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

Luckily, if you discover your car heater not working properly, unlike many systems on the modernistic motor car, heating systems are more or less built around the same design as they were 20 years ago - which is ultimately a basic one.

That said, there are multiple reasons why your car heater could exist busted - and working out which 1 information technology is tin be tricky.

How easy is it to gear up car heater bug?

If the problem as to why your car heater is not working is simple - and you can diagnose it - and so information technology'due south possible to fix it yourself.

Simply some bug are more complex, pregnant that to fix the problem with the heating not working in your motorcar, a visit to your local garage is necessary.

For example, a motorcar heater that does not piece of work at all could be suffering from a broken blower motor or switch, while a car heater blowing common cold air could be affected by low coolant or a clogged up heater core.

With luck, any problems y'all take with your car heater not working will go evident in warmer months, so you can fix them before winter sets in.

In well-nigh cases, motorcar heater bug fall nether two headings:

1. Car heater systems that accident air

If you find that your car heater system is blowing air simply that your auto is not heating up:

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

two. Auto 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 outcome stopping ability from reaching the blower motor.

In order to fix this, yous might have to prise open the heater box, or perhaps even elevator a section of the dashboard to access the blower.

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

Well-nigh car heater systems - i.e. ones that come with water-cooled engines - harness the coolant to heat the car 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 being filled with delightfully warm air - or at to the lowest degree, that's what should happen.

Car heater blowing cold air instead of hot air?

If you experience the chill of cold air in your car, fifty-fifty after the engine has been running for some fourth dimension (and the organisation is prepare to hot), so the following issues are likely causes every bit to why the auto heater is not blowing hot air:

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

Coolant levels

Beginning of all, cheque the coolant level - merely expect until the engine is completely cool, or y'all could exist burned.

If you observe coolant is low, there may an bereft amount moving through your heater core.

While in the short term, topping upward your coolant could address the consequence, providing a quick fix for no heat in the motorcar, the fact information technology was depression in the first 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 diddled gasket.

If a refractometer indicates the pH is off, it's likely a component has suffered corrosion and begun to leak. Miscoloured coolant, or coolant that smells off, likewise suggests an issue.

In the case of having sufficient coolant, yous can switch on your engine and allow it heat upwards, before checking the temperature at the point where the heater cadre and hoses connect.

How do you lot bank check the car coolant temperature?

It is best to use an infra-red 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 every bit the coolant merely that the other hose is cold, it is likely your heater cadre has become clogged, which will explain why your car heating is non working as it should.

If your machine has a valve in the affected hose, you lot should check to run across if information technology has got stuck.

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

In this instance, at that place 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 alloy door moving.

If you can't hear information technology motion, you lot may be looking at an issue with the thermostat switch (if your car has 1); a jammed hinge on your alloy door; or a linkage/wiring fault.

Car heater not blowing hot air?

If your car heater is not blowing hot air, then you lot probably have a faulty blower motor, although at that place's an outside chance there could be another caption.

How do you check your car blower motor?

To check the car blower motor you will need some basic diagnostics tools, which volition tell you if power is coming through. Y'all will need straight access to the motor to practise this.

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

Each automobile is unlike, and then how you piece of work out the problem volition depend on your model. Cheque your owner's manual for more than information.

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

If you believe power is reaching the motor, it'south probable that information technology has burnt out.

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

Rust and damaged wires can also exist the culprit.

In the instance that ability is going to the motor, y'all should check the blower fuse, resistor, relay and switch.

Irresolute the blower fuse

If y'all think the cause for your car heating not working is related to the blower fuse, be certain to replace it with one of the aforementioned amperage.

The fuse may have blown due to age, or it may suggest an underlying problem. If the replacement fuse (of the same amperage) does not blow, you may well have identified the problem.

Do not be tempted to supervene upon the fuse with one of a higher amperage to keep it from blowing once again.

Or… permit your garage ready it

For those without the necessary skills, mechanical bent or motivation, and for those who are merely too busy with other things, it may make a lot of sense to permit your local garage fix the problem with your car heater - particularly if the upshot is hard to diagnose.

Broken machine heater: Will it fail MOT?

If your car heater is not working, yous may well be wondering if this volition cause your vehicle to neglect the MOT.

Whilst a cleaved machine heater tin can be inconvenient (and common cold!), it is not 1 of the cadre components checked equally role of an MOT.

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

Equally as frustrating as a car heater not working, is facing bug with your car air conditioning not working properly.

Check our tips and tricks for ensuring that your car air-conditioning is working as it should.