It’s doing its job if it occasionally takes a trip. A deeper issue, such as limited airflow, a filthy filter, or a malfunctioning blower, is typically indicated by frequent tripping. Below, we explain the most common causes, what you can safely check yourself, and when it makes sense to have IRBIS furnace repair experts in San Jose take a closer look.
In This Article:
What Are the Signs That a Furnace Limit Switch Is Tripping?
The limit switch is used to control the temperature which is inside the furnace, and the burner is turned off when the temperature is too high. If it trips frequently, there are a few signs you’ll see.
Below are some furnace overheating causes:
- The machine may be switching on and off all the time.
- The machine may remain on even when the gas valves are shut off.
- The machine may be used often.
- Frequent cycling: Instead of following the regular heating cycles, the appliance is constantly turning on and off.
- Various temperatures: The room’s temperature may be quite different from one to another.
- Burning or smoky smell: Do not disregard any signs of overheating.
The limit switch itself may not necessarily be faulty. Often it’s reacting appropriately to too much heat due to another issue.
What Can You Check Before Calling an HVAC Professional?
The following are some basic checks, such as replacing a dirty furnace filter, that one can conduct before booking an appointment for services. These should only cover simple observations and not be used to make repairs or overrides to the furnace safety controls.
You can also check:
- Whether there is any obstruction, such as furniture preventing the supply and return-air vents.
- Having enough air circulation around the furnace
- If the return-air grille is blocked by something.
- If dust builds up in the accessible parts, whether this is evident around accessible areas
- If the furnace is showing an error code
With the furnace under inspection by one of the technical staff members of a company like IRBIS, it is easy for them to figure out if it is due to airflow, the blower assembly, the blower limit switch, or some other part.
Is It Safe to Keep Running a Furnace That Keeps Tripping the Limit Switch?
Turn off your furnace and schedule an examination if it is cycling on and off. This is especially important if you see any of the following:
- Smells of fire or electricity.
- Unusual noises
- Overheating of the furnace.
- Visible damage
- Smoke or indications of scorch.
- Repeated ignition problems
If it becomes necessary, evacuate and contact the emergency or utility service to report any possible leak of gas or carbon monoxide; do not try to turn it off or use the heating unit.
When Does a Tripping Limit Switch Require Professional Furnace Repair?
However, if basic airflow testing does not fix the problem and/or the furnace continues to turn on and off, then a diagnosis is necessary.
A technician can check:
- Ductwork and airflow to see if heated air is able to circulate properly.
- Blower motor/fan assembly (mechanical or electrical).
- The normally operating heat exchanger and burners should not exhibit any of these symptoms. These are characteristic of abnormal operation of a heat exchanger and burner.
- A limit switch to determine if it is working properly.
- Temperature readings to determine if the furnace is really hot.
- Oversee quality assurance of the control circuit and wiring for defects that may impact furnace operation.
Getting the right value for the limit switch is the key factor; however, switching the limit switch without knowing why it is tripping will not get you anywhere. The switch may just be switching because of some other fault.
How Can You Prevent Furnace Limit Switch Problems?
The typical lifespan for a furnace is between 15 and 20 years. However, proper maintenance will help prevent any airflow and overheating problems.
There are some things homeowners can do to help:
- Maintaining furnace filters by changing them on schedule per the manufacturer’s advice.
- Ensuring that supply and return vents remain clear.
- Having your furnace checked by a professional regularly
- Providing sufficient clearance near the furnace
- Detecting any abnormalities in odors, sounds, or airflow
- Getting to grips with heating issues instead of the constant resetting.
Professional maintenance may also detect emerging issues, such as restricted airflow in the furnace, prior to multiple overheating instances. A technician may monitor safety controls, combustion, moving parts, electrical connections, and airflow during an inspection.
Conclusion
A furnace limit switch that is tripping is commonly an indication of the problem and not the problem itself. One potential cause of repeated shutdowns is restricted airflow caused by a dirty furnace filter; however, problems with the furnace, ductwork, blower, or switch may also be the cause.
A professional diagnosis will establish what’s causing the issue and get it fixed so safe and reliable heating can resume.
