My Feet Are Cold!

The days are definitely getting cooler now. You may notice that your car’s heater won’t warm you up like it used to. Now that you want heat you notice that the air coming out of the floor vent is cool on your ankles.

The first item to check is the level of the engine coolant (anti-freeze) in the reservoir. A lack of heat is the first symptom that you will notice if your coolant level gradually goes down from a slow leak. A slow leak will usually not leave any drips on the ground. The leak only occurs when the engine is hot and under pressure, and the leak is slow enough that it is evaporated by the heat of the engine before it can form a drip. These slow leaks work over a period of weeks or even months, but eventually reach the point where the heater stops working. It is important to top off the fluid level because the next symptom after a loss of heat will be the engine overheating.

In the days long gone, if the coolant wasn’t low, it used to be a sure bet that your engine’s thermostat was stuck open. The thermostat is an old fashioned mechanical device that turns the flow of coolant between the engine and the radiator on and off. The thermostat could have begun to be stuck open any time last spring or summer and you would never notice because the engine just runs cooler. Engines still have thermostats, and they can still stick open, but with increased quality control the probability that the thermostat is the problem is much lower.

Most cars produced after 1996 use a damper behind the dash to blend hot air and cold air to reach your desired air temperature. In these vehicles there is heat from the heater core being produced summer and winter, and cold air produced by the air conditioner in the summer and fall. In the summer the damper selects only air conditioning. In the fall the damper blends some hot air and some cold air. On cold days the air conditioner does not come on at all and the damper blends hot air from the heater core with cool outside air.

A common problem on cars with a blend damper is a malfunction of the damper. Sometimes the electronic actuator that moves the damper fails. Other times the damper itself breaks. The damper and the case that holds it are made of plastic. With age and many years of constantly moving back and forth the damper eventually breaks.

Another problem that is primarily isolated to a few models of vehicles is a heater core that is plugged off from contamination. A few vehicles have a characteristic flaw that results in the cooling system getting “gunky”. If the cooling system is not flushed on schedule the heater core builds up with this gunk and stops producing heat. A flush to correct this problem is usually only a short term fix. Literally in the span of about a week the heater will again stop working. In these cases the only lasting correction is to replace the heater core. While this can occur on any car, the most prevalent cars are the Chevy Blazer, the Ford Taurus, and some Dodge trucks and minivans. All of these vehicles tend to be from the 1990’s and early 2000’s.

Brian Klaubert has written for the Neighborhood News since 2002, and owns Christian Brothers Automotive – Hamilton Mill on Braselton Hwy in Dacula. They have been voted Best of Gwinnett in both the Gwinnett Daily Post and Gwinnett Magazine.