Dometic DF Series Service Manual
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Dometic DF Series Service Manual

Heating furnaces
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HEATING
FURNACES
AFS/DFS, AFM/DFM, AFL/DFL, 79/80, 85/89
DF Series Furnaces
EN
Service Manual
Form No. 31315 07/18 | ©2018 Dometic Corporation

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  • Page 1 HEATING FURNACES AFS/DFS, AFM/DFM, AFL/DFL, 79/80, 85/89 DF Series Furnaces Service Manual Form No. 31315 07/18 | ©2018 Dometic Corporation...

  • Page 2: Table Of Contents

    Furnaces NORTH AMERICAN ADDRESS INFORMATION U.S.A. & CANADA Service Center & Dealer Locations Service Office Visit: www.dometic.com Dometic Corporation 1120 North Main Street Elkhart, IN 46514 CONTENTS Explanation of symbols and safety instructions ..........2 Intended use .

  • Page 3: Intended Use

    • HAZARDOUS WASTE HAZARD. Some old thermostats may contain mercury. Handle with care. Dispose of properly. • ELECTRICAL SHOCK, FIRE, EXPLOSION, AND/OR CARBON MONOXIDE HAZARD. – Use only Dometic replacement parts and components, which are specifically approved for use with the Furnace. – Disconnect electricity to the appliance before installation or service.

  • Page 4: Operational Issues And Diagnostics

    Furnaces 3 OPERATIONAL ISSUES AND DIAGNOSTICS This section has tables showing the main causes for furnace issues. The Operational Issues table helps you identify a range of furnace operational issues and the potential servicing solutions associated with those issues. The Diagnostics table links specific furnace components to the diagnostic tasks associated with that component. Remember to check the basics before replacing any parts, such as loose wiring and overall heating issues.
  • Page 5 Furnaces Potential Reason Operational Issue Page Thermostat is calling for heat – no Air conditioner board issue fan/no operation DC voltage issue Defective circuit board Defective motor Defective external relay Defective sail switch Fan runs continuously with Defective circuit board/fan relay on board is stuck closed thermostat set to off Defective external relay Visible buildup of soot...

  • Page 6: General Information

    Furnaces 4 GENERAL INFORMATION This section provides reference information on the tooling, model identification, components, operation, and terminology associated with the different furnace models. 4.1 Tools and materials Required Tools U-tube manometer with 1/8" pipe nipple Incline manometer Multimeter Circuit board tester Air-speed indicator Long-handled Allen wrenches (9/64"...
  • Page 7 Furnaces AF/DF Series DF M D 30 1 1 1 Rate Stages Door Style Type of Gas Model number example: DFMD30111 BTU/hr Rating Voltage Cabinet Size Furnace Type Furnace Cabinet Type of Rate Voltage BTU Rating Door Style Type Size...
  • Page 8 Furnaces 4.3 Component locations AF/DF Series Possible On/Off Switch/ Circuit Breaker Location (LD Models) Blower Wheel Heat Exchanger Possible Sail Switch Location Limit Switch Possible On/Off Switch/ Circuit Breaker Location Circuit Board Gas Valve Possible Sail Switch Location Combustion Wheel...
  • Page 9 Furnaces 4.4 Sequence of operation/wiring diagrams The wiring diagrams shown are the best representations of each furnace. Wire colors may vary. Understanding the sequence of operations for a furnace is an important part of diagnosing the operational issues occurring in the furnace. This section details the wiring and sequence of operation for each furnace type: •...
  • Page 10 Furnaces Thermostat +12 VDC On/Off Switch (some furnaces have combination On/Off switch circuit breakers) Circuit Breaker Motor Sail (Limit and Sail Switch are Switch reversed in 79/80 series) Limit Switch Valve Ignition Control Relay This diagram shows the external relay used in furnaces built prior to 07/2001. Sequence of operation for DC models (standard units): 1.
  • Page 11 Furnaces – If the system does not ignite and the thermostat remains closed on units with an external relay, the blower will remain on until the thermostat is reset manually. Units with the relay on the ignition control will shut the blower off even if the thermostat contacts remain closed. If the thermostat is not reset within one hour, the system will try the ignition cycle again.
  • Page 12 Furnaces AC Models Limit Switch Sail Switch Blue Blue Ignition Valve Control ON/OFF Green Switch Green Green White Transformer Yellow Blue Blue White Electrode Yellow Green Black Blue Black White Green White Black Brown Motor Capacitor 24 VAC (Older Models) Circuit Breaker or Breaker/Switch Combination...
  • Page 13 Furnaces Sequence of operation for AC models: 1. The transformer receives 120 VAC, which it converts to 24 VAC for the operating circuitry. 2. The thermostat controls the operating circuit to the furnace by reacting to room temperature. When room temperature is below the thermostat set-point, the contacts close to allow current to flow to the relay (the relay can be either external or part of the ignition control board).
  • Page 14 Furnaces Two-Stage Models (1522, 2334, and 2540) Ground Black Thermostat (Ground) Electrode Motor High Ignition Voltage Control Dual- 5ON-12 Control Circuit Power Breaker 5 4 3 2 1 Switch 1 2 3 4 5 6 Orange White Power to DSI Board Ground Sail Limit...
  • Page 15 Furnaces 6. Circulating air blows against the sail switch and closes the contacts, completing the circuit. The sail switch is a safety device that ensures airflow before ignition. 7. The limit switch is a safety device that protects the furnace from overheating. The contacts in the limit switch open at a given temperature setting, shutting off power.
  • Page 16 Furnaces 4.5 General furnace terminology Term Definition Term Definition AC Motor A motor operating on 120 VAC A conductor that establishes an electrical spark at the burner Adjustable A heat outlet capable of being Electrode to ignite the air-to-gas mixture. Register opened and closed Senses and signals the circuit...
  • Page 17 Furnaces Term Definition Term Definition Air pulled into the furnace, heated, Incline Tool used to measure static Manometer pressure of the furnace plenum Return Air and forced through duct outlets into the living area An enclosure inside the furnace Junction Box Caused when the circuit board that houses wire connections Safety Lockout...

  • Page 18: Diagnostic Procedures

    5 DIAGNOSTIC PROCEDURES  ELECTRICAL SHOCK, FIRE, EXPLOSION, AND/OR CARBON MONOXIDE HAZARD. Use only Dometic replacement parts and components, which are specifically approved for use with the Furnace. Failure to obey this warning could result in death or serious injury.
  • Page 19 Furnaces Component Diagnostic Question Action Based On Status Page Burner Head Inspect the burner head. Is Yes = Replace the burner head there visible damage (rust, burnt • Determine the cause of the rust through)? and repair • Check for improper combustion, low gas pressure, or blockage.
  • Page 20 Furnaces Component Diagnostic Question Action Based On Status Page Is there power at the thermostat No = terminal on the board? • Confirm the thermostat is calling for heat • Confirm there is power at the thermostat and at the air conditioner control box Is there power going out to the fan No = Check the sail switch...
  • Page 21 Furnaces Component Diagnostic Question Action Based On Status Page Is the board getting wet on the Yes = AFM series furnace? • Check the door installation. Replace the door if: – The flange is installed upside down – Screws are missing –...
  • Page 22 Furnaces Component Diagnostic Question Action Based On Status Page Combustion Wheel Inspect the combustion wheel. Is Yes = Tighten or replace the there visible damage? combustion wheel Is the combustion wheel turning? No = Run tests on the motor Does the burner ignite when the No = Troubleshoot the operational blower is running? issue:...
  • Page 23 Furnaces Component Diagnostic Question Action Based On Status Page Motor Is there power going to the motor? No = • Check the sail switch • Check the circuit board operation Yes = Verify that there is a minimum of 10.5 VDC going to the motor, using a separate power source (you can have voltage without amperage).
  • Page 24 Furnaces Component Diagnostic Question Action Based On Status Page Sail Switch Inspect the sail switch. Is the Yes = Replace the sail switch paddle bent or out of alignment? Is there visible damage? • Is there continuity in the No = Replace the sail switch switch when the paddle is depressed? •...
  • Page 25 Furnaces Component Diagnostic Question Action Based On Status Page Solenoid/Gas Valve Inspect the valve. Is there visible Yes = Replace the solenoid/gas damage? valve Is excessive soot present in the Yes = combustion chamber? • Check the gas pressure • Check the burner alignment •...

  • Page 26: Heating Issues

    Furnaces 6 HEATING ISSUES A furnace is a vital part of any heating system, but it is only one part. A majority of furnace problems are caused by issues outside the product itself. When diagnosing/troubleshooting a furnace problem, always check the following items before replacing components, as the problem may stem from one of these heating issues and not the furnace: 6.1 Identifying Heating Issues...
  • Page 27 Furnaces To raise the tank temperature and increase the BTU capacity of the tank: ➤ Place an insulated, fire-resistant blanket over the tanks. ➤ Place an illuminated 75-watt light bulb under the blanket. ➤ The temperature of the bottle should rise 10°–20° F over a brief period of time, which could double the BTU capacity of the tank from the preheating state.
  • Page 28 Furnaces Identify the Duct Locations Duct 3 Duct 1 Duct 8 Duct 9 Duct 5 Duct 3 Duct 2 Duct 4 Duct 4 Duct 5 Duct 1 Duct 8 Duct 5 Duct 6 Duct 9 Horizontal Duct 7 Discharge Vertical Horizontal Discharge Duct View...
  • Page 29 Furnaces Minimum return air passageway sizes 33 in 35 in 79, 80 Series AFS, DFS Series 80 in 65 in 89, 2540 Series 85, 1522, 2334, AFM, DFM, AFL, DFL Series For additional return air passageway requirements, consult the installation instructions for the furnace. Check the Voltage If the furnace is experiencing a source issue from the power supply of the coach, the fix is not related to the furnace and could be the result of a converter issue.

  • Page 30: Service Procedures

    7.1 Accessing the furnace components  ELECTRICAL SHOCK, FIRE, EXPLOSION, AND/OR CARBON MONOXIDE HAZARD. Use only Dometic replacement parts and components, which are specifically approved for use with the Furnace. Failure to obey this warning could result in death or serious injury.
  • Page 31 Furnaces 7.2 Servicing the blower wheel Perform the steps in Accessing the furnace components (on page 30) before proceeding with service. Replace the Blower Wheel Blower Motor Housing (Rear) Blower Blower Wheel Housing (Front) Blower Wheel Compression Ring ➤ Remove the top screws on the blower housing. ➤...
  • Page 32 Furnaces 7.4 Servicing the circuit board Perform the steps in Accessing the furnace components (on page 30) before proceeding with service. Relocate the Circuit Board Replace the Circuit Board Circuit Board Circuit Board ➤ Remove the screws holding the plastic bracket to In furnaces built prior to June 2016, the circuit the furnace wall.
  • Page 33 Furnaces 7.5 Servicing the circuit breaker switch Perform the steps in Accessing the furnace components (on page 30) before proceeding with service. Reset the Circuit Breaker Switch Replace the Circuit Breaker Switch Mounted Switch Bracket Mounted Switch Circuit Breaker Switch ➤...
  • Page 34 Furnaces 7.7 Servicing the electrode The burner head, electrode, and gas valve on the late model 79 series furnaces are individually accessible. However, to service these same components on the late model 85 and 89 series, remove the complete assembly. Perform the steps in Accessing the furnace components (on page 30) before proceeding with service.
  • Page 35 Furnaces 7.8 Servicing the limit switch Perform the steps in Accessing the furnace components (on page 30) before proceeding with service. Replace the Limit Switch Limit Switch ➤ Remove the two blue wires connecting the circuit board to the limit switch. ➤...
  • Page 36 Furnaces 7.9 Servicing the motor Perform the steps in Accessing the furnace components (on page 30) before proceeding with service. Tighten the Motor Mount Motor Clamp Motor Locator Tab Blower Wheel ➤ Follow the procedure to Replace the Blower Wheel until the motor is visible.
  • Page 37 Furnaces Replace the Motor Blower Housing (Rear) Motor Blower Housing (Front) Compression Ring Combustion Wheel Blower Wheel Blower Wheel ➤ Remove the top screws on the blower housing. ➤ Remove the compression ring holding the blower wheel to the motor. ➤...
  • Page 38 Furnaces 7.11 Servicing the sail switch Perform the steps in Accessing the furnace components (on page 30) before proceeding with service. Bypass the Sail Switch Replace the Sail Switch Jumper Wire Sail Switch Sail Switch ➤ Disconnect the two wires from the sail switch. ➤...
  • Page 39 Furnaces 7.12 Servicing the gas valve The burner head, electrode, and gas valve on the late model 79 series furnaces are individually accessible. To service these same components on the late model 85 and 89 series, remove the complete assembly. Perform the steps in Accessing the furnace components (on page 30) before proceeding with service.
  • Page 40 Furnaces Replace the Solenoid/Gas Valve Electrode Valve Burner Head Valve Assembly ➤ Remove the screws securing the burner and gas ➤ Remove the screws holding the burner and gas valve assembly to the furnace. valve together. ➤ Disconnect the gas line to the gas valve. ➤...

  • Page 41: Maintenance

    – The furnace should be inspected before use and at least annually, by a qualified service person only. • ELECTRICAL SHOCK, FIRE, EXPLOSION, AND/OR CARBON MONOXIDE HAZARD. Use only Dometic replacement parts and components, which are specifically approved for use with the Furnace.
  • Page 42 Furnaces Gas Valve Venting ➤ Clean the orifice. ➤ Inspect the vent for any debris or obstructions, and clean if necessary. The orifice must be removed before cleaning. ➤ Check the draft cap assembly for proper overlap. – Refer to Servicing the gas valve (on page The vent tube should be inserted into the for the details on reaching the orifice.

  • Page 43: Disposal

    Furnaces 9 DISPOSAL Place the packaging material in the appropriate recycling waste bins, whenever possible. Consult a local recycling center or specialist dealer for details about how to dispose of the product in accordance with all applicable national and local regulations. >>...

  • Page 44: Appendix A: Supplemental Bulletins

    10 APPENDIX A: SUPPLEMENTAL BULLETINS  ELECTRICAL SHOCK, FIRE, EXPLOSION, AND/OR CARBON MONOXIDE HAZARD. Use only Dometic replacement parts and components, which are specifically approved for use with the Furnace. Failure to obey this warning could result in death or serious injury.
  • Page 45 – Wires laying on the exhaust vent tube ➤ Re-install the vent assembly. – Melting at any point along the length of the wire ➤ If either condition exists, contact the Dometic Technical Service department to obtain authorization for removal of the furnace for replacement, prior to repairing any wires or continuing with this field repair.
  • Page 46 LITERATURE NUMBER MPD 31294 DC Ignition Wiring Kit DOMETIC CORPORATION 1120 North Main Street, Elkhart, IN 46514 PHONE: 1-866-869-3118 INTERNET: WWW.EDOMETIC.COM EMAIL: CUSTOMERSUPPORTCENTER@DOMETIC.COM • Effective 9/16 KIT INCLUDES: QTY. COMPONENTS OF KIT MODELS USED ON WIRE TIE ALL MODELS DIAGNOSTIC CODE STICKER...
  • Page 47 USED COM- FURNACE D O M E T I C WIRING REQUIREMENTS FOR THERMOSTAT PRESSOR THERMOSTAT INSTALLATION 7.5 VDC ANALOG A/C SYSTEMS (DOMETIC 12 VDC ANALOG A/C SYSTEMS (RVP ® ® Thermostat is very sensitive. HANDLE THERMOSTAT WIRE FROM FURNACE...
  • Page 48 MPD 31493 LITERATURE NUMBER DOMETIC CORPORATION Model 2H2C Two Stage Furnace 1-866-869-3118 Digital Thermostat WWW.EDOMETIC.COM EMAIL: CUSTOMERSUPPORTCENTER@DOMETIC.COM FOR TWO STAGE FURNACE ENGLISH, FRANCAIS •Installation •Operation (et Canada) Effective 9/16 THIS THERMOSTAT HAS BEEN DESIGNED TO OPERATE STANDARD AIR CONDITIONING UNITS IN CONJUNCTION WITH AN EXCALIBUR...
  • Page 49 Sample change to Rating Plate location Sample change within the Installation Manuals. on top of furnace. Models AFMD16 AFMD20 AFMD25 AFMD30 AFMD35 DOMETIC CORPORATION 1120 North Main Street, Elkhart, IN 46514 Type of Propane Propane Propane Propane Propane BTU Input...
  • Page 50 MPD 32298 LITERATURE NUMBER INSTALLATION INSTRUCTIONS DOMETIC CORPORATION FURNACE REPLACEMENT 1120 North Main Street Elkhart, IN 46514  FRONT DISCHARGE 79-AFS PHONE: 1-866-869-3118 INTERNET: WWW.EDOMETIC.COM EMAIL : Effective 8/16 CUSTOMERSUPPORTCENTER@DOMETIC.COM Installation Instructions New Furnace Door Installation instruction is for use only when replacing a 7900/8000 series furnace with an AFS series units.
  • Page 52 PHONE: 1-866-869-3118 BOTTOM DISCHARGE 89- AFL INTERNET: WWW.EDOMETIC.COM EMAIL : CUSTOMERSUPPORCENTER@DOMETIC.COM Effective 9/16 Installation Instructions Bottom Discharge In cases where a bottom discharge system is used, the new unit requires an extension kit to relocate the opening to match the 89 location.
  • Page 53 MPD 32418 LITERATURE NUMBER INSTALLATION INSTRUCTIONS DOMETIC CORPORATION FURNACE REPLACEMENT 1120 North Main Street  Elkhart, IN 46514 CASING CUTOUT 85-AFM PHONE: 1-866-869-3118 Effective 9/16 INTERNET: CUSTOMERSUPPORTCENTER@DOMETIC.COM Installation Instructions AFM Casing Bottom Discharge In cases were bottom discharge is has been used for 85 the new AFM series needs to be modified for size and location.
  • Page 54 MPD 32424 LITERATURE NUMBER INSTALLATION INSTRUCTIONS FURNACE REPLACEMENT 1120 North Main Street Elkhart, IN 46514  TRIM RING INSTALL 89-AFL PHONE: 574 2131 FAX: 574 9713     INTERNET: http://www.atwoodmobile.com 7/15 Installation Instructions- AFL Furnace with Flush Door Instructions for removing “89”...
  • Page 55 MPD 32437 LITERATURE NUMBER INSTALLATION INSTRUCTIONS DOMETIC CORPORATION 1120 North Main Street Elkhart, IN 46514  FURNACE REPLACEMENT PHONE: 1-866-869-3118 TRIM RING INSTALL 85-AFM INTERNET: WWW.EDOMETIC.COM Effective 9/16 EMAIL : CUSTOMERSUPPORTCENTER@DOMETIC.COM Installation Instructions- AFM Furnace with Flush Door Instructions for removing “85” furnace with recessed door and replacing with “AFM” furnace with flush door.
  • Page 56 Literature number 33852 8500& 890 Series Furnaces RECESS PAN AND DOOR 1120 North Main Street • Elkhart, IN 46514 Phone: 1-866-869-3118 WWW.EDOMETIC.COM Installation Sheet RECESS MOUNTING BRACKET ONE EACH SIDE (6) MOUNTING SECREWS 9-7/8" 0.44 0.44 R 2-1/8" CORNER CUTOUT DETAILS 5/16"...
  • Page 57 Effective 9/16 EMAIL :CUSTOMERSUPPORTCENTER@DOMETIC.COM This instruction sheet is for use by an authorized service technician to install a Dometic furnace. Should you require further information, contact your dealer or nearest Dometic Service Center. Follow this installation instruction to insure safe operation of the furnace. Failure to install furnace according to this installation instruction nullifies the furnace warranty.
  • Page 58 STEP 4 STEP 1 Fasting Clips Cut OFF (4) tabs (2) Bend at 90° • Remove (4) of the six tabs located on the control box. Leave the two center tabs for mounting the door. Secure the furnace to coach floor with four screws •...
  • Page 59 • Improper installation, adjustment, alteration, service or casing. maintenance can cause injury or property damage. For assistance or additional information consult Dometic • Customer Service Department, a qualified installer or gas supplier. Follow directions exactly for proper installation, •...
  • Page 60 LITERATURE NUMBER MPD 38677 DOMETIC CORPORATION KIT EXTERNAL RELAY REPLACEMENT 1120 North Main Street. Elkhart, IN 46514-3203 Phone: 1-866-869-3118 DC IGNITION CONTROLS Internet: WWW.EDOMETIC.COM Email: CUSTOMERSUPPORTCENTER@DOMETIC.COM Effective 9/16 This kit contains a new DSI board that will function as a direct field 85-III &...

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