HeatingCodesTrane furnace blinking 3 times: draft pressure error
What three flashes mean
Trane's installer guide 18-CH49D1-1 defines 3 flashes as "Draft Pressure Error" and lists the possible problems as (a) venting problem, (b) pressure switch problem and (c) inducer problem. The furnace needs proof that the inducer is moving air before it will light the burners, and this code means that proof is missing.
How the three problem areas show up
| Trane lists | What that can look like | Who should check it |
|---|---|---|
| Venting problem | Blocked or damaged vent or combustion-air pipe, or a blocked termination outside | Homeowner can look at the outdoor ends from the ground; technician for the rest |
| Pressure switch problem | Switch will not close, or the tubing to it is disconnected or obstructed | Technician |
| Inducer problem | The draft inducer motor is not moving enough air | Technician |
Carrier's equivalent code, status code 32, gives a longer list that includes excessive wind, low inducer voltage and a plugged condensate system on condensing models. Goodman's manual explains that the furnace pressure switches watch airflow through the heat exchanger and guard against blocked condensate drain conditions. Use those as general background; Trane's table for this control is the three-item list above.
A winter note
Snow, ice, leaves or a nest at the outdoor vent or intake can restrict airflow. That is an example of a venting problem, not a statement from Trane's table. If you can see the pipe ends from the ground, look and clear what you can reach. If the vent runs through a roof, or you have to open any pipe, leave it for a technician.
Safe homeowner checks for a Trane furnace blinking 3 times
- Look at outdoor terminationsFrom the ground, check the vent and combustion-air pipe ends for snow, ice, leaves or nests and clear what you can reach safely.
- Restart onceSet the thermostat to off, wait a minute, then set it to heat and watch whether the code returns.
- Call a technician if it repeatsA repeat means the pressure switch, tubing or inducer needs a technician with the furnace manual.
Frequently asked questions
Can a dirty filter cause three flashes?
Trane's table does not list a dirty filter for this code; the cause is draft pressure (venting, pressure switch or inducer). A dirty filter is more associated with the open limit circuit code.
Is this safe to leave running?
The furnace will not fire while the code is active, which is the safe behavior. Do not try to force it to run. Use another safe heat source and leave generators and fuel-burning heaters outside or unused indoors.
Sources
- Installer's Guide 18-CH49D1-1: SiNi Igniter Assembly IGN00117 (includes the Integrated Furnace Control error flash codes) (Trane) Covers: Trane and American Standard furnaces using the Integrated Furnace Control (IFC) covered by this installer guide (dated 04/09). Newer boards can differ; check the wiring-diagram label inside your furnace.
- SP05-59 Service and Maintenance Procedures: Deluxe 4-Way Multipoise 2-Stage Direct-Vent Condensing Gas Furnace (Carrier (shareddocs.com)) Covers: Carrier 2-stage condensing gas furnaces with the status-code LED control described in the document. Other Carrier, Bryant and Payne boards can use different codes; check the service label on your furnace.
- RS6612023 Service and Troubleshooting: 34.5" Chassis ACVC96/AMVC96/GCVC96/GMVC96 Gas Furnaces (Goodman Manufacturing (Daikin)) Covers: Goodman and Amana 96% two-stage condensing furnaces in the 34.5" chassis.
Safety note: this page is general information drawn from the sources above. Gas, combustion and line-voltage repairs belong to a licensed professional. Your own equipment's label and manual take priority over anything here. Read the full disclaimer.