Aftermarket July/August 2022 Issue

18 AFTERMARKET JULY/AUGUST 2022 TOP TECHNICIAN AND TOP GARAGE www.toptechnicianonline.co.uk BLOWING HOT AND COLD TPS’ twin-take on heating systems and coolants in modern vehicles, issues to look out for and why regular maintenance is essential A s professionals, it’s all too easy to assume that people understand how the heating system of their car works. It all makes perfect sense, right? If a problem occurs with a customer’s heating on a modern car though, then it’s a real problem. This is especially the case in the winter with frosty morning starts and dark cold drives home, but equally so in the middle of the summer when the heating just won’t stop. The diagnosis can often lead to more questions: “So, the problem is with my cooling system, not my heating?” Add in the air conditioning system and it can make for a confusing conversation. Blowing hot In its most basic terms, the heating system is a secondary cooling system. In a liquid-cooled vehicle, the heater fans blow air through a heater core/matrix and this core is part of the vehicle’s overall cooling circuit. Instead of being just another mechanism to keep the engine at its optimum running temperature, it takes that heat from the vehicles coolant and uses it to warm the cabin and its occupants. The flow of coolant is regulated by a heater control valve which controls how much hot air enters the cabin. However, in an internal combustion engine vehicle, that hot air doesn’t blow hot as soon as you start the car, unless fitted with a pre-heater or an EV, but let’s save that for another article. The colder the outside temperature the longer you’ll wait to feel the warmth and that’s because of the thermostat. A modern engine has an ideal operating temperature of between 90-105°C. When it dips below that temperature the vehicle is not running efficiently as the thermostat remains closed, keeping the coolant inside the engine and preventing it from travelling through the entire circuit. However, once the engine is hot enough the thermostat opens up and that hot coolant is allowed to the heater core, where you’ll start to feel it benefits. In vehicles with automatic climate control, sensors monitor the interior temperature of the vehicle and open once the coolant is allowed into the heating circuit. Blend doors and control flaps then open and close to maintain the selected temperature. Vehicles equipped with dual or multiple zones operate these doors or control flaps. They direct the airflow to the relevant zone, where constant measurements are taken of the air temperature and adjustment are made to flow of coolant. This enables the outside air to maintain a comfortable in cabin atmosphere for each occupant. All coolant eventually breaks down and becomes less efficient, particularly if it’s not maintained to Sponsored by: BY Adam Hockley, Parts Product Manager, TPS