AC & Furnace Problem Finder
AC blowing warm air, furnace not heating, ice on the lines or water by the unit? Answer 5 quick questions and the finder ranks the likely causes as you go, then shows how urgent it is, what you can check yourself and what the repair should cost.
Last reviewed September 2026
Question 1 of 5
Do you smell gas or burning, or is a carbon monoxide alarm sounding?
AC and furnace repair costs by problem
| Problem | DIY difficulty | Pro repair cost |
|---|---|---|
| Clogged air filter | Easy | $75–$200 |
| Outdoor unit not running (capacitor or contactor) | Pro only | $100–$400 |
| Low refrigerant (refrigerant leak) | Pro only | $200–$1,600 |
| Frozen evaporator coil | Easy | $150–$650 |
| Clogged condensate drain | Easy | $75–$500 |
| Thermostat problem | Easy | $85–$300 |
| Furnace not igniting (ignitor or flame sensor) | Moderate | $150–$600 |
| Blower motor not working | Pro only | $400–$2,300 |
| Heat pump not heating well | Moderate | $150–$650 |
Got an HVAC quote? Check if it's fair
Typical professional price for this job: $75–$200
Heating and cooling questions
What should I check before calling an HVAC technician?
Check the thermostat mode, setpoint and batteries, the breaker and the furnace power switch, and the air filter. Those three fix a surprising number of 'broken' systems and can save a service call.
Why is my AC running but not cooling the house?
The most common causes are a clogged air filter, an outdoor unit that isn't running (often a failed capacitor), a frozen coil, or low refrigerant from a leak.
When is a heating or cooling problem an emergency?
A gas smell, a carbon monoxide alarm or a burning electrical smell are emergencies: leave the house or shut the system off and call for help. No heat in freezing weather also needs a fast repair to protect people and pipes.