Carrier furnace troubleshooting
If your Carrier furnace is giving you trouble, fixing the problem may be as simple as updating your thermostat settings. Or you may need a hand from a local HVAC pro. Before you pay a service fee, give these Carrier furnace troubleshooting tips a try.
Carrier furnace is not heating or not blowing hot air
Check the air filter; it may be dirty. It’s time to change your filter if it’s gray with a dusty buildup.
Carrier furnace is cycling irregularly
Dirty filters are the most common cause of furnace cycling issues. Per the instructions above, replace your furnace filter if it’s dirty.
Next, check your thermostat. Turn it off and restart it. Try changing the batteries if it takes them.
Finally, make sure your windows and doors are properly sealed and not leaking air. The Department of Energy has good information on how to detect air leaks.
Carrier furnace is starting and stopping
Set the thermostat to “heat” and either “on” or “auto.” See if the air filter is clean. You may need to replace it with a fresh one.
If the furnace is still not working correctly, make sure all the vents in your home are open and unobstructed.
Carrier furnace is leaking water
In most cases, furnaces leak water because of a clogged condensation drain. This (and any other furnace water leak causes) is best repaired by a professional.
When you notice water leaking from your furnace, turn off the heat via the thermostat. Then turn off the power switch and electrical breaker connected to the furnace. Water plus electricity is a dangerous combination. If you have a gas furnace, turn off the gas line.
Mop up the excess water to avoid water damage and call a certified HVAC technician for repair.
Carrier furnace troubleshooting codes
Your system may be able to help you diagnose the problem when you’re Carrier furnace troubleshooting. Some standard Carrier furnace error codes follow.
|Carrier furnace error code||What it means|
|Blinking yellow 3||Stuck in high fire mode|
|Blinking green 4||Stuck in low fire mode|
|11||No faults in recent history|
|12||Blower calibration lockout|
|13||Limit switch lockout|
|21||Invalid model selection|
|23||Invalid blower airflow selection|
|24||Secondary voltage fuse is open|
|31||High-pressure switch fault|
|32||Low-pressure switch fault|
|33||Limit switch fault|
|34||Ignition proving fault|
|41||Blower outside valid speed range|
|42||Inducer outside valid speed range|
|43||Pressure switch calibration fault|
|44||Blower calibration fault|
Check the error code so you know what to expect before calling a professional for service.
Carrier furnace troubleshooting: model lookup
We’ve provided links to the product documentation for Carrier’s current furnace lineup to get you started.
Carrier furnace troubleshooting documentation
Don’t see your model listed? Look it up here.
When to call an HVAC professional
Call an HVAC technician when you’ve tried the Carrier furnace troubleshooting tips above and still can’t solve the problem.
Or, if you’re uncomfortable performing Carrier furnace troubleshooting, a technician can do it for you.
Click below to connect with a local HVAC pro who can help.
DIY didn’t do it for you?