When your heating or air conditioning fails in Los Angeles

1. If you smell gas, touch no switches, phones or anything electrical. Leave, and from outside call SoCalGas at 1-800-427-2200 or 911. Do not try to stop the leak or turn the gas back on yourself; SoCalGas does that.
2. If a carbon monoxide alarm sounds, or anyone has a headache, dizziness or nausea while the heat runs, everyone goes outside. Call 911 from outside. Stay out until told it is safe, and do not run the furnace until a qualified professional has inspected it.
3. Find the electrical panel, a gray metal box of switches called breakers, in the garage, a closet or on an outside wall. Open it only if the floor there is dry. If a breaker is warm, discolored or smells burnt, call an electrician instead. Otherwise push the tripped breaker, the one sitting between on and off, fully off, then on, once. If it trips again, leave it off; repeated resets can start a fire.
4. Look for ice on the copper pipes at the outdoor or indoor unit. If you see any, set the thermostat to off and its fan to on, and let it melt. Running a frozen system can destroy the compressor, the pump that drives it.
5. Never heat the house with the oven, and never run a generator, burn charcoal or use a camp stove indoors or in the garage; they make carbon monoxide. A generator stays more than 20 feet from any window, door or vent.
6. Before anything is moved or repaired, photograph the equipment, the damage and the model plate, and write down the date.
7. Check the thermostat. If the screen is blank, replace its batteries. Set it to heat or cool, a few degrees past the room temperature.
8. Check the two power switches. The light switch on or beside the furnace should be on. In the small metal box by the outdoor unit, the lever should be on or the pull-out block pushed fully in.
9. Check the air filter, in a slot where the big return duct meets the furnace or indoor unit, or behind the large wall or ceiling grille. If no light passes through it, replace it; a clogged filter can freeze the indoor unit or overheat a furnace.

For a gas smell or a carbon monoxide alarm, SoCalGas or 911 first, from outside.

If you hold a home warranty, call that company before anyone touches the equipment; the contract decides who does the work.

For the equipment, call a contractor whose license carries the C-20 classification, the heating and air conditioning category of the Contractors State License Board (CSLB). At cslb.ca.gov you can list licensed contractors by city or zip code. Any technician who handles the refrigerant, the gas inside the copper pipes, must hold the EPA's refrigerant technician certification. Replacing the electrical panel with a larger one is C-10 electrical contractor work. The heating contractor may run a new circuit only when it is a necessary part of the job; otherwise that is C-10 work too.

Call your insurer only when a covered event, such as fire or lightning, caused the failure.

At cslb.ca.gov, open Check a License and search by license number, business name or personnel name.

Status says whether the license is current and active, suspended or expired. Classifications should include C-20. The record lists the bond, a guarantee that pays customer claims up to a set amount, and workers' compensation. A C-20 record should show no workers' compensation exemption, the sworn statement that a contractor has no employees. California requires heating and cooling contractors to carry the insurance even with no employees. Complaint disclosure shows citations, legal actions and unpaid arbitration awards, but the law limits what CSLB may show, so an empty section proves nothing.

Ask to see the pocket license, the wallet card CSLB issues, and a photo ID, and compare both with the record.

Get in writing before work starts:

• The diagnosis: what failed and why.
• A contract with the license number, business address, the work and materials, price, approximate dates and any down payment.
• A certificate of liability insurance, proof the company is insured for damage it causes.
• Who applies for the permit, and whether the ECC-Rater field test, explained below, is included.
• The parts and labor warranties.

Red flags, most from CSLB's list:

• A license number that belongs to someone else.
• Demands for cash, or a deposit above $1,000 or 10 percent of the price, whichever is less.
• Pressure to decide today, a door-to-door offer, or no written contract.
• A free inspection that finds an emergency, or a bid far below the others.

If a technician condemns the furnace, ask for a photo or the test readings and a second opinion; SoCalGas checks gas appliances on request at 1-800-427-2200.

These steps apply when a covered event, such as fire or lightning, damaged the equipment. Read your policy's covered events and exclusions first.

1. Report it promptly, stating the event and date. Get the contractor's written diagnosis, and keep the failed parts until the adjuster, the person the insurer sends to inspect the loss, has seen them.
2. Prevent further damage, and keep every receipt; your policy requires it. The California Department of Insurance says the insurer reimburses reasonable protection costs when you keep receipts, and that a policy may not cover damage that follows if you did not.
3. At the adjuster visit, ask for the scope of loss, the written list of what is damaged. Ask whether you are paid replacement cost, the repair cost with no deduction for depreciation, or actual cash value, which deducts for age and wear.
4. You choose the contractor. Under California's insurance regulations, an insurer may not steer you to a company unless you asked for a referral or it told you in writing that the choice is yours.
5. If the claim stalls, write to the claims manager and the claims executive at the company's headquarters. Then call the California Department of Insurance at 1-800-927-4357 or file a Request for Assistance at insurance.ca.gov.

Diagnosis and sizing first. A replacement is sized from a Manual J load calculation, the room-by-room math for what your house needs, not from the old unit's label. An oversized system can short-cycle, running in short bursts, and cool unevenly.

Equipment by model number: outdoor unit, indoor unit (the coil or air handler), furnace, thermostat. Efficiency is rated as SEER2 and EER2 for cooling and HSPF2 for heat pump heating; higher is better. The yellow EnergyGuide label on the outdoor unit shows SEER2.

Refrigerant. Under EPA rules, new air conditioners and heat pumps made from 2025 use lower-impact refrigerants. A system made entirely before 2025 can still be installed, and existing systems can still be repaired. Ask which refrigerant is quoted.

Permit and field test. The quote names the mechanical permit, the ECC-Rater field test explained below, and who pays for each.

Payment, changes and cancellation. The deposit cannot exceed $1,000 or 10 percent of the price, whichever is less, and payments cannot run ahead of the work. Any change needs a written change order signed before the work. Under California law, a contract signed at your home can be canceled in writing or by email within three business days of receiving a signed copy. That is five business days if you are 65 or older, and seven for declared disaster repairs. A true emergency service and repair contract is different: $750 or less, for work you asked for, nothing sold beyond the fix, and nothing due until the job is done. Its cancellation right ends once you hold a signed copy and work begins. If the contract does not meet those limits, the full cancellation rights apply.

Warranties and rebates. Get in writing the parts and labor warranties, who registers the equipment, and who files any rebate and what happens if it is denied.

Older homes. In a home built before about 1980, and sometimes later, plaster, acoustic ceilings, floor tile and the insulation on pipes and furnaces can contain asbestos. Paint from before 1978 can be lead paint. Only a lab test can tell. The South Coast Air Quality Management District requires an asbestos survey before most renovation or demolition by a contractor, whatever the home's age; removal is a separately licensed trade. A firm paid to disturb pre-1978 paint beyond a small patch must hold EPA certification for lead paint work. Untested paint is treated as lead paint.

• What is your license number, and does C-20 appear on it?
• Who did the load calculation, and can I have the report?
• Who applies for the permit, and is the ECC-Rater field test included?
• Does my electrical panel have capacity for this system, and if not, who does the electrical work?