When something’s wrong with your HVAC system, one of the first places to check is your thermostat. Most models use a digital display that will display a specific numerical error code. This error code can be used to help determine the problem and speed up the troubleshooting and repair process for HVAC systems like your furnace.
This is even simpler with smart thermostats like the Lennox iComfort model. Let’s take a look at three serious error codes—411, 225 and 31—to find out what the problem is. We’ll also share what steps your technician will take to resolve the problem, and the possible costs to do so.
Solving Error Code 411
Error code 411 is an urgent priority to take care of. You’ll see this error code appear when the outdoor unit’s low-pressure switch malfunctions five times or more during one heating or cooling cycle. Since this error code includes the outdoor unit, it may be involved with your air conditioner. Each time the low-pressure switch opens incorrectly, the error count increases. Once it reaches five strikes, the thermostat automatically turns down the outdoor unit. This is known as a lockout and is a safety feature intended to minimize damage.
Fixing the Problem
A technician will test the system charge using several methods, as the issue may be with the switch’s power connections instead of the low-pressure switch on its own. Once the cause has been uncovered, technicians can reset the outdoor unit by putting it in test mode or by resetting low-voltage power. Once the issue is repaired, the error code should automatically clear.
Estimated Repair Cost
Replacing a low-pressure shutoff switch may depend on the specific model of your outdoor unit. You could expect to pay between $200 to more than $600 depending on parts and air conditioning repair costs. The shutoff switch itself runs an average of $30 to $150.
Lennox Thermostat iComfort Error Code 225
Error code 225 is specific to your furnace, particularly the high-pressure switch. This switch is a safety feature that releases high pressure inside the furnace, such as when airflow is blocked. When this error code appears, it means the pressure switch will not close. Without consistent airflow and pressure, the furnace won’t function as efficiently.
Fixing the Problem
The technician will monitor the high-pressure switch to determine how it functions. They’ll measure the pressure while it attempts to close during a heating cycle as well as its general operating pressure. If they find a problem, an obstruction preventing airflow is the most likely culprit. There are a few places to check, such as the vent and combustion air inducer. Technicians will look at both these components as well as the condensate drain to locate the blockage.
Estimated Repair Cost
Because there are a few places to inspect before an obstruction can be found, labor costs should be considered when resolving error code 225. Ultimately, the final cost of this furnace repair will depend on where the problem is found as well as how long it takes the technician to determine the source.
Clearing Error Code 31
Seeing error code 31 on your thermostat means it hasn’t been able to communicate with your furnace for more than three minutes. Multiple components communicate with the thermostat, so you may find this error code when any of them malfunction or fail. Most of the time this can be traced back to an electrical problem, like damaged wiring or a loose connection.
Fixing the Problem
A technician can review all the connections and wiring of the communicating components of your furnace. They will test voltages and wiring ohms as especially high resistance can result in a disconnection. With a special tool called a multimeter, technicians can narrow down where the disruption originated from. Sometimes this is the furnace’s float switch, a component that shuts down the furnace when the condensate drain pan is too full.
Estimated Repair Cost
With several potential causes, it may be difficult to estimate the total repair costs of error code 31. Technicians will inspect the float switch to rule it out before systematically reviewing electrical wiring and connections. If the cause is damage or a failed component, replacement part costs should be included. You might expect to spend anywhere from $200 to more than $800 for higher-range models.