Have you ever experienced a situation where your heater only works on high? This is highly annoying, right? And when you have to deal with the cold weather, you can’t just put up with a heater not operating at its best. You need to find out why this happened and get it fixed quickly.

Let’s dive right into the crux, Why would my heater only work on high?

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Why Would My Heater Only Work On High?

If your heater only blows when the setting is on high, this may suggest that you have a faulty blower motor resistor. The highest speed setting may still work because in most cars in the highest fan speed settings the current bypasses the blower motor resistor.

Why Does My Heater Only Work On Full Blast?

When a blower resistor fails, the highest fan speed usually is the only one that still works because it essentially bypasses the resistor and receives the maximum amount of voltage. When the resistor is working, it reduces the amount of voltage going to the lower fan speeds so the fan runs slower.

This doesn’t happen with all cars, just those with a blower motor resistor. Some cars control the blower motor speed with a solid-state device called a transistor, which doesn’t use a mechanical connection to control current flow and therefore won’t wear out.

If you’re experiencing this problem:

Check your heater/air conditioner fuse(s) for continuity. If you’re unsure where they are in your car, consult your owner’s manual. Also check for power at the fan connector and at the blower motor itself. A wiring diagram will be helpful; if you don’t have one, look for one online or buy a service manual that has one.

Can You Fix A Blower Motor Resistor?

If your car’s blower motor is working but the fan speed is stuck on high, it may be the blower motor resistor that’s at fault. This simple part regulates the voltage to the blower, controlling the speed of the fan. If this part fails, it can cause the heater or AC fan to stop working completely or stay stuck on one speed.

The average cost to replace a blower motor resistor at a repair shop is between $44 and $55 in parts and $70 in labor costs, for a total cost of around $114 to $125. On the other hand, you can easily fix the blower motor resistor at home in about an hour (even if you’re a beginner) and for around $70.

Can A Bad Blower Motor Cause No Heat?

When a blower motor fails, it can cause the heater core to become inoperative. A failed blower motor prevents the air conditioning and heating systems from operating properly. When the blower motor fails, the air conditioning and heating systems will not function correctly. In some instances, a bad blower motor can prevent the AC system from producing cold air.

When a blower motor fails, it can cause a variety of different symptoms. The most common symptom of a problem with the blower motor is no heat coming from the heater. Other possible symptoms include no air blowing from the vents and strange noises coming from under the hood or near the vents

A failed blower motor can cause no heat on your Ford F150. Although not as common, another symptom could be no air blowing out of your AC vents. This may be caused by a failed blower motor, but it may also be caused by a bad resistor, which controls voltage to the blower motor. It’s best to have this issue checked by a trained professional, who will be able to diagnose your vehicle’s problem and get you back on the road in no time.

What To Check Heat Is Not Working?

If you turn up the heat in your car and nothing happens, it may be time to diagnose the problem. The most common cause of poor heating is a low coolant level, but you’ll need to check your vehicle’s heater hoses as well.

Check the Heater Hoses

To start, pop open the hood and look for two hoses that run from the engine to the firewall. These should be fairly large and will likely be covered with insulation. Feel them with your hand; they should be hot. If they are not, then you have an issue with your cooling system or a broken belt. Your vehicle’s owner’s manual will have more information about this.

Check Cooling System

If everything is fine with the hoses, then you probably have a low coolant issue. You can usually find the reservoir under the hood, and it will have clear markings for “high” and “low.” If it is low, simply add more coolant (if needed) and water to get it back up to “full.”

Check Thermostat

Another possible cause of a non-heating car is a bad thermostat. This means that your engine isn’t getting hot enough to trigger the heater’s controls. Also check the water pump, which is what pumps your coolant and helps keep it from getting too hot or too cold.

Check For Leaks

If you notice that your car is leaking coolant, then you may want to get it checked out by a mechanic. They can test for leaks and determine where they’re coming from so they can be fixed right away.

Can You Fix A Heater Core Without Replacing It?

Fixing a leaking heater core will always be much easier than replacing one. Since it is only a small leak in the heater core, we recommend simply sealing that leak and leaving your heater core in place. You can do this by simply by adding BlueDevil Pour-N-Go to your vehicle’s radiator when your vehicle is cold.

BlueDevil Pour-N-Go is perfect for the DIY customer who needs an easy, no mess solution to their leaky heater core. It works by simply being poured into the radiator and then circulated throughout the system, where it will seal the leak in your heater core effectively and permanently.

Can A Bad Thermostat Cause No Heat?

In cars without a thermostat, the engine will be cold before it gets up to operating temperature. The thermostat is a component in the cooling system of your car that regulates the flow of coolant. The thermostat opens and closes to allow coolant to flow through the engine or to block the coolant from entering when the engine is cold.

There are a few reasons why your car’s heater might not be working:

Faulty thermostat. A faulty thermostat could be behind your car’s heater not working. If it isn’t opening up to let the coolant flow through it, the core can’t produce heat. Thermostats can also get stuck open causing the engine’s temperature to stay low.

Frozen hoses or clogged radiator. A frozen hose or clogged radiator will keep your car from heating up because there is no way for the hot coolant to enter into the heater core. This can also be caused by a leak in any of these parts, allowing all of your coolant to escape.

Faulty heater core. The heater core could be leaking causing all of your coolant to leak out and not enough entering into it for proper heat production.

Why Does My Heat Not Kick On?

If your furnace is not kicking on, it can be an issue with the thermostat. You should first make sure that the thermostat is switched to the heating function. Next, make sure that the temperature that you have the thermostat set on is lower than the temperature in the home.

If those two things are not the problem, then there are a couple of things that you can do. Check to see if your furnace has a reset button. If so, push it and see if this will kick on your furnace.

Also, check your circuit breaker or fuse box as well as a tripped switch could cause your furnace to stop working. If these troubleshooting techniques do not work, call a professional HVAC technician.

Why Does My Car Heater Only Work On Number 4?

The heater core is the mechanism in your vehicle that heats up the air and sends it into the passenger cabin through the vents when you select your heat setting. The heater core is a small radiator, which means it’s basically a miniature version of the device that cools down the engine at the front of your car.

Because the heater core works in a similar manner to a radiator, it’s located in the same area behind the dashboard on most vehicles, and this means you have to remove some parts of the interior of your car to access it. If you want to do this yourself, then make sure you have enough time (and patience) to contend with getting everything back together again.

If you don’t have time or simply lack confidence in being able to complete this task yourself, then you can call a mechanic for assistance.