Concord AC repair in Sunnyvale, Santa Clara and Cupertino usually comes down to a few parts that wear out on any air conditioner: the capacitor, the contactor, the fan motor, a dirty coil. Furnace and heat pump calls follow the same logic, with one failed component behind the symptom. We service Concord central air conditioners, heat pumps and furnaces. If you came here asking who makes Concord: it is a brand of Lennox International, so the Lennox page is related reading.
Read the Concord data plate first
Every Concord unit carries a metal or foil label with the facts a repair depends on. On the outdoor unit it is on a side panel; on a furnace it is inside the blower compartment door.
- Model number. Identifies the equipment type and capacity, and it is how parts are matched.
- Serial number. It usually encodes the build date, which is the quickest way to learn the system’s age.
- Refrigerant type. An R-22 system is hard to keep recharged, because R-22 is no longer produced in the US.
- Electrical ratings. The minimum circuit ampacity and the maximum breaker size show whether the circuit feeding the unit is right.
A clear phone photo of each label, outdoor and indoor, saves time on the call.
Concord AC problems and what usually fixes them
| What happens | Typical cause | Usual repair path |
|---|---|---|
| Outdoor unit hums, nothing spins | Weak start or run capacitor | Test it under load and replace it |
| Unit clicks on and off every few minutes | Worn contactor, a thermostat fault or an overheating compressor | Contactor and control voltage readings first |
| Indoor blower silent, outdoor unit running | Blower motor, its capacitor, or the control board | Motor and board tests at the furnace or air handler |
| Frost on the big copper line outside | Restricted airflow or low charge | Thaw, check filter and coil, then refrigerant readings |
| AC trips the breaker at start-up | A compressor shorting out, or damaged wiring | Insulation and winding tests before anyone resets it again |
| Warm air on the hottest afternoons only | Dirty outdoor coil or a condenser baking in full sun | Coil cleaning and a look at the airflow around the unit |
The full checklist is on our AC repair page.
Concord furnaces and heat pumps
A Concord gas furnace that will not light is checked step by step: thermostat demand, the inducer and pressure switch, the igniter, the flame sensor, the safety switches and the blower. On a Concord heat pump the winter checks center on the defrost sequence, the reversing valve and the backup heat. A part that fails once is a repair. The same part failing every season points to a cause upstream, such as poor airflow, and repeated failures are also a reason to start comparing repair with replacement. See furnace repair and heat pump repair.
When repair still pays on an older Concord
Repair usually makes sense when the failed part is minor and the system has kept the house comfortable. The picture changes with:
- a failed compressor or a cracked heat exchanger on an older unit
- an R-22 system with a refrigerant leak
- several repairs in the last few seasons
- rooms that never cooled or heated evenly, even when the system worked
We show you both paths with the cost factors for each before any work begins. If replacement wins, the quote lists equipment, labor, permits and optional upgrades separately; see new installation and AC installation.
Urgent Concord problems
Some failures should not wait for a convenient day: no cooling during a heat spell, no heat on a cold night, a breaker that keeps tripping, water spreading from the indoor unit, or buzzing and a burning smell. Switch the system off at the thermostat, and at the breaker too if anything smells hot. Our phones are answered 24/7, technicians work 8 AM to 8 PM every day, and the urgent visit starts with electrical safety checks. More on emergency service.
Concord service and maintenance
A yearly visit, the AC side in spring and the furnace side in the fall, covers filter and airflow, coil condition, electrical parts, the condensate drain and thermostat behavior, and notes any part that is starting to wear. Repairs are backed by a warranty covering parts and labor, and our EPA-certified technicians handle refrigerant work.