Answers That Keep You Informed

Yes.

As of January 1, 2025, it is illegal in California to install newly manufactured HVAC equipment that uses R-410A refrigerant.

The only refrigerants legally allowed for new residential HVAC equipment are A2L refrigerants, specifically R-454B and R-32.
This regulation applies to new installations. Existing R-410A systems may continue operating but cannot be newly installed.

Because every new HVAC system installed from 2025 forward includes:

• A2L refrigerant

• Mandatory refrigerant leak detection sensors

• Safety mitigation logic built into the control system

These are life-safety systems, not comfort features.
If they are dirty, miswired, or unverified, the system may lock out without warning or fail to protect the home.

Yes.

While exact wording varies by brand, most HVAC manufacturers require or strongly recommend that A2L refrigerant leak detection and mitigation sensors be inspected, verified, and maintained every 6 months.

Manufacturers specify 6-month intervals because A2L sensors are:

• Continuously operating

• Sensitive to dust, debris, and contamination

• Dependent on correct wiring and communication

• Subject to sensor drift over time

Waiting 12 months significantly increases the risk of sensor failure, false shutdowns, or undetected safety issues.

Based on real-world field inspections, a large percentage of A2L sensors are not operating at all, even in brand-new systems.

In many cases, the sensor was:

• Never wired correctly

• Wired to the wrong terminals

• Installed physically but never verified to function

• Miswired due to manufacturer-specific requirements

The sensor may be present — but functionally useless.

Yes.

Based on field experience across multiple installations, it is estimated that up to 80% of A2L sensors inspected are not operating correctly at the time of first service.

This is not the homeowner’s fault.

It happens because:

• Every manufacturer has different wiring requirements

• There is no universal A2L wiring standard

• Many installers and technicians are still adapting to new A2L rules

• Functional testing is often skipped after installation

If an A2L sensor is wired incorrectly, it is essentially the same as not having one installed at all.

This can mean:

• Refrigerant leaks go undetected

• Safety mitigation never activates

• The system does not shut down when required

• The homeowner has a false sense of safety

In some cases, miswiring can also cause random shutdowns or nuisance lockouts.

Yes.

Many inspections verify:

• Physical installation

• Labeling

• Sensor location

They do not always verify functional communication between the sensor and the control board.

A sensor can pass inspection and still be:

• Miswired

• Disabled

• Nonfunctional

Only professional functional testing confirms the sensor actually works.

Because A2L systems are fundamentally different from older HVAC systems.

Homeowners should always verify that their technician is trained and certified in A2L refrigerant safety, including:

• Manufacturer-specific wiring requirements

• Leak detection and mitigation logic

• Safety shutdown verification

• Proper testing and documentation

Technicians without A2L safety training may:

• Wire sensors incorrectly

• Disable safety features unintentionally

• Miss nonfunctional sensors

• Create warranty and liability risks

Servicing an A2L system without proper training can result in:

• Disabled or nonfunctional safety sensors

• Incorrect wiring or configuration

• False shutdowns during extreme weather

• Voided manufacturer warranties

• Increased liability in the event of a failure

A2L systems should only be serviced by licensed, A2L-trained professionals.

Six-month maintenance allows trained technicians to:

✔ Verify correct wiring and sensor communication
✔ Catch installation errors early
✔ Clean sensors before contamination causes failure
✔ Prevent unexpected safety shutdowns
✔ Document compliance for manufacturer warranty protection

Waiting a full year greatly increases the risk of undetected safety failures.

No.

A2L sensors are life-safety devices and:

• Are manufacturer-specific

• Require technical documentation

• Must be serviced by licensed, A2L-trained HVAC professionals

Improper handling can disable safety protections or create serious risk.

A proper A2L maintenance visit includes:

✔ Verification the sensor is wired correctly
✔ Confirmation the sensor communicates with the control board
✔ Manufacturer-specific wiring validation
✔ Sensor cleaning and inspection
✔ Safety response testing
✔ Documentation for warranty and compliance

This goes far beyond a standard HVAC tune-up.