The roof, the roof, the roof is…freezing. You need to fix your heater.
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As summer comes into view, you'll likely notice that most drivers aren’t too worried about their car’s heater. It worked this last year, and the year before that, why wouldn’t it work this year? Well, fine drivers, life tends to throw curveballs at you, and guess what, your heater isn’t working properly anymore. Ha!
But don't worry, heaters aren’t the mysterious beast most make them out to be. Heating systems consist of a heater core, a heater fan, the car’s coolant system, and your HVAC controls. As hot coolant is drawn into the heater core, the heater fan, controlled by the HVAC controls, blows that heat into the cabin as the cooled coolant returns back to the system. Though a simple system, a number of issues can arise causing your heating system to not function properly.
And now is the perfect time to learn what can go wrong and decipher if your car’s heater is kaput. Follow along as The Drive’s whip-smart info team breaks down the top reasons why your car heater isn’t working properly and how to fix them.
As with any faulty object, any of a host of reasons can prove to be the leading culprit. To better diagnose your car’s on-the-fritz heating system, let’s get into the reasons it can go bad.
A faulty or broken thermostat is the most common cause of your car’s failing heat. Stuck open or stuck closed, the part can not only cause issues with your heat but also with your engine’s cooling system. One becomes an issue of comfort, the other becomes an issue of “Oh no, I’ve borked my engine.”
The second-most common issue is low antifreeze or coolant. When your coolant/antifreeze levels drop, the hot fluid can’t make it to the heater core, and thus, your cabin remains chilly. This can occur if the engine is working too hard and overheats or if it wasn’t properly filled.
While you may be getting hot coolant/antifreeze into the heater core, the heater fan, the part that actually blows the heat into the cabin, can break or suffer an electrical short.
If the blower motor resistor is broken, you might have issues setting the fan speed or getting air at all.
Occurring less often than the above issues, debris and particulates that make it into the coolant system can clog your heater core. This can happen when a radiator rusts from the inside or if debris gets through the radiator and lodges itself into the heater core. Either way, you’re looking at refurbishing your heater core or straight-up replacing it.
A leaky radiator could prevent coolant from reaching your heater core and could damage your engine, at worst.
Simply put, your car’s buttons, knobs, or haptic feedback touchscreens may not be triggering the heating system. Shorts, broken dials, and bad touchscreens can all lead to malfunctions that prevent your heater from working.
Similar to your broken HVAC controls, your car’s wiring could be broken or have a short in it. This would mean the heater isn’t triggered when the driver commands it to function. Not good.
To assuage your fix-it fears and show you just how easy DIY repairs can be, The Drive put together an easy-to-follow guide on how to fix a broken thermostat. You will need to purchase new coolant and a new thermostat.
Working on your car can be dangerous and messy, so here’s exactly what you’ll need to ensure you don’t die, get maimed, or lose a finger and that you keep your jeans, shirt, and skin spotless—hopefully.
We’re not psychic, nor are we snooping through your toolbox or garage, so here’s exactly what you’ll need to get the job done.
The second-most common culprit is that your car has low antifreeze or coolant. Thankfully, it’s far less time-consuming than replacing your thermostat. All you’ll need is a funnel and new coolant. Ready?
To borrow a phrase from the most excellent Archer, “Noooooooope!” We’re gonna need you to absolutely stop thinking about how you can heat your car without a heater. Why? Because you can’t. Any form of outside heat like a space heater, whether electric or propane, is a surefire way of setting yourself and your car on fire. And if you try to emulate some sketchy blog’s “Life Hack,” you’ll end up like this lad. And you don’t want to be this lad. He’s a bad role model.
The common thinking is every five years or 100,000 miles. Yet, that could change if you’re having issues with your heat or your car overheating.
We're visual learners, so we figured we'd give you this handy-dandy video of diagnosing your car's heater issues from our friends at O'Reilly. Check it out!
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