American Standard Furnace Repair Manual

The American Standard Furnace is a high-efficiency heating system designed for residential and light commercial applications. This manual covers gas and electric furnace models with features including variable-speed blowers, electronic ignition systems, heat exchangers, safety controls, diagnostic LEDs, and energy-efficient operation. Below are key sections for safety procedures, system overview, installation guidelines, maintenance, troubleshooting, and repair instructions.

1. Safety Precautions 2. System Overview 3. Installation Guidelines 4. Technical Specifications 5. Control Systems 6. Maintenance Procedures 7. Diagnostic Codes 8. Common Repairs 9. Parts Replacement 10. Warranty Information 11. Troubleshooting Guide

Safety Precautions

Critical safety measures for furnace operation and repair.

Safety Measure	Description
Gas Shutoff	Always turn off gas supply before servicing
Electrical Disconnect	Switch off power at circuit breaker
Carbon Monoxide Detection	Install CO detectors near furnace area
Fire Extinguisher	Keep Class ABC extinguisher nearby
Ventilation	Ensure proper airflow and clear vents
Personal Protective Equipment	Wear safety glasses and gloves
Heat Exchanger Inspection	Check for cracks before operation
Gas Leak Detection	Use soap solution to check connections

Installation

Proper installation procedures for American Standard furnaces.

Location Selection: Choose well-ventilated area with clearance requirements met
Gas Line Connection: Use approved pipe thread compound on all connections
Electrical Wiring: Follow NEC codes and manufacturer specifications
Vent System: Install according to local codes and manufacturer guidelines
Ductwork: Ensure proper sizing and sealing
Combustion Air: Provide adequate fresh air supply

WARNING! Improper installation can cause fire, explosion, or carbon monoxide poisoning. Always hire qualified technicians.

First-Time Setup

Initial startup and configuration procedures.

System Check: Verify all connections are secure and proper
Gas Pressure Test: Measure and adjust manifold pressure
Ventilation Test: Check draft and combustion air flow
Electrical Test: Verify voltage and amperage readings
Ignition Sequence: Observe startup cycle for proper operation
Temperature Rise: Measure and adjust blower speed if needed
Safety Controls: Test limit switches and pressure switches

CAUTION! Never bypass safety controls during testing. Always follow manufacturer specifications.

Specifications

Fuel Types: Natural Gas, Propane
Efficiency Ratings: 80% AFUE to 98% AFUE models available
Heating Capacity: 40,000 to 120,000 BTU/h
Blower Motors: Variable-speed ECM technology
Ignition Systems: Hot surface ignition
Voltage Requirements: 120V AC, 60Hz
Vent Types: Category I and IV venting systems
Warranty: Limited lifetime heat exchanger warranty

Controls and Settings

Furnace control system operation and configuration.

Control Board: Integrated furnace controller with diagnostic LED, dip switch settings, terminal connections for thermostat, pressure switches, gas valve, igniter, and blower motor.

Thermostat Settings: Heat/Cool/Auto modes, temperature setpoints, fan control. Diagnostic Codes: LED flash patterns indicate specific error conditions. Dip Switches: Heat/cool staging, blower delays, accessory configuration. Safety Controls: Rollout switches, pressure switches, high-limit switches, flame sensor.

Connecting Devices

Proper connection of furnace components and accessories.

Thermostat Wiring: Connect R, W, Y, G, C terminals according to system type
Humidifier: Install and wire to HUM terminal if equipped
Electronic Air Cleaner: Connect to appropriate accessory terminals
Zone Controls: Wire zone panel according to manufacturer instructions
Venting: Connect flue pipes and combustion air intake

Tip: Always verify wiring with ohmmeter before applying power.

Maintenance Procedures

Regular maintenance tasks for optimal furnace performance.

Filter Replacement: Change every 1-3 months depending on usage
Blower Cleaning: Vacuum and wipe blower assembly annually
Heat Exchanger Inspection: Check for cracks or corrosion
Flame Sensor Cleaning: Remove and clean with emery cloth
Burner Cleaning: Remove debris from burner ports
Vent System Inspection: Check for blockages or damage
Electrical Connections: Tighten all terminal connections
Gas Valve Operation: Test for proper opening and closing

WARNING! Always disconnect power and gas supply before performing maintenance.

Diagnostic Features

LED diagnostic codes and troubleshooting indicators.

LED Flash Pattern	Fault Code	Description
1 Flash	Lockout	Ignition failure
2 Flashes	Pressure Switch	Pressure switch stuck open
3 Flashes	Limit Circuit	High limit switch open
4 Flashes	Flame Loss	Flame sensed when not called
5 Flashes	Rollout Switch	Rollout switch open
Continuous On	Normal	Proper operation

Care & Cleaning

Proper cleaning procedures for furnace components.

Use soft brush and vacuum for blower assembly. Clean flame sensor with fine sandpaper. Wipe burners with dry cloth. Clean condensate drain with vinegar solution. Never use water or cleaning solvents on electrical components.

CAUTION! Do not use compressed air on heat exchanger. Avoid damaging fragile components.

Regulatory Information

ANSI Z21.47: Certified for gas-fired central furnaces. UL 1995: Standard for heating and cooling equipment. Energy Star: Qualified models meet efficiency requirements. All installations must comply with local building codes and NFPA 54. For technical support, contact American Standard at 1-800-572-1111 or visit www.americanstandardair.com.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Furnace won't start	Power, thermostat, door switch	Check circuit breaker, thermostat settings, door switch engagement
No heat	Gas supply, igniter, flame sensor	Verify gas valve open, check igniter continuity, clean flame sensor
Short cycling	Dirty filter, limit switch	Replace air filter, check high limit switch operation
Blower won't stop	Thermostat, control board	Check thermostat fan setting, test control board relay
Unusual noises	Blower, inducer motor	Inspect blower wheel balance, check inducer motor bearings
Pilot won't light	Gas valve, thermocouple	Test gas valve operation, replace thermocouple if weak

Reset Procedure: Turn thermostat to off, wait 30 seconds, turn back to heat.

Service: 1-800-572-1111; www.americanstandardair.com