When something’s wrong with your HVAC system, one of the first places to check is your thermostat. Most models have a digital display that will display a specific numerical error code. This error code can be used to help diagnose the problem and streamline the troubleshooting and repair process for HVAC systems like your furnace.
This is even easier with smart thermostats like the Lennox iComfort model. Let’s take a look at three serious error codes—411, 225 and 31—to learn what the problem is. We’ll also cover what steps your technician will take to resolve the problem, and the potential costs to do so.
Solving Error Code 411
Error code 411 is an urgent priority to resolve. You’ll see this error code appear when the outdoor unit’s low-pressure switch malfunctions five times or more throughout one heating or cooling cycle. Since this error code involves the outdoor unit, it can 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 shuts down the outdoor unit. This is known as a lockout and is a safety feature intended to prevent damage.
Fixing the Problem
A technician will test the system charge using several methods, as the issue could be with the switch’s power connections rather than the low-pressure switch on its own. Once the cause has been uncovered, technicians can reset the outdoor unit by placing it in test mode or by resetting low-voltage power. Once the issue is fixed, the error code should automatically disappear.
Estimated Repair Cost
Swapping out a low-pressure shutoff switch may depend on the specific model of your outdoor unit. You may expect to pay between $200 to more than $600 depending on parts and air conditioning repair costs. The shutoff switch itself costs an average of $30 to $150.
Solving Error Code 225
Error code 225 is specific to your furnace, namely the high-pressure switch. This switch is a safety feature that releases high pressure within the furnace, such as when airflow is blocked. When this error code appears, it means the pressure switch won’t close. Without consistent airflow and pressure, the furnace won’t perform as efficiently.
Fixing the Problem
The technician will watch the high-pressure switch to evaluate how it functions. They’ll measure the pressure while it tries to close during a heating cycle as well as its general operating pressure. If they notice a problem, an obstruction impacting airflow is the most common culprit. There are a few places to look, such as the vent and combustion air inducer. Technicians will check both these components as well as the condensate drain to locate the blockage.
Estimated Repair Cost
Because there are multiple places to inspect before an obstruction can be found, labor costs should be considered when resolving error code 225. Ultimately, the total cost of this furnace repair will depend on where the problem is located 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 issue, like old 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 should test voltages and wiring ohms as especially high resistance can result in a disconnection. With a special tool called a multimeter, technicians can pinpoint 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 overflowing.
Estimated Repair Cost
With multiple possible causes, it can be difficult to determine the total repair costs of error code 31. Technicians will check the float switch to rule it out before thoroughly reviewing electrical wiring and connections. If the cause is damage or a failed component, replacement part costs should be included. You may expect to spend anywhere from $200 to more than $800 for higher-range models.
