Repair service
HVAC & Water Heater Repair in Sonoma & Marin
Fast, honest repairs for heating, cooling, and hot water.
The short answer
Green Core Heating & Air repairs heat pumps, air conditioners, furnaces, ductless mini splits, ductwork, Harvest Thermal systems, and heat pump, tankless, gas, and electric water heaters across Sonoma and Marin counties. Our phones are answered 24/7, we aim to get out same-day or next-day for urgent calls depending on the season, and you get a written price before any work starts.
For urgent calls, we aim to get out same-day or next-day depending on the season, and you'll always get a straight answer about whether a repair makes sense or replacement is the better investment. Our phones are answered 24/7, so call (707) 988-5858 any time and we'll book the earliest available visit.
Every system we work on
What we repair
Heating & cooling
Heat Pumps
Not heating or cooling, frozen outdoor coils, short cycling, error codes, and refrigerant leaks.
More about heat pumpsAir Conditioning
Warm air from the vents, failed capacitors and contactors, refrigerant leaks, and frozen coils.
More about air conditioningFurnaces
No heat, ignition and flame sensor problems, failed blower or inducer motors, and short cycling.
More about furnacesMini Splits
Indoor units not heating or cooling, water dripping from the head, error codes, and sensor issues.
More about mini splitsDuct Work
Disconnected, crushed, or leaky ducts that leave rooms hot, cold, or dusty.
More about duct workHarvest Thermal
Diagnostics and repairs for Harvest Thermal heating, cooling, and hot water systems.
More about harvest thermal
Water heating
Heat Pump Water Heaters
Lukewarm water, error codes, clogged condensate drains, and fan or compressor problems.
More about heat pump water heatersTankless Water Heaters
Error codes, fluctuating temperatures, scale buildup, and ignition or venting problems.
More about tankless water heatersGas Water Heaters
No hot water, pilot and gas valve problems, leaking tanks or valves, and venting issues.
More about gas water heatersElectric Water Heaters
Failed heating elements and thermostats, tripped breakers, and sediment buildup.
More about electric water heaters
How it works
What to expect.
- 1
Call or book online
Call (707) 988-5858 or tap Book Now. Our phones are answered 24/7.
- 2
Find the real problem
We test the whole system, not just the part that failed, so the fix lasts.
- 3
Clear options first
You get a written price before any work starts, plus an honest recommendation if replacing makes more sense.
- 4
Fix it and verify
We make the repair, test the system, and make sure it's running the way it should.
Signs you need a repair
Most breakdowns give some warning first. Calling early usually means a smaller, less expensive fix.
- No heat, no cooling, or no hot water
- Air from the vents that's lukewarm or the wrong temperature
- A system that turns on and off every few minutes
- Ice on a heat pump, AC coil, or refrigerant line that doesn't clear
- Water leaking around the furnace, indoor unit, or water heater
- New banging, grinding, squealing, or buzzing noises
- A burning smell, or bills that jump for no clear reason
Quick checks before you call
A few simple checks can save you a service call. If none of these fix it, call us at (707) 988-5858.
- Make sure the thermostat is set to heat or cool and has fresh batteries
- Check the breaker for the system or water heater
- Replace a dirty air filter
- Clear leaves and debris from around the outdoor unit
- For a gas water heater, check that the pilot or burner is lit
Safety first
If you smell gas, don't use switches or flames. Leave the house and call PG&E or 911 from outside. If you see scorch marks, smell burning, or a breaker keeps tripping, turn the system off and call us.
Repair or replace?
We'll always tell you whether a repair makes sense. As a rule of thumb, repairs are usually worth it on newer equipment. Replacement is worth a look when a system is near the end of its typical lifespan, needs a major part like a compressor or heat exchanger, or keeps breaking down. We'll price both options so you can decide, and if you choose to replace, we can usually apply what we learned during the repair visit to the new design.
Typical lifespan and when to consider replacing
| System | Typical lifespan | Consider replacing when |
|---|---|---|
| Heat pump | 12 to 15 years | It needs a compressor or major repair past about 10 years |
| Air conditioner | 12 to 15 years | It needs a major repair and your furnace is aging too |
| Gas furnace | 15 to 20 years | It has a cracked heat exchanger or keeps failing |
| Ductless mini split | 12 to 20 years | Repairs are frequent or parts are hard to get |
| Gas or electric tank water heater | 8 to 12 years | The tank itself is leaking |
| Tankless water heater | 15 to 20 years | The heat exchanger fails on an older unit |
| Heat pump water heater | 10 to 15 years | The compressor or sealed system fails out of warranty |
Our work
Recent projects in Sonoma and Marin
Real Green Core jobs for homeowners in Sonoma and Marin, with photos from the job site.
August 2026
AC repair and refrigerant service in Santa Rosa
We diagnosed the system with digital gauges, sealed leaking refrigerant line joints, and verified electrical connections to restore steady cooling.
See the job photosJuly 2026
Furnace and AC tune-up with duct repair in Sonoma
We serviced an American Standard furnace and outdoor unit, tested the electrical components, cleaned the condenser coil, and replaced damaged duct sections.
See the job photosJuly 2026
HVAC maintenance and electrical diagnostics in Rohnert Park
We inspected the outdoor unit, attic air handler, and furnace, tested capacitors, contactors, and controls, checked refrigerant pressures, and cleared the condensate drain.
See the job photos
HVAC & Water Heater Repair across Sonoma and Marin
- Petaluma
- Rohnert Park
- Santa Rosa
- Novato
- San Rafael
- Mill Valley
- Tiburon
- Sebastopol
- Cotati
- Windsor
- Sonoma
- San Anselmo
- Fairfax
Also see: Installation & Replacement · Maintenance & Tune-Ups
FAQ
Frequently asked questions
How fast can you come out for a repair?
For urgent calls we aim to respond same-day or next-day, depending on the season. Call (707) 988-5858 and we'll give you an honest timeline.
Should I repair or replace my system?
It depends on the system's age, condition, and the cost of the repair. If a heat pump, AC, or furnace is past about 12 to 15 years old and needs a major repair, replacement is often the better investment. We'll lay out both options so you can decide.
Do you repair all brands?
We work on most major brands of heat pumps, air conditioners, furnaces, ductless mini splits, and water heaters.
Do you repair water heaters?
Yes, including heat pump, tankless, gas, and electric water heaters. If replacement is the better call, gas and electric tank installs start at $2,850, with same-day replacement when our schedule allows.
What should I do if I smell gas?
Don't use light switches, appliances, or flames. Leave the house right away and call PG&E or 911 from outside. Once the gas utility has made it safe, we can repair the appliance.
Why is my water heater leaking?
A leak from a valve or fitting can often be repaired. A leak from the tank itself means the tank has failed and needs to be replaced. Turn off the water supply and power or gas to the heater and call us.
Do you repair systems in Petaluma, Santa Rosa, and Marin?
Yes. We repair heating, cooling, and water heaters in Petaluma, Santa Rosa, Rohnert Park, Cotati, Sonoma, Windsor, Sebastopol, Novato, San Rafael, Mill Valley, San Anselmo, Fairfax, and Corte Madera.
Ready for comfort that just works?
Tell us a little about your home and we'll get back quickly with clear options — no hard sell.