How To Check If A Heater Core Is Bad

How To Check If A Heater Core Is Bad

One of the routine checks to perform on your car involves the heater matrix. Here are the basics on how to detect heating problems in your car and when to take it to your local service center for a fix.

Right, we're now going to try and diagnose a heating problem with inside the car. We suspected the heater matrix. Now, we go through a series of tests to bring us to that conclusion.

Starting with, we should always check the expansion bottle here to make sure the level is correct with water in there which is if the level is low, it will make the heat be cold. So once we've checked that by removing the cap and looking at the indicators on the side which are quite difficult to see sometimes, but quite often by trying to move the bottle a bit, you could actually see where the water level is in there. If that's showing fine, then we would move around and we would look for any visible leaks around the engine that we could see and any visible water leaks.

So, we check the radiator to the best of our ability which is situated here, which isn't particularly easy on most cars nowadays, but you would see puddles of water on the floor. We then move around and we check the hoses to make sure there's no leaks from the hoses, again no visible signs of leaks anywhere that will explain why the water is going down perhaps or why the heater's cold. We would then move to the heater pipes which, in this model, are these two pipes situated here and they basically go down behind the engine and marry up with the heater matrix which is inside the vehicle, inside the heating box, which is basically a much smaller version of the radiator in the front of the car.

And one of the only ways to test this, really, is to either flush this with water, so you basically connect a water supply to this hose, remove this hose connected to there, so you're going towards the vehicle with the water, remove this hose and the water should flow out of this hose. If that doesn't, that would indicate that you've got a blocked heater matrix. Or a quicker test is once the engine's being run, switch the engine off once the engine's at temperature and if you feel these hoses very carefully because they may be hot, you'll find one may be hot and the other one should be hot.

If that's the case, that's showing you the heater matrix is flowing kind. If you've got one that's cold and one that's hot, that's showing you there's no flow of water through the heater matrix. In that case, you then need to consult your local garage or main dealer.