Furnace Not Heating? What an HVAC Diagnostic Costs
Typical market range as of May 2026 · US market research
Most homeowners
$125
When your furnace is running but the house isn't warming up — or it clicks, lights briefly, and shuts back off — the first thing you pay for is a diagnostic: the tech's time and tools to find the actual fault before quoting a fix. A standard residential diagnostic visit typically runs $75–$200, with $125 being a common figure. Many techs credit that fee toward the repair if you approve the work the same day, so ask whether it's applied or charged on top.
What drives the price
After-hours & weekends
No-heat calls on nights, weekends, and holidays commonly run 1.5–2× the standard fee.
First hard freeze
The first cold snap of the season is the busiest window of the year for no-heat calls — fees and wait times both climb.
Credited vs. stacked
Some techs waive or credit the diagnostic if you book the repair; others charge both. Confirm up front.
Combustion checks
A simple no-heat check is quick; a combustion analysis or heat-exchanger inspection on an older furnace adds time and cost.
Regional context
In cold-winter markets, $99–$149 is the typical weekday diagnostic. Booking at the first sign of trouble — before the deep freeze — usually means a lower fee and a same-week slot.
Walk in informed
A diagnostic should produce a clear written finding — what's wrong and what the repair costs — before any work starts. A $250 ignition repair is not a reason to replace a furnace that's otherwise sound; be wary of a same-night pitch for a whole new system.
Fair Price Guide is iHVAC's market research for informational purposes and is strictly advisory. Actual prices are set by the independent technician. iHVAC is not a party to any transaction and assumes no liability, operating with zero middleman billing or liability.
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Common questions
Is the diagnostic fee credited toward the repair?
Often, but not always. Many techs apply it to the repair if you approve the work the same day. Ask before they start so there are no surprises on the invoice.
Why is my furnace running but blowing cold air?
Common causes are a dirty flame sensor or failed ignitor (the furnace lights then shuts off), a tripped limit or rollout switch, a blocked intake or exhaust pipe, a thermostat left in FAN ON, or a clogged filter. The diagnostic exists to tell you which one — and the repairs range from under $200 to a replacement conversation.
Should I keep trying to restart it?
One reset at the furnace power switch is fine. Repeated lockouts mean the furnace is protecting you from an unsafe condition — stop cycling it and get a diagnosis. If you ever smell gas or a CO alarm sounds, leave and call the gas utility from outside.
Related costs
How we research these numbers
This range is synthesized from published 2025–2026 US HVAC cost data and HVAC field knowledge. It's market reference — not a quote, and not a price iHVAC sets. As real techs complete jobs on iHVAC, these ranges will be backed by the actual local prices homeowners pay — the most accurate source there is.
References triangulated for this guide: