Fix it yourself, or call someone who actually knows the job.
Every guide works the causes in the order a technician would, names the ones you can close yourself for nothing, and gives the 2026 price of the ones you cannot, so an estimate is something you read rather than guess at.
Mike Kovacs HVAC technician, 20 years field experience Checked against manufacturer manuals and current contractor pricing. Editorial policy.
What we cover
Four rooms of the house, each with its own hub: the faults we walk through, and what the repair costs when it is not yours to make.
- 1 guide
Furnace
Heating faults, ignition problems, and what a repair really costs.
- Will not start
- Ignitor and flame sensor
- Short cycling
- Repair vs replace
- 2 guides
Water heater
Leaks, no hot water, and when a tank is past saving.
- Leaks
- No hot water
- Pilot and thermocouple
- Tank vs tankless
- 1 guide
Air conditioning
Cooling failures, airflow issues, and refrigerant questions.
- Not cooling
- Frozen coil
- Refrigerant
- Condenser faults
- 2 guides
Home costs
What US homeowners actually pay, by material and by region.
- Roof replacement
- Labor per square
- By region
- Estimate red flags
Repair, or call. Every guide tells you which.
The point is not to turn you into a technician. It is to stop you paying a service call for a two-minute fix, and to stop a bad contractor charging you for a job that was never needed.
When it is yours to fix
A good share of the faults that stop a furnace or a water heater cost nothing to put right. A fouled flame sensor is a scuff with an abrasive pad. A blower door left unseated after a filter change cuts the power by design. Each guide works the causes in the order a technician would, and names the ones you can close yourself.
- Flame sensor, scuffed clean by you
- $0
- Same fault, service call
- $80–$250
When it is a job for a licensed pro
Behind a sealed burner assembly, inside a refrigerant circuit, on the line side of a disconnect: that is licensed work, and we say so instead of talking you into it. What you get here is the number: what the job runs in 2026, by part and by region, so you can read an estimate instead of guessing at it.
- Hot-surface ignitor, installed
- $150–$300
- Control board, installed
- $400–$700