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5 Convincing Reasons Car Heater is Blowing Out Cold Air instead of Heat

Reasons Car Heater is Blowing Out Cold Air instead of Heat

We tackled last time about your vehicle’s A/C blowing hot air  when it is searing heat outside. Now, we are going to discuss your car heater blowing out cold air and not heat when it is frigidly freezing cold outside and you need to be warmed inside your car. This car issue may make people wondered why their vehicle’s heater suddenly blows the cool air, especially in the middle of bitterly cold winter where you are supposed to be feeling the warmth and not the other way around.

But you are not the only one who suffers from this dilemma, unreliable car heaters may sometimes give you a headache when you least expected. Automotive heaters, just like home heating systems, have several working parts that work together to keep you warm inside your car. 

As a consequence, there are several factors on why your car heater may get problem supplying you hot air and that is what we are going to discover in this article. It is better that you know something about your car than relying upon service centers that could charge you hundreds of dollars just for this fix.

Before you decide to do anything fancy, you may want to do some check up on the parts and components of the heating system. This will allow you to know the real reason on why your heater blows out cold air and spare you from spending additional cost for buying parts which you may find later is not necessary.

5 possible reasons why your heater blows out cool air

Here are some of the most common reasons on why your heater may blow cold air instead of a hot one. Remember that, if any one of these issues is present, you will certainly experience cold air rather than heat.


  • Leaking water
  • Stuck up heater core tubes
  • Dehydrated coolant
  • Malfunctioning thermostat
  • Bad or clogged up heater controls

1

 Leaking water

Water leaks on car heater

Water leak

Water leaks on car heater are the least common cause of cold air coming out of the heating system. There are several spots where leaks could come from. Check your hoses, water pump, and even the radiator for possible damage. If you can’t find any leak with these systems, do some more effort and check the next possible causes.

2

Stuck up heater core tubes

Stuck up heater core tubes


As we have learned from our previous article about heater core, it is made up of brass or aluminum tubing where hot coolant circulates and travels, then the air is blown or dispersed by a fan that heats up your cabin. When this tubing is clogged up by dust, dirt, and other debris, there is no way that the coolant will circulate, hence heating your car will seize. The heater core is responsible for your car’s heating and defrosting actions, it will stop operating when the tube clogs up.

The best thing to do when this happens is to consult your car technician for a possible solution. If replacing the heater core is inevitable and you may want to do it by yourself to spare you from paying a large amount of labor fee, you can read our previous article on how to replace a heater core here and see the list of the leading brands of heater core that will suit your car.

3

Dehydrated coolant

Dehydrated coolant

Dehydrated coolant

Almost all vehicles used liquid coolant to cool down the engine, more importantly during the searing summer months. Coolants are primarily made up of 50% antifreeze and 50% water. During winter season, whenever you crank up your heat, the hot coolant is diverted into the heater core to warm up your cabin before it is cooled in the radiator.
When you have not enough coolant, there will be problem cooling the engine and heating your interior. Check your coolant level to know if you have to add the liquid. When your car has low coolant level, it can’t send hot liquid to the heater core to produce warm air.

> View more: How to Replace a Heater Core in Under 5 Hours

4

Malfunctioning thermostat

Malfunctioning thermostat

Malfunctioning thermostat

When you turn on the heater, you can feel the cold air for the first few minutes as the engine needs to be warmed up in order for the coolant to heat up and delivers warm air in the cabin. If you felt that cold air is being pumped out of your heater for a longer period of time, you may want to check your thermostat gauge.
If the gauge stays on the “C” although the engine had warmed up, you might have a malfunctioning thermostat. The thermostat gives signal to the car’s heater controls and when this device is not working, there will be no coolant that will be sent to the heater core while the air it blows out remains cool.
An easy fix and replacement with this thermostat is basically cheap. It is better to install a new one to keep your heater working again. One cheap but high-quality alternative is the GM Coolant Thermostat. Check this one out on Amazon Prime for free shipping.

5

Bad or clogged up heater controls

If there seems to be no problem with your heater core or the coolant is at its right level, you might want to replace some or all of the control buttons or the heater control valve. These controls suffer occasional tear and wear as time goes by. They can get clogged or stuck up with dirt, patina, and other debris associated with electrical controls.

While the heater control valve works as the switch that turns the heat intermittently, you may experience blowing cool air inside the cabin instead of hot air.

There are several compelling reasons on why your car heater is blowing out cold air instead of heat, but you could also know the causes when you want to. On this regard, knowing something about your car will surely brings you knowledge that would spare you from high cost of repair when everything’s gone wrong due to negligence.

You can send us your comments about this article and we hope you learn something from it.

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Blake Nicholas

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