No heat in the winter or taking a long time for the car to warm up usually means the thermostat is stuck open. I took my thermostat out over the summer to keep the coolant flowing all the time as I was having overheating issues when autocrossing. When I put it back in around October, my car wouldn't be warmed up by the time I got to work and it's a 10 mile drive. Put the thermostat back in (before my head gasket replacement) and my car would be warmed up by the 1st street I got to (1/8th mile).