No Heat in Car: Blowing Cold Air

No Heat in Car: Blowing Cold Air

There are a great deal of various ways a car heating unit can stop working, but the problem you’re describing is typically brought on by one of two standard issues. Either coolant isn’t flowing through your heating unit core, or air from the blower motor isn’t being directed through your heating system core. There are a variety of various underlying causes that can result in these situations where a car heater suddenly stops working, however you’re normally going to be dealing with either one or the other.

Quick Crash Course in Car Heater Operation

First of all, whatever here uses to lorries with water cooled engines. If you drive an old Volkswagen with an air cooled engine or a brand name new electrical car, then you have some kind of electrical heater that either isn’t getting power or is simply broken.

Most cars on the road still have water-cooled engines, though, and their heating systems all work on the exact same standard concept. Hot coolant from the engine passes through a heater core, which looks and works a lot like a little radiator, and a blower motor forces air through it. The air is then heated by the coolant and then, in turn, heats up the interior of the car.

This is the reason that it takes a while for heating systems to start blowing warm air. Till the engine heats up, there’s no heat for the heating system core to extract. It’s likewise the reason that a plugged heating system core, stuck thermostat, or air in the cooling system can all cause a car’s heater to blow cold.

No Heat in Car: Blowing Cold Air


Car Heater Blowing Cold Due to Cooling System Issue

There are 4 main cooling system issues that can cause a heater to blow cold:

  1. Stuck thermostat
  2. Air in the cooling system
  3. Plugged heater core
  4. Coolant not streaming through the heater core

It’s a bit more complicated than that in practice, but these are the most common concerns that you’ll run into.

Thermostats are essentially valves that open and close depending on the temperature of the coolant. In order to permit the engine to heat up, they stay closed till the coolant in the engine reaches a provided temperature level range. And if they fail to open at that point, then coolant will not circulate properly, the engine might get too hot, and you may experience an issue where the heating system blows cold.

When a thermostat sticks open, it can avoid the engine from heating up appropriately, or a minimum of prolong the warming up duration. If your heating unit was blowing lukewarm instead of cold, a thermostat that was stuck open would have been a prospective cause.

Another typical issue is when air enters into the cooling system. Considering that the heating system core is frequently the peak in a cooling system, air can move into it and become trapped. If that’s the case, then the air bubbles have to be flushed out to fix the issue.

Plugged heater cores can also cause a car’s heating system to blow cold. The best method to check for this is a non-contact thermometer, which will enable you to inspect if coolant is streaming through the heater core or not. If it isn’t, then flushing the heating unit core will frequently repair the issue.

Some automobiles have actually a valve installed in the heater core inlet line that is operated by vacuum or a mechanical cable television. If that valve is stuck closed, then that’s another factor a car heating system will blow cold.

Finally, a heating system core can become plugged in more than one method. When you hear about a plugged heating unit core, what that usually implies is that deterioration and other scrap has congested the internal tubes, and flushing will frequently clear it up. However, the fins of a heating unit core can likewise get blocked with lint, pine needles, and other detritus that handles to get into the heater box. The repair for this, naturally, is to burst or eliminate the heating unit box and clean the fins.

No Heat in Car: Blowing Cold Air

Other Reasons a Car Heater Can Blow Cold

The majority of the factors that a car heating system will blow cold relate to the heating system core, but you can also have a mechanical, electrical or vacuum problem. The specifics will vary quite an offer from one vehicle to another, but a lot of systems have some sort of mix door that changes how air flows or doesn’t flow, through the heater core.

When a mix door gets stuck, it does not matter if the heating system core is working perfectly fine. Given that the mix door is stuck, the heating system core is essentially bypassed, and you won’t get anything but cold air.

Of course, there are a variety of factors a mix door can stick, and they do not constantly stick the same method. A mix door can get stuck open, leading to all heat all the time, or stuck partially closed so that all you get is lukewarm heat.

A blend door can also get stuck due to the fact that of mechanical linkage or a vacuum line coming off, a switch going bad, or a number of other reasons. If you suspect that you’re handling a blend door issue, the specific diagnostic procedure will depend on how your vehicle’s heater is established.

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Morris T. Parson, Tech Support

Leading specialist in electronics and engineering. Author of dozens of articles on various topics from the world of hi-tech. Sound independent analysis of products, exploring new niches and global trends is his special passion.

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