Why Does My Car Warm Up So Slowly?
[BSD] This is a symptom of a bad thermostat. A properly functioning thermostat will almost totally block water flow through the engine and heads. That water will heat up quickly, even at idle, especially when it is around 50 degrees outside. If you drive you car, it will warm up more quickly. This failure seems to be fairly common. .
When that water gets hot, the thermostat opens up and lets cool(er) water flow in and allows the now hot water to flow out and cool down. Your heater begins to work at this time. That time should be in just a few minutes, especially if you are driving the vehicle during this time.
A thermostat which is stuck open will exhibit a few symptoms.
The "running" or "warm" temperature will fluctuate with outside temperatures or with how spirited the car is being driven.
[CL - 99/11/5] The interstate is about 1 mile from my house. The engine is warm by the time I get on it and up to normal warmth about 1/2 mile after that.