That's a pretty broad question did it work in Stealth mode ? Or ICE not that we really use any heaters in South Florida but I did notice it takes a fare amount of time to get heat . Not sure if you know but the car does have a small hot water heater it's located underneath the battery coolant tank which is the center coolant tank . Turn the heat on and feel the heater hoses going into the black rectangle unit under the coolant tank