One of the most common problems with an automotive climate control system is a lack of blower pressure or no blower at all. That means a trickle out of your vents instead of the rush you asked for. It will still work with no fan, and you'll usually still be able to control the temperature of the air that is blowing or trickling, out.
But a climate control system with no fan to push the air around is anything but controlled. As did the author of this letter, you want your fan back.
Check out what he's been through, and why he should have asked an expert from the start. My problem is on a Dodge Caravan 3.
The trouble relates to the blower motor and its activation. My blower motor does come on. The Haynes manual says the blower is activated by a relay. I need to find the location of this front blower relay and the fuse that powers it.
I work in the telephone business and am very familiar with DC wiring. Dodge owners manual shows the 40 amp blower fuse, 25, but does not mention any blower relay in the PDC. All the relays in the PDC have designated legends on the cover, but none indicate they are for the front blower relay. The Dodge owner's manual contradicts this and shows no 10 amp fuse for the purpose of a blower relay, inside the junction box. Note, there is no burnt or corroded wiring.
I just have to find the blower relay and its fuse. Can you help? This is often the case. Your vehicle should have a complete relay diagram showing the location of all of the vehicle's electrical components such as fuses and relays. To fix any blower, the first things to look at are the fuses, relays, and electrical connections. All of these are fairly easy to check. However, attempting this without all of the info you need, destines your electrical troubleshooting process to failure.The coolant system on a car is made up of a network of hoses which carry coolant around the engine.
The coolant is forced round the hoses by a water pump, and the engine is cooled by the water passing through channels within the engine block. A cold engine is inefficient, so it is fitted with a thermostat to get it to warm up quickly. Once up to temperature the thermostat opens and the coolant flows around the whole system.
The radiator and thermostat work in conjunction to keep the water at the optimum temperature, which is why once your car warms up, the temperature gauge should remain relatively static.
If the coolant gets particularly hot, the next line of defence is the radiator fan. This increases the flow of air over the radiator, and so increases it's effectiveness. Coolant level Take a look at the level in the expansion tank, preferably when it's cold. Learn how to check your coolant level here. Is it reading correctly?
Modern cars have a coolant temperature sensor which informs the temperature gauge. These sensors can fail. Often they will be flagged when you read the OBD fault codes. Thermostat A common cause is a faulty thermostat. If it's permanently stuck open then the car could be 'overcooling'. You can remove the thermostat and test it in a pan of hot water, it should open just before it reaches the boiling point — usually around 95 deg C, then close as the water cools.
If it's not moving, then replace it! Learn more about replacing your thermostat here. To rectify this set the heater controls in the car to maximum heat, remove the header tank cap and fill to the correct level. Now start the engine without replacing the cap and idle for a few minutes.
The coolant level may drop as the thermostat opens. Keep topped up to the max level. Squeeze the top radiator hose to help air pump around the system with the engine running taking care to avoid any moving parts, in particular the radiator fan, which could come on suddenly without warning. It should 'self bleed'. Once up to temperature replace the cap and test drive. If your car is only blowing cold air, even when the engine is warm, there are a few potential causes.
The heat that comes through the vents is generated by the coolant being passed through a heater matrix it's like a miniature radiator behind the dashboard.
If it's not blowing hot air check the following:.
Symptoms of a Bad or Failing Blower Motor Relay
Low coolant may prevent it from circulating through the heater matrix. Is there an air lock? Follow the bleeding process outlined above, ensuring the heater controls are set to maximum heat.
Heater control valve When you set the temperature to hot, air being passed over the heater matrix should be ducted into the cabin. If it isn't it could be that the heater control valve is not working and needs to be replaced, or on older cars a physical flap which alters the path of the air could be broken, or disconnected from the controls.The blower motor resistor is an electrical component that is a part of the vehicle's heating and air conditioning system.
When fan speed is changed via the knob on the instrument cluster, the blower motor resistor changes setting, which changes the speed of the blower motor. As the fan speed is one of the most frequently adjusted settings of the air conditioning system, the blower motor resistor is put under constant stress, which can cause it to eventually fail. A failed blower motor resistor can cause issues with the operation of the entire heating and air conditioning system. Usually a bad or failing blower motor resistor will produce a few symptoms that can alert the driver of a potential issue.
A common symptom of a faulty blower motor resistor is a blower motor that is stuck on one setting. The blower motor resistor is the component directly responsible for controlling the blower motor fan speed.
If the resistor shorts or fails, it may cause the blower motor to remain stuck on one fan speed. The heating and air conditioning systems may still function at one speed, however the resistor will have to be replaced in order for full functionality to be restored. Another common symptom of a faulty blower motor resistor is a a blower motor that does not function on certain settings.
How to fix a car heater
This can also be caused by a blower motor switch, so a proper diagnosis is highly recommended if you are uncertain of what the issue may be. Power to the blower motor is fed through the blower motor resistor, so if it fails or has any issues power can be cut off to the motor.
A blower motor without power will not be able to produce any air pressure, and as a result the heating and air conditioning system will be left with no air coming from the vents. As the blower motor resistor is the component directly responsible for powering the blower motor, when it fails it major issues with the blower motor and the heating and air conditioning system can be experienced.
If your vehicle is displaying any of the symptoms above, or you suspect that your blower motor resistor may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the component should be replaced. The most popular service booked by readers of this article is Vehicle Engine Cooling Inspection. Our certified mobile mechanics make house calls in over 2, U.
Fast, free online quotes for your car repair. Schedule Vehicle Engine Cooling Inspection. Service Area.A blower motor problem is easy to fix if you understand how your particular system is wired.
Here are the blower motor fix steps:.
Do you set the temperature and the system keeps that temperature or do you have to adjust the temperature up manually and then turn it down once the cabin heats up? Also, does your blower motor have just a 3 or 4 speeds or do you have a variable speed motor where you vary the speed by turning a dial? Why do you need to know that? Because most automatic systems use an electronic motor controller while manual systems usually use a blower motor resistors to obtain 3 or 4 different speeds.
Heating systems with just 3 or 4 speeds use a motor resistor along with the speed switch to regulate the motor speed. The resistors are arranged in series to reduce the voltage in steps, depending on where in the series you apply power. Blower resistors can burn out. When that happens, you lose that speed.
So you may have high speed, but no lower speeds. A variable speed motor is controlled by a digital speed controller. In most cases, the controller receives a digital input from the speed switch or HVAC control head. To obtain the requested speed, the motor controller rapidly pulses the ground circuit on and off.
So a half speed driver request will result in the blower motor controller pulsing the ground connection off twice as often as when the fan is running at full speed. Carmakers use these three common wiring methods to supply power and ground to the blower motor in a manual system using a blower motor resistor. In one design, the car maker supplies battery power to the speed switch, which switches the power to the appropriate connection on the blower motor resistor.
In those applications, the motor resistor reduces power for the slower speeds and the blower motor has a permanent ground connection to complete the circuit. See the wiring diagram for that setup below. Or, carmakers can supply power to the motor and control blower speeds on the ground side of the circuit. Or, carmakers can opt for a motor resistor AND a high speed relay. See the wiring diagram below for that setup. Instead they use a blower motor speed control or a power transistor.
Variable speed motors are most often used in vehicles with automatic climate control. In those applications, the HVAC control head is a digitally controlled unit and uses various sensor inputs to determine when to supply heat.
The module uses that information to pulse either power or ground to the motor. See the wiring diagram below for a typical variable speed motor setup. On all systems, a failed blower motor is least likely. In most cases, they start to fail by making a high pitched squeal or screeching noise that indicates the bearing is failing. The squealing noise happens most often in the winter during cold startups and may disappear as the motor heats up.
Start by checking the blower fuse and HVAC controller fuse.Even if you live in Florida, Texas or California, these days you need your car's defroster to work properly to fight those early morning chills, and if you live up north a working heater can be a matter of life or death.
Read on and we will cover how your cars heater and engine cooling system work, what the most common causes of it not working, and how to fix it. The coolant is forced around the passages by a water pump. A thermostat prevents the coolant from flowing until the motor gets warm enough. Rubber hoses carry the coolant from the motor to the radiator, and also to the heater core, which is basically a smaller radiator under the dashboard.
The radiator uses the outside air and a fan to cool the fluid in the system, while the heater core uses the heat from the coolant and a fan to warm the air inside the car.
For the cold engine to warm up quickly, it is fitted with a thermostat. When cold the thermostat restricts the flow of coolant to prevents it from entering the radiator.
Once the engine is up to temperature the thermostat opens and the coolant flows around the whole system. The thermostat, and clutch or electrically controlled cooling fan work in conjunction to keep the water at the optimum temperature.
If the temperature gauge isn't moving much from the lowest reading, or the car runs poorly for more than a few minutes on a cold day, the cooling system may not be working properly. There are a few potential culprits for why your car engine coolant may not be heating up:. Now start the engine without replacing the cap and idle for a few minutes.
Watch for the coolant level to drop as the thermostat opens. Keep topped up to the max level with the engine running. Squeeze the top radiator hose to help air pump around the system taking care to avoid any moving parts, in particular the radiator fan, which could come on suddenly without warning.
Between the engine heat and the water pump, all the air should be forced from the system. Once full and warm, replace the cap and test drive. A car heater that isn't working could be caused by several simple issues.
Here is what to check if your heater or defroster isn't working:. Go to front page. Search results Search Haynes.
Year Year Make Make. Model Model. And How To Fix It. There are a few potential culprits for why your car engine coolant may not be heating up: Coolant Level - The first think to check is the coolant level!When winter arrives, the last thing you want breaking down is your car's heater because not only is a frosty car inconvenient—it's also dangerous. This genuinely becomes a safety hazard because heat is needed to remove ice and fog build-up on your windshield—not to mention that extreme cold for extended periods is extremely dangerous.
So what happens if your car heater zonks out in mid-January? Here are a few things to try before heading to the mechanic. This is a two-for-one space saver as this jump starter from Anker also serves as a battery back for smartphones.
It's always good to have some extra juice on hand. Compact and sturdy, this shovel for SOG should be more than enough to help dig your car out of any snowy conditions. This blanket will help keep you warm until help arrives. The coolant absorbs the heat from the engine, causing it to become hot.
This heater core then passes the hot air it generates into the vehicle with a blower fan. Many different things can go wrong here causing the whole system to work poorly or not at all. Checking to make sure the engine warms up properly is number one on the list. When driving, an engine typically takes about minutes to reach its proper temperature. To help engines warm up fast and then keep it at a steady temperature, manufacturers use a thermostat to control the flow of coolant.
If the engine is cold, the thermostat will restrict the flow of coolant into the engine, allowing it to warm up quickly. Replacing a thermostat is a relatively easy DIY project on some cars but can be difficult on others. Buildup of grime is fairly common in coolant systems, so there could be a restriction somewhere. Fixing this can be as simple as a fluid flush.
A different reason for the heat to not work would be a lack of coolant going through the engine. One of the more obvious problems would involve the blower fan not pushing any air out of the vents. Whatever it may be, consulting forums specific to your car and speaking with a mechanic should help set you on the path of being warm and happy again. Type keyword s to search. Today's Top Stories. Buy Now. Folding Shovel Survival Shovel. Twin Wool Camp Blanket.
Windshield DeIcer. If you're having trouble getting the ice off your car, this will help things along. Become a Car Yoda. Advertisement - Continue Reading Below. More From Essential How-To.To determine the cause of a blower fan failure, isolate the motor, and perform some basic electrical tests. Bring broad knowledge of electricity and specific knowledge of the use of electrical testing equipment. A wiring diagram for the specific vehicle is also helpful. Observe safety precautions while working with electricity.
Check fuses first. Fuse failure often causes component failure. Replace fuse if blown; if not, proceed to Step 2. Check for power at the motor itself.
Blower motor, resistor: how it works, symptoms, problems, testing
Using a test light or a multimeter set on volts, unplug the blower motor. Keeping the black lead on a good ground, usually a bolt on the engine block, and the blower switch turned on, use the red lead to probe the plug that usually attaches to the blower motor. The meter should read between 9 and 11 volts or the test light will light up. If the voltage is right or the test light illuminates, go to Step 3.
If not, skip to Step 4. Test the connection to the blower motor. Take two jumper leads, one black and one red. Connect the black lead to a ground and then to the blower motor assembly. Connect the red lead to a power source and then to the leads on the motor side of the disconnected connector.
If the motor turns, the connector is bad. Repair the connector. If the motor still does not turn, the motor is bad. Replace the motor.