Goodman Furnace Manual GMS90904CXA

The Goodman GMS90904CXA is a high-efficiency gas furnace with AFUE rating up to 90%, multi-speed blower motor, electronic ignition system, aluminized steel heat exchanger, built-in draft inducer, and compatibility with standard thermostat systems. Designed for residential heating applications with natural gas or propane capability. Below are key sections for safety, features, installation, operation, maintenance, and troubleshooting.

Features at a Glance

Key components: Aluminized steel heat exchanger, multi-speed direct drive blower, hot surface ignitor, induced draft combustion system, flame sensor, pressure switches.

Installation Requirements

Professional installation required. Verify local codes and obtain permits.

1. Location: Install in clean, dry area with proper clearances (minimum 1 inch from combustible materials).
2. Venting: Use approved PVC pipe for combustion air and flue gas.
3. Gas Supply: Connect to proper gas line with sediment trap and shutoff valve.
4. Electrical: Connect to 120V AC power with proper grounding.
5. Ductwork: Ensure proper return and supply air duct connections.

WARNING! Gas appliances can be dangerous; installation must be performed by qualified technician. Ensure proper ventilation to prevent carbon monoxide buildup.

First-Time Setup

After installation, perform initial startup procedure.

1. Verify all connections: Gas, electrical, venting, and ductwork.
2. Install air filter: Ensure proper size and orientation.
3. Gas pressure check: Measure and adjust manifold pressure per specifications.
4. Startup sequence: Turn on power and gas supply, set thermostat to heat mode.
5. Check operation: Verify proper ignition, heating, and blower operation.

CAUTION! Never operate furnace without proper venting and air filter installed.

Specifications

• Model: GMS90904CXA
• Input BTU/H: 90,000 BTU
• Output BTU/H: 81,000 BTU
• AFUE Rating: Up to 90%
• Gas Type: Natural Gas (convertible to LP)
• Electrical: 120V AC, 60Hz
• Blower Speeds: Multi-speed for heating and continuous fan
• Dimensions: Standard upflow configuration
• Venting: Category IV, PVC pipe required
• Warranty: Limited lifetime heat exchanger, 10-year parts

Controls and Settings

Integrated control board with LED diagnostic lights. Access door safety switch prevents operation when door removed.

Control Board: LED status lights indicate system operation and fault codes. Gas Valve: Manual shutoff and pressure regulation. Blower Speed Taps: Multiple speed settings for heating operation.

Thermostat Settings: Compatible with most 24V thermostats. Heating setpoint, fan control (auto/on). Limit Switches: High temperature safety cutoffs. Pressure Switches: Verify proper vent draft.

Connecting Thermostat

Standard 24V thermostat connections at control board.

1. Turn off power to furnace at electrical disconnect.
2. Remove control board cover to access thermostat terminals.
3. Connect thermostat wires: R (24V), W (heat), G (fan), C (common).
4. Secure connections and replace cover.
5. Restore power and test thermostat operation.

Tip: Use 18-gauge thermostat wire for reliable connections.

Operating Procedures

Normal heating operation controlled by thermostat.

1. Set thermostat to desired temperature and HEAT mode.
2. Furnace initiates startup sequence: draft inducer starts, pressure switch verifies draft.
3. Hot surface ignitor heats up, gas valve opens for ignition.
4. Flame sensor confirms burner operation.
5. Blower motor starts after heat exchanger warm-up delay.
6. When thermostat satisfied, gas valve closes, blower continues for cool-down.

WARNING! If you smell gas, immediately turn off gas supply and call qualified technician.

Maintenance Schedule

Regular maintenance ensures efficient and safe operation.

• Monthly: Check air filter, replace if dirty
• Annually: Professional inspection and cleaning
• Seasonal: Check vent system for obstructions
• Every 5 years: Heat exchanger inspection

Care & Cleaning

Turn off power and gas supply before servicing.

1. Air Filter: Replace every 1-3 months depending on usage.
2. Burners: Clean annually to remove dust and debris.
3. Blower: Vacuum blower wheel and housing annually.
4. Vent System: Inspect for obstructions or damage.
5. Drain System: Clear condensate drain line as needed.

CAUTION! Only qualified technicians should perform internal cleaning and adjustments.

Regulatory Information

ANSI Z21.47/CSA 2.3: Certified for natural and propane gas operation. UL listed. Manufactured to comply with U.S. safety standards. For technical support, contact Goodman Manufacturing at 1-877-GOODMAN or visit www.goodmanmfg.com. Serial number located on unit rating plate.

Troubleshooting

LED Codes: Blink patterns indicate specific fault conditions (refer to control board chart).

Service: 1-877-GOODMAN; www.goodmanmfg.com