There’s No Heat in My Car!

We’re sure you’ve all experienced a moment when you climbed into your car on a cold morning, turned on the heat, and found you’re greeted with cold blowing air that never warms. Well, you’re not alone. We’ve all had a similar experience. We thought this might be a good time to educate you about where your automobile gets that warming heat from and what may be the problem. 

You might not believe it, but the warmth you feel on a cold winter’s morning comes from your automobiles cooling system. While this may sound like an oxymoron, it is actually the heat produced by your running engine. That heat is transferred into the engine coolant and then released via a “heater core” in the cabin of your car or truck. 

So what exactly is a heater core?

So what exactly is a heater core? The simple answer is “a mini radiator”. Just like the radiator in your engine compartment, you have a smaller radiator called a “heater core” that resides inside your instrument panel inside your car. Amongst all of the hoses that are under your hood, two of them are specifically dedicated to providing you heat, via the heater core, located inside your vehicle. Look closely under your hood and you will see two hoses, one into, and one out of your heater core. Now you cannot see the heater core as it is well hidden behind the instrument panel, but you can see the two hoses that connect to the firewall of the car. A firewall is the metal partition that separates the engine from the inside of your car. 

So what’s really happening with all this fancy equipment that causes me to have no heat? The answer is very simple. Hot water is created by your running engine and the automobiles water pump pushes water through all the hoses, including the heater core. The heater core warms up from the coolant. Then as you select “HEAT” on your dash, a door in the heater box is opened that encases the heater core. As you turn up your blower fan, air is drawn into the now open heater box, passes across the fan which forces air through the heater core. As the air exits the heater core, it has changed from cool to warm to hot air which is then forced out the vents thereby heating the interior of your vehicle. 

OK, great! But why no heat you ask? The most likely cause for no heat is a plugged heater core. A heater core gets plugged when contaminants in the coolant build up such that they block the tiny openings in the heater core and no longer allow coolant to pass through the core. Many of today’s vehicles are equipped with heat control valves which mechanically open and close to allow heated coolant to enter the heater core. During summer months or warm periods when we do not use the cars heat, in some cases for several months, the coolant sits stagnant in these closed off hoses and that’s a great place for rust, dirt and sediment to rest and build. The first cold day of the year when you command the heat “on”, all those contaminants rush toward the heater core and immediately block the inlet side of the heater core and “voila”, no heat. Of course, to limit this contamination buildup, it is recommended that you routinely have your cooling system flushed. 

Many of our customers have us “back-flush” their heater cores as colder weather sets in to avoid this very scenario. Back-flushing a heater core is quite simple and can be easily performed in 45 minutes or less, in most cases. Just beware that a coolant flush is very different from a back-flush. A coolant flush means to exchange out all the old coolant with new coolant. A back-flush means to disconnect the heater core hoses and force clean water backward against the normal flow of coolant to force and contaminants back out they same way they entered the heater core. Then the hoses are reconnected and the coolant system brought to operating temperature to verify the system is now producing heat and finally topping off the coolant system after riding of any air. In a back-flush, not all of the coolant is replaced. 

Back-flushing is always the preferred method for heater core related issues. In rare cases however, a back-flush simply cannot fix the problem, especially in those cases when corrosion has begun in the cooling system, due to lack of maintenance. In those cases, the only solution is to replace the heater core itself. This can be very expensive as, in most cases, the instrument panel must be removed and the heater box dis-assembled to replace the heater core. While the heater core is a relatively inexpensive item, the 7-10 hours labor to replace it is where your expense lies. Simple maintenance can prolong and possibly prevent this from occurring. 

Please stop by and allow us at Tierra Del Sol Automotive to evaluate your cooling system and advise you of any maintenance needed to keep your vehicle in tip-top operating condition. Scheduled maintenance is always cheaper than parts replacement and we want to help you keep your vehicle healthy and warm during cold spells.