When your furnace stops turning on, blows cold air, or short cycles, our furnace guides help you diagnose the cause before you pay for a service call. Covering thermostats, ignition, flame sensors, error codes by brand, and honest repair costs — with clear guidance on when a problem needs a licensed HVAC pro.
Last updated: July 2026 · Reviewed against Carrier, Goodman and Trane service documentation Short cycling — when your furnace turns on and off every few minutes without completing a full heating cycle — is one of the most common furnace complaints, and one of the most important to fix quickly. Beyond the annoyance and the … Read more
Last updated: July 2026 · Reviewed against Carrier, Goodman and Trane service documentation Water pooling around your furnace is almost always one of two things: a clogged condensate drain on a high-efficiency furnace, or condensation from a problem with a standard-efficiency furnace’s flue. It is rarely an emergency, but you should find the source quickly … Read more
Last updated: July 2026 · Reviewed against Carrier, Goodman and Trane service documentation If you have no air at all rather than cold air, see furnace not blowing hot air. A furnace blowing cold air usually comes down to one of five things: a thermostat set to “ON” instead of “AUTO”, a dirty flame sensor … Read more
Last updated: July 2026 · Verified against Carrier, Trane and Goodman service documentation A furnace that will not turn on usually has a simple cause: a thermostat setting, a tripped breaker, a switched-off power switch, a dirty flame sensor, or a clogged filter that triggered a safety lockout. Most of these take five minutes and … Read more