat Wiring Requirements

Digital Thermostat Model 2 H2 C Two Stage

2 H2 C Two Stage Thermostat Specifications

Technical specifications for the 2H2C two-stage digital thermostat.

Atwood Two Stage Thermostat Wiring Requirements

Wiring requirements for Atwood two-stage thermostats.

Sequence of Operation: DC Standard Models

Sequence of Operation: DC 2-Stage Excalibur Models

Sequence of Operation: Pilot Models

Sequence of Operation: AC Models

Critical Installation Criteria

Annual Preventative Maintenance Inspection

Recommended safety checks and maintenance procedures for furnaces.

Thermostat Location Guidelines

Circuit Breaker and Motor

Circuit Boards

Relay Function and Operation

Sail Switch Function

Limit Switch Function

Dual Solenoid Gas Valve

Burner Head, Electrode, and Valve Assembly

Minimum Ducting Requirements

Trouble Shooting Guides

Troubleshooting: Mechanical Thermostat

Troubleshooting steps for mechanical thermostat issues like blower not running.

Troubleshooting: Furnace Cycling Issues

Diagnosing and resolving issues with furnace cycling properly.

Troubleshooting: Burner Fails to Ignite; Blower Fails to Run

Troubleshooting steps when burner fails to ignite and blower does not run.

Troubleshooting: Ignition and Control Failures

Diagnosing ignition lockout, fan run, and electronic control issues.

Troubleshooting: Insufficient Heat and Operational Issues

Troubleshooting: Pilot and Flame Issues

Furnace Terminology

Flat Rate Schedule

AFS Series Service Parts

AFL Series Service Parts

7900-II; 8012-II Series Furnace Parts

7900-8012 Series Service Parts

8500-IV LD & 2-Stage Series Furnace Parts

8500 Series Service Parts

8900-IV DC & AC Series Furnace Parts

8900 Service Parts

Furnace Limited Warranty

Furnace Extended Service Contract

Information on purchasing and terms of an extended service contract.

Warranty Exclusions

Specific items and conditions excluded from the furnace warranty coverage.

Warranty Limitations

Limitations on Atwood's liability under the furnace warranty.

Atwood AFS Series Specifications

General

Brand	Atwood
Model	AFS Series
Category	Furnace
Language	English

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Atwood AFS Series - User Manual

Table of Contents

Questions and Answers

Summary

Introduction

Recommended Tools and Equipment

U-Tube Manometer

Multi-meter

Circuit Board Tester

AFS Series Model Identification

AFS Series Applications

AFS Series Serviceability

AFS Series Required Ducting

AFS Wiring Diagram

AFM Series Model Identification

AFM Series Applications

AFM Series Serviceability

AFM Series Required Ducting

AFM Wiring Diagram

AFL Series Model Identification

AFL Series Applications

AFL Series Serviceability

AFL Series Required Ducting

AFL Wiring Diagram

79;80 Series Model Identification

79;80 Series Applications

79;80 Series Serviceability

79;80 Series Minimum Ducting Configuration

7900 & 8012 Wiring Diagrams

79;80-1 Single Sense Blower Relay Wiring

79;80-1 Dual Sense Blower Relay Wiring

8500 Series Model Identification

8500 Series Applications

8500 Series Serviceability

8500 Series Wiring Diagrams

85-II Remote Sense Wiring

85-III Local Sense Wiring

85-III AC Wiring Local Sense

85-IV Blower Control Wiring with Field Plug

85-IV Blower Control Wiring (No Field Plug)

8900 Series Model Identification

8900 Series Applications

8900 Series Serviceability

8900 Series Wiring Diagrams

89-II DC Wiring Local Sense

89-III AC Wiring Local Sense

85;89 Series Two Stage Model Identification

85;89 Series Two Stage Applications

85;89 Series Two Stage Serviceability

2-Stage Wiring Diagrams

2-Stage Wiring with Field Plug

2-Stage Wiring without Field Plug

HFH 2000 Bi Metal Thermostat

HFH 2000 Thermostat Specifications

HFH 2000 Thermostat Location

Removing Old Thermostat

Installing New Thermostat

Digital Thermostat Model 1 H2 C

1 H2 C Digital Thermostat Specifications

1 H2 C Digital Thermostat Installation

Atwood Thermostat Wiring Requirements

Digital Thermostat Model 2 H2 C Two Stage

2 H2 C Two Stage Thermostat Specifications

Atwood Two Stage Thermostat Wiring Requirements

Sequence of Operation: DC Standard Models

Sequence of Operation: DC 2-Stage Excalibur Models

Sequence of Operation: Pilot Models

Sequence of Operation: AC Models

Critical Installation Criteria

Annual Preventative Maintenance Inspection

Thermostat Location Guidelines

Circuit Breaker and Motor

Circuit Boards

Relay Function and Operation

Sail Switch Function

Limit Switch Function

Dual Solenoid Gas Valve

Burner Head, Electrode, and Valve Assembly

Minimum Ducting Requirements

Trouble Shooting Guides