Frequently Asked Questions

Size is determined by a Manual J load calculation, not square footage alone. Your home's ceiling height, window orientation, insulation, and LA climate zone all affect the result. A system sized only by square feet is often 20-30% oversized. Oversized AC short-cycles, leaves humidity in the air, and wears out faster than a correctly sized unit.

Installed cost for a central split system in Los Angeles typically ranges from $5,500 to $14,000, depending on system size, efficiency tier, electrical work required, and permit fees. Ductwork installation adds cost if the home has none. Every Mister Cool California estimate is itemized by line: equipment, labor, permit, and any duct work listed separately.

Most residential AC installations take one to two days on-site. Permit approval from LADBS adds time before work begins, typically three to ten business days. Homes requiring new ductwork add one to three additional days. The full timeline from first call to final inspection runs two to four weeks in most cases.

Yes. The Los Angeles Department of Building and Safety requires a mechanical permit for all central AC installations. Mister Cool California pulls the permit under C-20 license #1143117. The homeowner does not need to file anything separately. A city inspection closes the permit after installation is complete. See Los Angeles HVAC permits.

Central AC can be installed in homes without existing ductwork. The process includes duct design using Manual D calculations, fabrication of duct runs, and Title 24 compliance verification. In some older Los Angeles homes, particularly bungalows with no attic access, a ductless mini-split system may be the more practical solution. A site assessment determines which option fits the structure.

All systems Mister Cool California installs meet California Title 24 standards. New AC equipment must meet minimum SEER2 thresholds set by the California Energy Commission. Duct leakage testing and HERS verification are coordinated as part of the installation when required. HERS is a third-party inspection, separate from the city building inspection, and is scheduled before the permit closes. More on Title 24 compliance.

AC replacement means removing an existing system and installing a new one in its place. Installation refers to putting in a system where none existed before. These are distinct projects with different scopes and permits. One quote covers whichever applies to your situation, you do not need to request both.

Central AC replacement in Los Angeles typically runs $5,000 to $13,000 installed. That range includes equipment, labor, and the LADBS mechanical permit. Title 24 duct leakage testing adds cost if existing ducts fail the threshold. Duct repairs or sealing, if required, are quoted separately on the written estimate before any work begins. See the AC replacement cost page.

A system that turns on but uses R-22 refrigerant cannot be recharged with new refrigerant. R-22 production ended in 2020. Only recovered stock is available, at sharply elevated cost. When the repair estimate for an R-22 system exceeds 50% of replacement cost, replacement typically makes more financial sense, and Mister Cool California will show you both numbers in writing before you decide.

Most AC replacements take one day on-site for equipment swap. Permit approval from LADBS runs three to ten business days before work can begin. HERS verification, required when ductwork is involved, adds one additional scheduled visit after installation. Total time from first call to closed permit is typically two to three weeks.

The existing unit may have been the wrong size from the start. Many Los Angeles homes were installed with oversized systems in the 1990s and early 2000s. Replacing with the same tonnage repeats the original error. A Manual J calculation confirms the correct size for the home as it exists today, not as it was originally permitted. See load calculations.

The surety bond, Bond #7901206616 through Nationwide Mutual Insurance, provides financial recourse if a contractor causes damage or fails to complete agreed-upon work. It is not the same as general liability insurance. The bond is a legally required financial guarantee held by the California Contractors State License Board. You can verify it directly through CSLB.

If your question is not here, call the crew and ask directly. (323) 770-7737

Most common AC repairs, capacitor replacement, contactor swap, or condensate drain clearing, are completed in one to three hours. Refrigerant leak detection and recharge takes two to four hours depending on leak location. Coil replacements or compressor work require a return visit with ordered parts. The technician confirms the timeline after diagnosis.

Four causes account for most warm-air complaints: low refrigerant from a leak, a failed run capacitor stopping the compressor under load, a frozen evaporator coil blocking airflow, or a dirty condenser coil preventing heat rejection outdoors. A technician checks refrigerant pressure, capacitor readings, coil condition, and airflow in sequence before identifying the cause. More on an AC that is not cooling.

No parts are ordered or installed without the homeowner's written approval. Mister Cool California technicians complete the diagnostic first. They deliver a written finding, component checked, condition measured, repair recommended, before any part is sourced. Nothing proceeds past diagnosis until you review the findings and agree to the specific repair.

Wildfire smoke contains PM2.5 particles, particles smaller than 2.5 microns. These particles pass through standard one-inch furnace filters. They accumulate directly on the evaporator coil surface during smoke events. A coil coated with smoke particulate restricts airflow and recirculates contaminants every time the system runs. Los Angeles's fire seasons make coil fouling a real, recurring problem, not a theoretical one. See wildfire smoke and your HVAC.

Technicians follow a fixed diagnostic sequence, refrigerant pressure, capacitor function, coil condition, thermostat calibration, and airflow, before drawing any conclusion. No step is skipped based on what the technician thinks is most likely. The homeowner receives a written finding before any repair begins. C-20 license #1143117 covers all refrigerant circuit work legally in California.

Cooling capacity for window units is measured in BTUs per hour. A 100-square-foot room needs roughly 5,000 BTUs. A 300-square-foot room needs 8,000-10,000 BTUs. Rooms with west-facing windows or significant sun exposure need 10-15% more capacity than the base calculation. An oversized unit short-cycles and leaves the room feeling damp rather than comfortable.

If your question is not here, call the crew and ask directly. (323) 770-7737

Yes, but a standard window AC will not fit a casement window. Casement windows are crank-operated and open outward, they require a vertical-format casement AC unit designed for that window type. These units are less common than standard window ACs. A technician confirms which unit fits the window dimensions before installation day.

A standard window unit installation takes 30 to 90 minutes, depending on window access and whether bracket mounting is required. Installations that involve electrical circuit verification, checking amperage draw against the existing circuit, add 20 to 30 minutes. Casement window installs take slightly longer due to the vertical mounting configuration.

Most window AC installations in Los Angeles do not require a permit. However, if the installation involves adding or upgrading a dedicated electrical circuit, an electrical permit is required through LADBS. Installing a unit on an existing circuit with verified capacity does not trigger permit requirements. A technician confirms the circuit situation before installation begins.

Mister Cool California technicians check the circuit's startup amperage draw, not just the running draw, before mounting any unit. Startup draw can be two to three times higher than the amperage listed on the box. This single check prevents the most common cause of window AC failure in the first summer. Work is performed by C-20 licensed crews, not general handymen.

If your question is not here, call the crew and ask directly. (323) 770-7737

Leak detection is included in the recharge service at Mister Cool California, not priced separately. Adding refrigerant to a leaking system without finding the source is a temporary fix that fails within months. Every recharge visit includes an electronic leak search first. If no leak is found, the system is recharged. If a leak is found, the repair is quoted before refrigerant is added.

A complete visit, leak detection sweep plus recharge, takes two to four hours. Leak detection using an electronic detector at coils, line set connections, and Schrader valves takes 30 to 60 minutes before any refrigerant is added. Subcooling and superheat measurements confirm correct charge at the end of the visit. Leak repairs add time depending on location and access.

Refrigerant in a sealed system does not get used up. If it was low last year and is low again now, there is an active leak. Topping off without finding the leak lets the leak continue. The compressor runs with insufficient refrigerant pressure again within months. Repeated recharges without leak detection also violate EPA Section 608 regulations for systems above 50 lbs of refrigerant.

R-22 systems can still be recharged, but only with recovered and recycled R-22, not newly manufactured refrigerant. R-22 production and import ended January 1, 2020. Recovered stock is available at significantly higher cost than it was five years ago. For systems with large leaks, the recharge cost often approaches or exceeds the cost of replacing the system with a new R-454B unit.

EPA Section 608 certification is required for any technician who purchases, handles, or recovers refrigerants. This federal certification applies to all refrigerant types: R-22, R-410A, and R-454B. Refrigerant work performed by an uncertified technician violates federal law. Mister Cool California operates under C-20 license #1143117.