Suburban RV Furnace Repair Manual

The Suburban RV Furnace is a forced-air heating system designed for recreational vehicles, providing reliable warmth in various weather conditions. This manual covers NT Series, SF Series, and other popular Suburban furnace models with features including electronic ignition, multi-speed blower, safety shut-off, thermostat control, and LP gas operation. Below are essential sections for safety procedures, troubleshooting, maintenance, repair steps, and technical specifications.

1. Safety Precautions 2. Model Identification 3. Basic Operation 4. Troubleshooting Guide 5. Common Repairs 6. Component Replacement 7. Maintenance Schedule 8. Electrical System 9. Gas System 10. Technical Specifications 11. Warranty Information

Safety Precautions

Critical safety measures before performing any furnace maintenance or repairs.

Safety Step	Description
Gas Supply Shut-off	Turn off LP gas at main tank valve before servicing
Electrical Disconnect	Disconnect 12V DC power from RV electrical system
Ventilation	Ensure adequate ventilation when testing gas system
Carbon Monoxide	Install and test CO detectors; never block vents
Fire Safety	Keep combustible materials away from furnace
Personal Protection	Wear safety glasses and gloves during repairs

Model Identification

Locate your furnace model number for proper parts identification.

Find model plate: Located on furnace exterior or interior access panel.
Common models: NT-16SEQ, NT-20SEQ, NT-30SEQ, SF-20FQ, SF-30FQ.
Record serial number: Required for warranty claims and parts ordering.
BTU ratings: Range from 16,000 to 40,000 BTU depending on model.

WARNING! Using incorrect parts can cause furnace malfunction and safety hazards.

Basic Operation

Understanding normal furnace operation sequence.

Thermostat call: Set thermostat above room temperature.
Ignition sequence: Blower starts, sail switch activates, igniter glows.
Gas valve opens: Gas flows to burner, ignition occurs.
Heat production: Burner heats heat exchanger, blower circulates warm air.
Shut-down: Thermostat satisfied, gas valve closes, blower continues cooling.

CAUTION! If furnace fails to ignite after three attempts, lockout occurs requiring reset.

Troubleshooting Guide

No heat: Check thermostat, gas supply, 12V power, fuse.
Blower runs, no ignition: Sail switch, igniter, gas valve issues.
Short cycling: High limit switch, blocked vents, airflow problems.
Unusual odors: Dust buildup, combustion issues, gas leaks.
Error codes: Blinking LED indicates specific fault conditions.
No blower operation: Blower motor, control board, wiring problems.

Common Repairs

Step-by-step procedures for frequent furnace issues.

Igniter Replacement: Remove burner assembly, disconnect wires, install new igniter.

Blower Motor: Access motor compartment, disconnect electrical, remove mounting bolts, replace motor.

Sail Switch: Test for continuity, replace if faulty, ensure proper airflow activation.

Thermostat: Check wiring, replace batteries, test temperature calibration.

Control Board: Diagnose with multimeter, note wiring positions, install replacement board.

Component Replacement

Detailed replacement procedures for major components.

Turn off all power and gas supply before disassembly.
Remove furnace access panel and disconnect electrical connections.
Label all wires and connections for proper reassembly.
Install new component following reverse removal procedure.
Test operation before securing access panels.

Tip: Take photos during disassembly for reference during reassembly.

Maintenance Schedule

Regular maintenance ensures optimal furnace performance and safety.

Annual inspection: Before each heating season.
Burner cleaning: Remove debris from burner assembly.
Vent system: Check for obstructions in intake and exhaust.
Blower wheel: Clean dust and debris accumulation.
Electrical connections: Tighten loose terminals and connections.
Gas connections: Check for leaks with soap solution.
Air filters: Clean or replace as needed for proper airflow.

WARNING! Never operate furnace with blocked vents or damaged components.

Electrical System

12V DC electrical system components and testing procedures.

Component	Function	Test Procedure
Control Board	Manages furnace operation	Check for 12V input/output, LED codes
Blower Motor	Circulates air	Test resistance, check for 12V power
Igniter	Heats to ignite gas	Check for glow, test resistance (40-100 ohms)
Sail Switch	Detects airflow	Test continuity when activated
Limit Switches	Safety temperature control	Test continuity at room temperature

Gas System

LP gas system components and safety checks.

Gas Valve: Controls gas flow to burner; test solenoid operation.

Burner Assembly: Mixes gas and air; clean ports annually.

Manifold Pressure: Typically 11" water column; adjust if necessary.

Gas Leak Test: Use soap solution on all connections; bubbles indicate leaks.

Venturi Tube: Ensures proper air/gas mixture; keep clean and unobstructed.

Technical Specifications

Fuel Type: Liquid Propane (LP) Gas
Electrical: 12V DC, 3-10 amps depending on model
BTU Ratings: 16,000 - 40,000 BTU/hour
Efficiency: 85-92% AFUE depending on model
Vent Size: 3" or 4" diameter depending on BTU rating
Dimensions: Varies by model; typically 12"W x 18"H x 9"D
Weight: 15-25 pounds depending on model
Sound Level: 55-65 dB during operation

Warranty Information

Component	Warranty Period	Coverage
Heat Exchanger	10 years	Limited warranty against defects
Other Components	2 years	Parts and labor coverage
Control Board	2 years	Replacement for manufacturing defects
Labor	1 year	Authorized service center repairs

Registration: Complete warranty registration within 30 days of installation.

Service: 1-800-496-8344; www.suburbanrv.com