Google Home is adding a practical layer of protection for homes that rely on central cooling. With version 4.20, the platform can now detect when an AC system connected to a Google Nest Thermostat is no longer cooling properly and alert users before indoor temperatures climb too far.
The most useful part of the update is the early warning. When the system senses that the air conditioner is not doing its job, users can receive a notification saying the AC is not cooling and that there may be a compressor problem.
Google said that alert can appear in several places at once, including the Nest Thermostat itself, the Google Home app, and device notifications. That wider delivery matters because a cooling failure often becomes urgent quickly during extreme heat.
What can trigger the alert
The compressor sits at the center of the cooling process, so failures there can stop cooling altogether. Google says several conditions may trigger the warning, including an automatic lockout meant to prevent overheating or mechanical damage, failed parts such as the compressor motor and starter capacitor, and incorrect wiring configurations.
That means the system is not looking for only one type of fault. Instead, it is designed to recognize signs that point toward compressor trouble or related cooling issues, then warn the user before the problem gets worse.
A faster path to help
Google Home 4.20 also adds a more direct way to reach support. From the alert screen, users can contact a certified installer by phone or email with a single tap, provided the Nest Thermostat was installed by a certified professional and the contact details are already stored in the system.
Google also gives users a way to check whether that information exists. On the Nest Thermostat, they can press the ring, open Settings, and then go to Nest Pro to view the available contact details.
If no installer information has been saved yet, it can still be added later. Google says this can be done by asking the Nest Pro to enter their Nest Pro ID into the system.
That contact shortcut makes the alert more useful in real-world use. Instead of receiving a warning and then searching for a technician manually, users can move straight to the person who installed the system.
It also works for heating
The update is not limited to summer cooling. Google says the compressor warning and Nest Pro access also apply when the Nest Thermostat is set to heating mode.
In that case, the system can alert users if a heat pump fails to warm the room. The message will say that the heat pump is not heating and that there is a compressor problem.
This broadens the value of the feature beyond air conditioning alone. It turns the thermostat into a year-round monitor for HVAC issues, with a focus on identifying early signs of failure before the home becomes uncomfortable.
Availability and device limits
Google says the Google Home 4.20 update is rolling out now. That means the new features will arrive gradually for eligible users rather than all at once.
Support is not universal across older hardware, however. Google says the feature is not available on the first two Nest Thermostat models.
For households already using a Google Nest Thermostat with central air conditioning, the update adds an extra safeguard when the system starts showing signs of trouble. It gives users earlier notice, clearer context, and a faster way to contact help before the house turns uncomfortably hot.
