Heating For Nissan AltimaNovember 1, 2010November 4, 20102002 Nissan Altima only gets heat when car reaches 40 miles per hour.Is it my thermastat, heater core or what? Keywords:No Heat 1 thought on “Heating For Nissan Altima” Freeautomechanic November 4, 2010 at 8:16 am First thing to check is the coolant level itself. If the coolant level is low, the system will not perform correctly. Once the level is confirmed good, you can let the engine run for a while and check the two heater hoses at the firewall connecting to the heater core. If both hoses are luke warm, you may have a thermostat that is stuck open and should be replaced. If both heater hoses are HOTT! then you may just have a HOT/COLD blend door actuator failing. In your case the most common reason would be low on coolant or the thermostat. Comments are closed.