Why withholding rent over AC is risky
Be very careful. Because AC is often not a required habitability item in California, withholding rent over broken AC is risky and may not be justified — unless the AC was part of your lease or the situation crosses into a genuine habitability or safety problem. Get legal advice first.
Rent-withholding and "repair and deduct" are meant for serious habitability problems, and broken AC often does not qualify on its own. Withholding rent when it is not justified can quickly lead to an eviction case, even if you felt you had a good reason.
If AC was provided in your lease, or extreme heat has become a real health hazard, the picture may be different — but this is exactly the kind of situation to run past an attorney before you stop paying anything. Before withholding rent over broken AC, a free review can help you understand whether it is justified.
This is general information about California tenant rights, not legal advice. Every situation is different.