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As well as keeping you and your passengers cool during the hot summer months, your vehicle’s climate control system will help keep you warm during the colder winter months!

Long before aircon systems became popular in passenger cars, a side-effect of the engine cooling system allowed for cabin heating.

Hot water from the engine normally flows out to the radiator where it is cooled by fans. But it can also be used to heat air and blow it into the passenger cabin.

A thermostat or control valve controls the flow of hot water through a heat exchanger which is then circulated through the cabin by a blower fan.

It’s a relatively simple system but if any component fails then it means you have no heating when you might really need it!

Heat Exchanger

Also commonly known as a ‘heater core’ or ‘heater matrix’.

This component works pretty much the same as a radiator, albeit at a smaller scale. It receives a flow of hot water, heated by the engine, and the heat is dissipated through the fins.

If the fins get excessively coated with dust, or the water channels become blocked, or start leaking, then the performance of the heat exchanger will diminish, resulting in little or no warm air.

Blower Fan

The interior blower circulates fresh air within the passenger cabin, as well as pushing warm air heated by the heat exchanger into the cabin.

Blower fans are electrically controlled and use electric motors to function. They don’t last forever though , as electric components can burn out over time.

Fan resistor/regulator

The fan resistor/regulator is a component used in many modern in-car heating systems to regulate the flow of warm air into the passenger cabin.

It measures the temperature of the airflow, and if needed will reduce or increase the speed of the interior blower fan.

While generally quite reliable, those that use heatsinks can become less effective if they become blocked with dust or debris, or like with any other electrical component they can eventually burn out over time.

Troubleshooting heating problems

Fan blowing cold air

  • Thermostat or heater control valve problem, meaning heated water is not flowing into the heater core
  • Heater core is blocked or damaged/leaking, so heated water is unable to pass through

Fan blowing slowly

  • Fan blades are clogged or broken/damaged due to debris
  • Fan resistor has failed/is failing

Fan not blowing at all

  • Broken/failed fan control switch
  • Failed/jammed fan motor
  • Failed fain resistor

Replacing heating/aircon unit components

Replacing failed or non-functioning heater unit components can be quite time-consuming due to the heater/aircon unit being located within the vehicle behind the dashboard.

Heat exchangers, blower fans and aircon evaporators in many cases can designed differently, depending on whether they are installed in left-hand drive or right-hand drive models, so you should be sure to ensure that any component you order will be suitable for your vehicle.

ARKS4Cooling supplies a great number of heater cores, blower fans and fan resistors/regulators, from leading brands such as Auto Air, AVA, Febi, Mahle, Nissens and NRF. Have a browse through this website, and if you are unsure or can’t find what you’re looking for then get in touch and we’ll be happy to help and advise!