How To Maintain Your Car’s Heater

If you have kids, you have probably watched the Frozen movie a thousand times, but what’s worse is being in it. As winter approaches and the mercury drops lower and lower, we rely heavily on our cars to keep us warm on the road. But imagine driving your car with a poorly functioning or broken heater. It is pretty much like sitting in your freezer in the middle of the road. Don’t make your car the studio for the next Frozen movie, fix your car’s heating system before winter sets in.

The heater is actually part of the engine’s cooling system and so any issues with the cooling system will directly affect the performance of the heater. Hence most of the causes of heater failure are directly connected to cooling system problems. 

Hot engine coolant runs from the engine to the heater core (which is essentially another small radiator situated in the cabin behind the firewall) through pipes. If the coolant level is low in the system, the hot coolant may not reach the heater core which restricts the hot air supply in the cabin. With the engine cold, open the radiator cap and check the coolant level making sure it reaches the spout. If not, then top it off to the required level. Now check the coolant reservoir and fill it to the cold fill level indicated on the reservoir sides. 

The job of the thermostat is to regulate the engine temperature, making sure cold coolant from the radiator is only allowed when the engine reaches operating temps. If the thermostat fails and stays open, the engine does not reach operating temperature causing cold coolant to run through the heater core. This will result in the heater not working in the cabin and can also cause the engine to idle rough and consume more fuel.  You will need to replace your thermostat to fix this issue.

The heater core can also be at fault causing the heating to not work in the cabin. Bad or contaminated coolant can cause the heater core to develop rust over time leading to a leak. This may also cause a clog in the heater core passageways which will restrict hot coolant flow through it and the cabin will either not receive warm air or get very little heating. A leaking heater core will result in a pool of coolant spilled in the passenger or driver’s footwell or a strong odour coming from the dashboard. If your heater core is leaking then the best solution is to have it replaced. However, heater core replacement is very complicated as it requires the disassembly of the entire dashboard to reach the heater. This is why it is important to rule out all other issues before having your heater core replaced by a professional. Flushing the cooling system can help rid the clog within the heater core without having to completely replace it. Here’s how you can carry out a complete coolant flush making sure the heater control valve is open.

The heater core only receives hot coolant when the heater control valve opens and allows coolant flow. If the heater control valve is broken, the coolant passage is stopped. To check if the heater control valve is working in your car, cycle between the on and off switch on the HVAC controls with the heater on and observe if the valve moves at all. If not then you will have to replace it. During an emergency, you can bypass the control valve manually in case of mechanical and vacuum valves. Some cars do not have a heater control valve at all so if you can not find one then you most likely don’t have it.