9 reasons why your vehicle has no heat

So your car heater stopped working, yes I know it’s not a good feeling. It’s weird because during the summer you really don’t know how important warm air is during those warm mornings when you get into your vehicle and drive to where you got to go. likewise, you realize pretty quick when there is no heat when the weather starts changing that not having warm air becomes a safety factor. In this article we will explore the possible 9 reasons why your vehicle has no heat.

How Your Vehicle is Heated

This is my experience, and this is how I diagnosed my vehicles heater problem, and I have came up with  9 reasons why your vehicle has no heat. Depending on the vehicle you drive, there is not much difference in the way a heating and cooling system works. When we talk about the heating system, it’s really a simple setup where the vehicle is warmed by the vehicles engine coolant.

As the coolant circulates throw the engine, the coolant is warmed and passes through hoses going into what is called the heater core, which basically acts like a radiator. From there, there are sensors that instructs a series of values and doors to open and close depending if you want a certain amount of hot air to enter through your vehicles ventilation system. Likewise, the A/C system works with the same duct ventilation that the heat is coming out from. So if one or the other goes out, there is a noticeable difference.

As the warm air passes through the heater core, there is a blower fan that blows the air directly from the heater core entering through ducts that lead to what is called a blend door that opens and closes depending on how much warm air you want in your vehicles cabin. This is the same way your air conditioning system works, but it functions off the A/C compressor where it dries moisture from the cabin air filter leaving behind cool air. Anyways, The heater system is then controlled by your dials that send a signal to the blend doors to adjust to how much heat you want entering into your cabin.

Basically, all vehicles work with this system, where you may have two or three blend doors located inside your dashboard. Usually older vehicles have easy access and you can visible see where the ducts come and go by looking directly under the dash, as well as your heater core. Where it gets tricky is how newer vehicles have everything interwoven where if you want to fix or replace anything, you need to take a part everything. Sometimes you may even need to go as far as removing your front windshield in order to remove the dash cover.

A lot of YouTube videos are great at explaining different ways of getting around things if you are good with working with your hand and tools, if not some jobs are better to be diagnostically tested to make sure the part you may suspect is actually bad. From the many videos and forums that are currently available, it seems that typically the blend door itself or blend door actuator are the first to go out.

This is because the doors or “blend doors” open and close with small motors which are know as blend door actuators where the gears eventually strip away and stop working. You will know this when you go and turn the dial for full heat, and only cool air comes through or visa versa. Most of the time you can check this by actually listening to see if the blend doors are in fact opening and closing, or if not, if you can see the blend door motors, you can feel if they are in fact functioning. Furthermore, if they are stuck in either position, you will get warm or cold air depending on the position they are stuck at. 

Possible 9 Reasons Why Your Vehicle has no Heat

Diagnose The Problem

So basically, here is a list of 9 reasons why you may not have not heat, if you want to check this, research how many blend doors your vehicle supposed to have, and get an idea where they are located. Once you figured this out by removing some simple panels,

  1. Put the heater on fully and if you have a stethoscope apply it on the motors to hear if they are working
  2. If they are not working, check your HVAC fuse to see if it’s not blown.
  3. If the fuse is good and you hear the blend door motors working, but don’t hear the blend door opening or closing, you got a stripped, or broke blend door motor, gear, or door.
  4. If you don’t hear the blend door actuator working, its either a loose wire, bad connection, or motor went out.
  5. If everything is working but still no air, check the heater blower to see it is functioning as required, and check connections.
  6. If the heater blower is working, more than likely you have a bad, or clogged heater core where you will notice slight heat coming through, but not full heat. Usually you can check this by removing both hoses and putting a water hose to one end with very minimal pressure to see if water is passing though. If the water is coming out dirty or dark something is going on with the core and maybe needs to be replaced.
  7. If the the heater blower is fine, check coolant levels because if the coolant is too low it will not reach the heater core and provide no heat.
  8. If this check out, then you may have a bad thermostat, or some wires that may have been frayed, have fallen off, or bad connection inside the engine compartment.
  9. If all else fails, it will probably be a good idea to take it to a certified mechanic to properly diagnose the problem.

Although this may be a huge headache, if you can trouble shoot the problem you can save yourself a lot of money because if it turns out to be something simple, you will still be charged hundreds of dollars. This is because most dealers and automotive mechanics know that you don’t know what the exact problem is, and in turn they will charge you for something that doesn’t need to changed.

Likewise, if you take your vehicle to a specialist and you suspect that one or more of what has been mentioned above, it wouldn’t be a bad idea if you can ask them to inspect the different moving parts that are known to fail. Since everything is already taken a part, why not check, it’ll save you money down the road without all the headaches. Advanced auto parts has a huge selection of parts at a decent price check em out.

Alternatively, there are times when your heater has no problem at all, but it may be the result of some sort of additional installation. This may include the customization or replacement of a steering wheel, radio, bad instrument panel, or something different altogether where parts may have needed to be removed to be properly fixed. If this is in fact a scenario that has come up for you, and you knew prior that your heater did work, somewhere down the installation, or removal something was put back correctly, or broke in the process.

This is exactly what happened to me, a new stereo was installed and during the removal process, many things needed to come a part in or order to reach the place where the radio needed to go. This resulted from a single blend door actuator not be connected when everything was being reassembled. All the while, I checked fuses, coolant levels, and everything else that it could of have been. The only thing I couldn’t figure out at first was where all the blend door actuators were, and in the process I noticed one was not working and thought about the removal of the part which was high up under the dash.

It was until I followed the connection where I felt it loose because I could not visually see it, I then snapped the connection back together, and finally figured out what was wrong. It worked like a charm, but if I was told the steps of what to look for, I could have fixed it sooner rather than spending a whole weekend stressing about what it might have costed me to repair.

This was my learning journey of how to diagnose a heater problem where hopefully I have learned enough to help some one that may be having the same problems. With a little bit of research and know how, you to can figure it out when you run into this situation. Have any questions, feel free to ask. Find out more at Drivewayjunky.com

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