How to Fix the Heat in Your Car

There are cars that you just shouldn’t drive without some proper warm clothing — we call them convertibles. Not a soft-top owner? Then it’s entirely reasonable to assume that your car’s interior is habitable without the need for extra layers. Unfortunately, cars can break, and if yours has left you stranded without heat in a cold climate, you’re probably feeling highly motivated to fix it ASAP.

The cost and difficulty of your car’s heater fix will vary depending on exactly what is causing its frosty disposition. Quick fixes like adding coolant can be done at home for the cost of materials. If, however, you’ve got a broken heater core, plan on a visit to the mechanic unless you’re quite handy with a ratchet set.

Basic Issues and Quick Fixes

Let’s begin by checking a few basic items and move on to the big-ticket fixes later. The simplest fix for a cold car is adding coolant. Sounds counterintuitive, right? Your car relies on coolant to carry heat away from the engine. When you run your heater, you get some of that heat back in the form of air that’s been blown past the hot coolant.

Your car shouldn’t be completely out of coolant. If it is, make sure you add the proper amount back. If the coolant level is low, you might notice improved performance from your heater by restoring it to the stock level.

Similar to the coolant fix, you should also check on your car’s thermostat to see if it’s stuck open. Replacing a broken thermostat is something most weekend wrench-hands are able to pull off, and won’t cost an excessive amount.

In addition to these very common causes for lack of heat, you ought to inspect the heat control valve and HVAC doors on your car, which can break and keep warm air form reaching the cabin. Finally, observe the engine temperature of your car during driving to make sure there’s not an air bubble in your radiator, if there is, you’ll need to bleed your radiator to remove the trapped air.

More Advanced Heating Fixes              

If none of these seems to be the case, you could be dealing with the failure of a more major part. That doesn’t mean you can’t perform the fix yourself, but you may not have the mechanical knowledge to do it alone.

A possible culprit is your vehicle’s water pump. If it leaks, less coolant will move through your car’s water jacket, which has the same results we mentioned earlier. Look for an increase in your engine temperature and a coolant leak at the front of your car if you suspect your water pump is failing.

Finally, if none of these items appears to be the cause of your cold car, you may have a failed radiator or heater core. You should check these items every year as winter approaches, while performing other routine maintenance tasks like checking tire tread and running the AC for 10 minutes every 30 days in the winter months.

There are some very distinct sights and smells that can tip you off if your heater core is bad. Again, depending on how handy you are at DIY projects — and how partial you are to your car’s shiny unblemished dashboard — you might want to hand this one off.

Similar logic applies to the radiator, although if your radiator is severely compromised, you’ll know it because your car will quickly overheat during driving. You might even need to have it towed to a shop. Do not run your car for prolonged periods if engine temperature is in the red — you’ll have more than a radiator to pay for if you do.

So go forth and diagnose your heating problems with the knowledge that most of what can break isn’t all that difficult to fix. Before you get too carried away though, keep in mind that it’s always a good idea to have a spare hoodie or jacket stashed in the back seat, it may be the best value of any fix mentioned here.

Scott Huntington is a writer and car enthusiast from central Pennsylvania. Follow him on Twitter @SMHuntington or check out his blog, Off The Throttle.