Goodman Furnace Pressure Switch Location and How to Access It
Locating the pressure switch on a Goodman furnace is essential for troubleshooting and maintenance. The pressure switch is a safety device that ensures the furnace’s combustion process operates correctly by detecting proper airflow through the venting system. This article provides a comprehensive guide to the location, function, and inspection of the Goodman furnace pressure switch, helping homeowners and HVAC technicians perform routine checks and resolve common issues efficiently.
| Component | Location | Function | Common Issues |
|---|---|---|---|
| Pressure Switch | Near the inducer blower assembly on the furnace | Detects proper venting and airflow for safe ignition | Clogged intake tube, faulty switch, blocked vent |
| Inducer Blower | Top or side of the furnace cabinet | Moves combustion gases through the vent | Failure causes pressure switch issues |
| Pressure Tubing | Connected to the pressure switch and inducer housing | Transmits differential pressure to the switch | Cracks or disconnections prevent switch operation |
Where to Find the Pressure Switch on a Goodman Furnace
The pressure switch is typically located near the inducer blower motor on Goodman furnaces. Depending on the model, you can find the inducer and the attached pressure switch either on the top or sometimes on the side of the furnace cabinet. The pressure switch is a circular or oval-shaped device with one or two vacuum tubes connected to it and electrical terminals for wiring.
In many Goodman furnaces, the pressure switch is mounted on the side of the inducer blower housing, which is itself attached to the burner compartment. This positioning allows the switch to sense the negative pressure created by the inducer before the ignition sequence starts.
How the Pressure Switch Functions in a Goodman Furnace
The pressure switch measures the vacuum created when the inducer blower activates and the venting system is clear. When the furnace calls for heat, the inducer motor powers on, pulling air through the vent flue. This negative pressure is transmitted through flexible pressure tubing to the pressure switch, signaling it to close and allow the ignition process to proceed.
If the vent or inducer system is blocked or malfunctioning, the switch does not close, preventing the furnace from igniting and protecting against dangerous gas buildup.
Identifying the Pressure Switch and Related Components
Appearance and Connection Points
- Round or oval device with electrical terminals: Usually fitted with two or three vacuum ports.
- Rubber or plastic pressure tubing: Connects the switch to the inducer housing or vent pressure point.
- Wiring harness: Attaches to the electrical terminals, often secured with spade connectors.
Common Goodman Furnace Models and Their Switch Locations
| Model Series | Pressure Switch Location | Notes |
|---|---|---|
| GMVM, CMVM Series | Side of inducer blower housing | Accessible by removing furnace front panel |
| GMVC Series | Mounted near inducer assembly on top | Requires removal of blower access panel |
| GMSS Series | Attached directly to inducer motor housing | Mounted with vacuum tubing facing inducer vent |
How to Access the Pressure Switch on a Goodman Furnace
Accessing the pressure switch involves these steps:
- Turn off the power: Always switch off electrical power to the furnace at the breaker panel before attempting any maintenance.
- Remove the furnace access panel: Most Goodman furnaces have a front or side access panel secured by screws or clips. Remove it carefully to expose internal components.
- Locate the inducer motor: The inducer blower is usually near the top of the combustion chamber and adjacent to the vent pipe.
- Find the pressure switch: Look for a small round device attached to or near the inducer blower with pressure tubing connected to it.
- Inspect pressure tubing: Check for any signs of cracks, blockages, or disconnections in the tubing that can affect switch function.
Common Issues with the Goodman Furnace Pressure Switch
The pressure switch may fail to close or malfunction due to several issues:
- Clogged or blocked vent pipe: Debris, bird nests, or ice can restrict airflow, preventing proper pressure detection.
- Damaged or cracked pressure tubing: Air leaks in the tubing result in incorrect pressure readings to the switch.
- Faulty switch contacts: Electrical components inside the switch can wear out or fail over time.
- Inducer motor failure: If the inducer blower doesn’t start, the pressure switch will not sense proper pressure.
Testing and Replacing the Pressure Switch
To check the pressure switch operation:
- Disconnect power and pressure tubing: Remove the tubing carefully without damaging it.
- Use a multimeter to test continuity: Place probes on the switch terminals; it should show continuity when the inducer runs.
- Inspect switch ports for debris: Clean as necessary.
- Replace switch if faulty: Ensure to purchase a Goodman-specific replacement switch matching your furnace model.
Maintenance Tips to Keep the Pressure Switch Functioning
- Regular inspection of vent pipes: Clear any obstructions periodically, especially in outdoor vent terminations.
- Check and replace pressure tubing: Replace brittle or cracked tubes every few years.
- Schedule professional furnace service: Annual HVAC maintenance can detect early pressure switch problems.
- Keep the inducer blower clean: Ensure no debris interferes with the inducer motor operation.