Replacement · independent publisher, not a contractor
What happens during an AC replacement
An AC replacement runs from a home visit and written quote, through the permit, removal of the old unit and installation of the new one, to start-up, the Title 24 duct and refrigerant tests by a third-party rater, and the final inspection that closes the permit.
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More than a swap
Most guides describe a replacement as a crew arriving, pulling out the old unit and leaving by dinner. In Los Angeles that is only the middle of it. A legal replacement here starts with a permit and ends with two more visits: a third-party rater and a building inspector.
The steps in order
- Home visit. The contractor checks the existing system, ducts, electrical panel and where the equipment sits, and should run a load calculation.
- Written quote. Equipment, size, refrigerant, included work and exclusions. Compare quotes in the quote tool.
- Permit. The contractor applies to LADBS in the City of Los Angeles, or to your own city or county office. See the permit guide.
- Removal. Power is shut off, the old refrigerant is recovered (venting it is illegal), and the outdoor unit, coil and sometimes the furnace come out.
- Installation. New pad, outdoor unit, indoor coil or air handler, line set, electrical disconnect, condensate drain and thermostat.
- Start-up. The lines are pressure-tested and evacuated, the system is charged, and airflow and temperatures are checked.
- Title 24 tests. The California Energy Commission says replacing or altering an HVAC unit needs a permit, the contractor seals and tests the ducts, and a third-party rater verifies the work, including duct leakage.
- Final inspection. The building inspector signs off and the permit closes.
On installation day
| Phase | What you will see | What you may notice |
|---|---|---|
| Arrival | Truck, equipment, drop cloths | Driveway or street parking needed |
| Shut-down | Power off at the disconnect and breaker | AC off for the rest of the day |
| Recovery | Refrigerant pumped into recovery cylinders | Noise from the recovery machine |
| Removal | Old condenser and coil carried out | Attic or closet access opened |
| Set and connect | New pad and units, line set brazed, wiring | Brazing smell, attic foot traffic |
| Vacuum and charge | Gauges and vacuum pump on the lines | A quiet stretch while the vacuum holds |
| Start-up | System runs; technician takes readings | Cold air, then a walk-through |
The typical sequence of the trade, not a measured LA timetable. Ask your contractor for theirs.
The tests, in plain terms
Duct test
Under Title 24 Part 6, replacing the condensing unit, air handler or coil is an alteration that triggers duct sealing. Adding more than 25 feet of new duct means the whole system must test at 10 percent leakage or less.
Refrigerant charge checks apply to heat pumps everywhere and to ACs in zones 2 and 8–15.
Who checks it
From 1 January 2026 the CEC's Energy Code Compliance (ECC) program took over field verification from the HERS program, so the third-party rater on a 2026 change-out works under ECC.
If the ducts fail
They are sealed and retested. That is why a quote should say who pays if the ducts need work; duct repair is published at $800–$4,500 in LA. ENERGY STAR estimates 20 to 30 percent of air in a typical duct system is lost to leaks, so failing is common in older houses.
Things that turn a simple replacement into a bigger job
| Situation | Extra work | Published LA adder |
|---|---|---|
| Old ducts fail the leakage test | Seal, repair or replace ducts | $800–$4,500 repair; $3,500–$8,000 new |
| Heat pump replacing a gas furnace | New circuit; sometimes a panel | $2,000–$7,500 for 100 A to 200 A |
| Unit moved or longer refrigerant run | New line set | $300–$1,500 |
| Rooftop or hard-to-reach unit | Crane lift | $800–$2,000 |
| Asbestos on old duct wrap | Abatement by a licensed contractor | $2,000–$9,000 |
What you need to do
- Clear access to the outdoor unit, the attic or closet with the indoor unit, and the panel.
- Be home, or arrange access, for the rater's visit and the final inspection.
- Keep the finalled permit and test results. LADWP's heat pump rebate needs the final approved permit.
More on preparation: how to prepare your home. How long it takes: AC installation timeline.
Before the crew leaves
Your five-minute walk-through
- Ask to see the system running and the thermostat set up.
- Ask for the start-up readings in writing.
- Check the outdoor unit sits level on its pad with clearance around it.
- Ask when the rater and inspector are booked.
- Ask who registers the equipment warranty.
The full list is in what to check after installation.
Who is involved, and when
| Who | Role | When |
|---|---|---|
| The contractor (CSLB C-20) | Quotes, pulls the permit, installs, starts up | Visit, install day |
| The building office | Issues the permit, inspects | Before and after |
| Third-party rater (ECC) | Verifies duct leakage and refrigerant charge | After install |
| Your utility | Pays any heat pump rebate; may disconnect for a panel upgrade | After the final permit |
| HOA or landlord | Approves the outdoor-unit location | Before you sign |
How it differs by system
| Job | Extra steps |
|---|---|
| Heat pump replacing AC and furnace | Gas line capped, new circuit or panel, heat-mode check at start-up |
| Mini-split | Wall penetrations, a line set and drain per head, no duct test |
| New ducts | Old ducts removed, new ducts installed and sealed before start-up |
| Rooftop unit | Crane lift and roof work, often a separate day |
Red flags during the job
Stop and ask if you see these
- Work starting with no permit issued.
- Old refrigerant vented instead of recovered.
- Ducts left disconnected or unsealed in the attic.
- A different model from the one on the quote.
- No start-up readings, or no plan for the rater visit.
How payment usually works
CSLB cautions that a down payment should not exceed 10 percent of the contract price, and later payments should not run ahead of the work done or materials delivered. (CSLB)
| Stage | A sensible payment pattern |
|---|---|
| Signing | Down payment of 10 percent or less |
| Equipment delivered or installed | A progress payment for work done |
| Start-up | Most of the balance |
| Permit finalled | The last payment, after the inspector signs off |
An example pattern consistent with the CSLB guidance, not a legal requirement. Your contract sets the terms.
What the whole job costs
Add the adders your house needs, from the table above. Every source and date is on the cost guide.
Sources
- California Energy Commission, "Building Energy Efficiency Resources for Single Family Homes" (retrieved 2026-09-29)
- Energy Code Ace (CEC-supported), Single-Family Compliance Manual ch. 9, § 150.2(b)1E–F, 2022 code text; confirm against the 2025 code in force since 1 January 2026 (retrieved 2026-09-29) — verify before relying on it
- California Energy Commission, "Home Energy Rating System (HERS) Program" (retrieved 2026-09-29)
- LADWP, "Consumer Rebate Program" (retrieved 2026-10-20)
- LADBS, "Mechanical HVAC Permits" and Express Permits bulletin P/GI 2020-003 (LADBS refused our automated read) (retrieved 2026-09-29) — verify before relying on it
- ENERGY STAR, "Duct Sealing" (retrieved 2026-10-18)
- Reliable Heating and Air (Woodland Hills), AC installation cost in LA and Ventura County (retrieved 2026-09-29)
- Cold Cloud (Glendale), central air cost in Los Angeles (retrieved 2026-09-29)
- E & A Mechanical (Tujunga), heat pump installation cost in Los Angeles (retrieved 2026-09-29)
- HVACProjectCost.com, Los Angeles HVAC replacement cost (retrieved 2026-09-29)
Questions
What happens to my old AC unit?
The refrigerant is recovered by the technician, which federal rules require, and the old equipment is removed. Ask the quote to say that removal and disposal are included.
Do I need to be home during an AC replacement?
You need to let the crew in and be reachable. You or someone you trust should also be available for the rater's visit and the final inspection, which are booked separately.
Will my house be without power?
Only the AC circuit is usually off for most of the day. A panel upgrade can mean a longer outage arranged with the utility.
Is a third-party test required in Los Angeles?
Yes, on a permitted replacement. The CEC says a third-party rater verifies the installation, including duct leakage. Since 1 January 2026 those raters work under the ECC program.
What if my ducts fail the test?
They are sealed and retested before the permit can close. Duct repair is published at $800–$4,500 in LA, so ask the quote who pays if that happens.
Does the contractor get the permit?
They should, in their own name, under their CSLB license. Put "permit pulled by contractor" in the written quote.
Can the furnace stay when the AC is replaced?
Yes, if it is compatible with the new indoor coil and blower requirements. If it is also old, ask for a heat pump price that replaces both.
What paperwork should I get at the end?
The finalled permit, the Title 24 test results, the start-up readings, model and serial numbers, and the equipment and labor warranty terms.
How much does the permit add?
Two LA sources price the permit and Title 24 paperwork at $250–$800. It is a small line next to the equipment, and it should be in the quote.
Will the crew go into my attic?
Usually, if the indoor coil, air handler or ducts are there. Clear the hatch area and cover anything below it.
Next step
Free quote request
Get a quote to check against these numbers
- Tell us about the job. Service, ZIP, property and timing. The form says right away if your ZIP is outside the area.
- We check the license first. Requests go only to contractors whose CSLB C-20 license we have matched on the state register. If none covers your ZIP yet, we email you and say so.
- Compare what comes back. Line the written quote up against the published ranges and the quote checklist.
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