(Illustration from the NYC Dept. of Housing Preservation and Development)
Landlords must provide heat to tenants from October 1st through May 31st each year under these conditions:
DAY: 6 AM to 10 PM - If the outside temperature is below 55° F, the inside temperature must be at least 68° F.
NIGHT: 10 PM to 6 AM - The inside temperature must be at least 62°F regardless of the outside temperature.
Measure the indoor temperature with a digital thermometer in the middle of your room. If the temperature on that thermometer is below the legal limit, file a 311 complaint. Then send the complaint number, including your name, apartment, and the time, date, and temperature to CPGTenAssoc at gmail dot com.