Eight Reasons Why a Furnace Pressure Switch Might Fail in Nicholasville, KY

Nothing is worse than waking up on a chilly winter morning and finding that your furnace won’t start. If your system suddenly stops working, the pressure switch—a critical safety component—might be to blame.
This small device ensures your furnace vents exhaust gases safely, but when it fails, your home’s warmth disappears. Understanding what causes a furnace pressure switch to fail helps you address issues before they escalate.
In this guide, Watson Heating & Air explores eight common culprits and how our HVAC services in Nicholasville, KY, keep your system running smoothly.
Four Mechanical Failures That Trigger Furnace Pressure Switch Problems
Your furnace’s pressure switch relies on precise mechanical operation. When these components falter, the switch can’t function properly. Here are four key mechanical issues common in Nicholasville homes:
- Inducer fan malfunction: The inducer fan pulls exhaust gases out of the furnace. If it’s clogged, worn, or damaged, it can’t create enough airflow to activate the pressure switch. This is a leading cause of unexpected shutdowns.
- Blocked exhaust flue: Debris, animal nests, or ice buildup in the flue, which are common during Kentucky’s harsh winters, restrict airflow. The pressure switch senses inadequate venting and shuts the furnace off to prevent carbon monoxide risks.
- Cracked suction tube: This tube connects the inducer fan to the pressure switch. Cracks or leaks disrupt airflow readings, causing the switch to misread conditions and halt operation.
- Damaged diaphragm flap: The diaphragm inside the pressure switch seals the electrical circuit. Wear, dirt, or moisture can cause it to stick or tear, preventing the switch from signaling the furnace to ignite.
Four Electrical and Wear-Related Issues Impacting Furnace Pressure Switches
A furnace's age, wiring problems, and routine wear also impact pressure switch reliability. Here’s what causes a furnace pressure switch to fail in Nicholasville homes:
- Loose electrical connections: Vibrations from daily use can loosen wires over time. Faulty connections interrupt the switch’s ability to communicate with the furnace, leading to erratic behavior or total failure.
- Worn-out pressure switch: Years of use can degrade the switch. A worn-out component may fail to close the circuit, even if other parts function correctly.
- Debris buildup in the switch: Dust, soot, or corrosion inside the switch can jam its internal mechanisms. This is common in systems that skip annual maintenance.
- Clogged condensate hose: High-efficiency furnaces produce condensation drained through a hose. If this hose clogs, water can back up into the pressure switch, damaging its components.
How To Prevent Furnace Pressure Switch Issues in Nicholasville Homes
What causes a furnace pressure switch to fail, and how can you avoid it? Proactive maintenance is the best way to prevent furnace pressure switch failures and keep your Nicholasville home warm.
Following an HVAC maintenance checklist helps catch these issues early. For example, cleaning the condensate hose or tightening electrical connections during a tune-up prevents costly repairs.
Small steps today can prevent big headaches tomorrow—and keep your furnace running smoothly through Nicholasville’s coldest days. Here’s how to protect your system year-round:
- Schedule annual professional tune-ups: During routine visits, a certified technician can inspect the inducer fan, test the pressure switch, and clear blocked exhaust flues.
- Clean the exhaust flue seasonally: To prevent airflow restrictions, remove leaves, debris, or animal nests from the flue opening, especially in fall and winter.
- Check hoses and tubes for damage: Inspect the suction tube and condensate drain hose for cracks or clogs, which disrupt pressure readings.
- Test electrical connections: Ensure wires to the pressure switch and inducer fan are secure to prevent loose electrical connections.
- Replace air filters regularly: Dirty filters strain the furnace, increasing debris buildup in the pressure switch and heat exchanger.
- Follow a maintenance plan: Stay ahead of wear and tear by adhering to a seasonal HVAC maintenance plan tailored to Kentucky’s climate.

Contact Watson Heating & Air – Your Furnace Pressure Switch Experts in Nicholasville
A malfunctioning furnace pressure switch can leave your Nicholasville home uncomfortably cold and put your family at risk. Issues like inducer fan malfunctions, blocked exhaust flues, cracked suction tubes, and loose electrical connections are common culprits. Debris buildup, damaged diaphragm flaps, worn-out switches, or clogged condensate hoses can also trigger failures—especially during Kentucky’s harsh winters.
Now that you know what causes a furnace pressure switch to fai, trust Watson Heating & Air to restore your comfort. We diagnose issues quickly, ensuring your Nicholasville home stays warm all winter. Our team also specializes in fixing furnace freezing problems to keep your system reliable year-round.
If your furnace fails, Watson Heating & Air provides fast, lasting repairs. Contact us today—we’re here to keep your family cozy and safe.










