It'due south no fun getting into your car on a frosty wintertime's morning only to find the machine heater not bravado hot air. Information technology's almost as unpleasant to have a automobile heater that'due south not giving out enough heat.

Luckily, if you find your car heater not working properly, different many systems on the modern motor car, heating systems are more or less congenital around the aforementioned pattern equally they were 20 years ago - which is ultimately a basic one.

That said, there are multiple reasons why your car heater could be busted - and working out which one it is can be catchy.

How like shooting fish in a barrel is it to fix car heater problems?

If the trouble equally to why your automobile heater is not working is simple - and you can diagnose it - so it's possible to fix information technology yourself.

But some issues are more than circuitous, meaning that to fix the problem with the heating not working in your auto, a visit to your local garage is necessary.

For instance, a car heater that does not work at all could exist suffering from a cleaved blower motor or switch, while a car heater blowing common cold air could be affected by low coolant or a clogged upwards heater cadre.

With luck, whatsoever issues you have with your car heater non working will become axiomatic in warmer months, so yous can gear up them before winter sets in.

In most cases, car heater problems fall under 2 headings:

1. Automobile heater systems that blow air

If y'all observe that your car heater system is blowing air but that your car is non heating upwards:

  • At that place could be a blockage or other problem stopping heated antifreeze from moving through the heater cadre component.
  • A valve or switch could be faulty, or the heater core could be a clogged.
  • Wait until the engine has cooled down and check the coolant level, topping information technology upwardly if needed.

2. Machine heater systems that simply don't work at all

If your car heater is not working at all, you're looking at a faulty blower motor, or an effect stopping power from reaching the blower motor.

In society to set this, yous might accept to prise open the heater box, or perhaps fifty-fifty lift a section of the dashboard to access the blower.

My auto heater has suddenly started to blow cold: what should I practise?

Nigh auto heater systems - i.e. ones that come with water-cooled engines - harness the coolant to rut the machine interior.

The coolant at this point is inappropriately named, since it is extremely hot. This fluid is pushed through the heater core, which is essentially a mini radiator. In plough, air is pushed through the heater core, which results in your cabin existence filled with delightfully warm air - or at least, that's what should happen.

Car heater blowing cold air instead of hot air?

If you lot feel the chill of common cold air in your auto, even afterwards the engine has been running for some fourth dimension (and the system is set to hot), then the following issues are likely causes as to why the car heater is not blowing hot air:

  • Heater core is clogged
  • Coolant is low
  • Alloy door is jammed/faulty
  • Heater valve is jammed/faulty
  • A switch or linkage is faulty

Coolant levels

First of all, check the coolant level - merely wait until the engine is completely cool, or you could be burned.

If you discover coolant is depression, there may an bereft amount moving through your heater cadre.

While in the short term, topping upwardly your coolant could address the upshot, providing a quick set up for no heat in the car, the fact it was low in the starting time place indicates another, more serious problem. Information technology may mean a hose or gasket is leaking, or worse, that you have been burning the coolant itself, strongly suggesting a blown gasket.

If a refractometer indicates the pH is off, information technology'southward probable a component has suffered corrosion and begun to leak. Miscoloured coolant, or coolant that smells off, also suggests an issue.

In the case of having sufficient coolant, y'all can switch on your engine and let it heat up, before checking the temperature at the point where the heater core and hoses connect.

How do you check the car coolant temperature?

It is best to utilise an infra-ruby thermometer to check the car coolant temperature, since it does not require any contact.

If you discover one of the hoses is the same temperature as the coolant but that the other hose is cold, information technology is likely your heater core has get clogged, which volition explain why your auto heating is not working as it should.

If your automobile has a valve in the affected hose, you should check to come across if it has got stuck.

What if hot antifreeze is in fact passing through my heater core?

In this instance, there could be dirt or other matter stuck in the heater box, or the blend door is jammed/faulty.

How to work out if my blend door is jammed or otherwise malfunctioning?

Turn off your car heating and listen for the blend door moving.

If you can't hear information technology motility, y'all may exist looking at an issue with the thermostat switch (if your motorcar has one); a jammed swivel on your alloy door; or a linkage/wiring mistake.

Car heater not blowing hot air?

If your car heater is not blowing hot air, and so you probably accept a faulty blower motor, although there's an outside take chances there could be some other explanation.

How practise you bank check your car blower motor?

To check the motorcar blower motor you lot will need some basic diagnostics tools, which will tell yous if power is coming through. You will need straight access to the motor to practise this.

You might likewise exist facing a faulty blower resistor; relay; or switch.

Each motorcar is different, so how you piece of work out the problem will depend on your model. Bank check your owner'due south manual for more information.

Power reaching the blower motor merely heater not working in car?

If you lot believe power is reaching the motor, information technology's likely that it has burnt out.

It's possible, too, that the motor has been clogged upward with droppings to the indicate that it cannot work.

Rust and damaged wires tin can also be the culprit.

In the instance that power is going to the motor, you should check the blower fuse, resistor, relay and switch.

Irresolute the blower fuse

If you lot call up the cause for your machine heating not working is related to the blower fuse, be certain to replace information technology with 1 of the same amperage.

The fuse may have blown due to age, or information technology may propose an underlying problem. If the replacement fuse (of the same amperage) does not blow, yous may well have identified the trouble.

Do non be tempted to replace the fuse with one of a higher amperage to keep it from blowing over again.

Or… let your garage set it

For those without the necessary skills, mechanical aptitude or motivation, and for those who are but also busy with other things, it may make a lot of sense to permit your local garage set up the problem with your car heater - especially if the issue is difficult to diagnose.

Broken machine heater: Will it neglect MOT?

If your machine heater is not working, you may well be wondering if this will cause your vehicle to fail the MOT.

Whilst a broken car heater can be inconvenient (and common cold!), it is not one of the core components checked as function of an MOT.

Click here for a full list of machine parts checked at an MOT.

Equally as frustrating equally a machine heater non working, is facing problems with your automobile air workout non working properly.

Check our tips and tricks for ensuring that your auto ac is working as information technology should.