Can a blower motor relay be a problem?

One of the first symptoms of a problem with the blower motor relay is a blower motor that does not function at all. As the relay is the switch that supplies current to the blower motor, if it fails internally, then power will be cut off from the blower motor circuit, causing the motor to no longer function or blow any air from the vents.

Why does my heater not work on high speed?

Heater blower motor will not work on high speed? I have replaced the black bosch relay behind the glovebox, the blower resistor and the blower motor and still cannot get the blower to work on high. I remember in older model years of gmc’s and chevys that their was a high speed blower relay that caused this issue.

What does it mean if a relay is always hot?

As long as the relay doesn’t have a diode in it, that’s fine. It’s just a switch. Current can flow in and out either side of the switch. If the only thing you find wrong is that 87 is always hot and 30 goes to the device instead of the other way around, don’t worry about it.

What does it mean when a relay does not click?

If you hear or feel the relay click, the relay and its wiring aren’t the problem. But if it’s not clicking, the problem could be in the relay itself or in the wiring.

What are the symptoms of a bad cooling fan relay?

1. Engine running hot One of the first symptoms commonly associated with a bad or failing cooling fan relay is an engine that runs hot or overheats. If you notice that your engine is running at higher temperatures than normal, that may be a sign that the relay is not functioning properly.

Why does my AC thermostat make a clicking noise?

This noise is caused by a part called a relay, which opens and closes to turn your AC on and off. If your thermostat is secured correctly to the wall this clicking sound shouldn’t be very loud. But if you hear a loud clicking noise and the AC won’t turn on, it could mean the thermostat is malfunctioning. What causes a thermostat to malfunction?

When do you turn on the fan relay?

When the correct parameters are met, a temperature switch or the computer will activate the relay, which will allow power to the fans. The relay will usually be activated once it is detected that the vehicle’s temperature approaches excessively high temperatures.

What causes a fuse to blow on a blower motor?

If the blower motor relay develops any sort of problem that hinders its ability to properly limit and distribute power, it may cause the blower motor fuse to blow. Any sort of electrical spikes or excessive current from a bad relay will blow the fuse and cut power in order to protect the system.

What should I do if my blower motor is not working?

The blower motor is crucial to the proper functioning of your HVAC system. This video will show you how to properly diagnose your blower by using the multimeter to perform an AMP draw as well as replacing the blower motor relay. Loading…

Where is the blower control switch on the dashboard?

The blower control switch on the dashboard controls the circuit flow of the blower motor to adjust the voltage from low, to medium, to medium-high, to high. When on high, the circuit bypasses the blower resistor.

What causes a bad or failing blower motor relay?

Blown fuses. One of the first symptoms of a bad or failing AC blower motor relay is a blown AC blower motor relay circuit fuse. If the blower motor relay develops any sort of problem that hinders its ability to properly limit and distribute power, it may cause the blower motor fuse to blow. Any sort of electrical spikes or excessive current…

Why is the resistor not working on my blower?

Hi There, The resistor is what controls the speed of the blower motor, not the relay. The blower motor relay supplies power to this motor when you turn the switch to “on” that can sometimes fail. When this happens, you may notice that you will not feel anything blowing out of the vents at all.

How does a high speed blower motor work?

In the highest fan speed state, the blower resistor is bypassed completely and the fan is effectively connected directly to the car’s battery, allowing maximum current to be supplied to the blower motor.

What causes a blower motor to stop working?

In a situation where the motor doesn’t work on any speed, the most likely causes are: a blown power supply fuse, a bad motor ground connection, bad motor speed control module or a failed motor. On all systems, a failed blower motor is least likely. Blower motors generally don’t fail out of the clear blue.

How does a blower motor work in a car?

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.

When to replace a heater blower motor switch or relay?

When the motor gets old and tired it will draw more current through the wires than a new motor. It may still draw enough current to blow the fuse after it runs for a while. In that case, a motor replacement is in order. Step 1: Disconnect the battery. Put on your safety glasses and disconnect the battery at the negative cable.

What to do if your heater fan relay is not working?

Put everything back together the way it came and re-program the code into the radio if needed. If you’ve checked the fuse panel, and the fan motor doesn’t run at all, or if it runs only on the lower speeds, the blower motor relay may be at fault. Relays are used to carry electrical loads that are too large for conventional switches.

Why does my car have no air in the vents?

Step 3 – A fan blower motor is controlled by either a switch in the passenger compartment or by a computer. If this fan motor is starting to fail it will cause the fan motor to run at a lower speed resulting in low air flow. To test this condition an amp meter is needed, connect the meter lead to the power wire of the fan motor.

What should the voltage be on a blower motor?

If those are OK than backprobe the blower motor connector and check for power on terminal 1. Check terminal 2 for a variable voltage, this should be 12v with the fan control knob on off and 5v or full ground on full. If that checks out replace the blower motor.

What happens when a blower motor relay wears out?

Without it, the AC system will not be able to circulate any heated or cooled air. The blower motor relay controls the current used to power the blower motor, and is subject to the constant on and off switching. Over time, it can eventually wear out.

Where are the fuses on a blower motor?

Check fuses 10 & 11 in the underdash fusebox. If those are OK than backprobe the blower motor connector and check for power on terminal 1. Check terminal 2 for a variable voltage, this should be 12v with the fan control knob on off and 5v or full ground on full.

What are the symptoms of a worn out blower motor?

One of the symptoms of a worn out blower motor is that it can intermittently produce a loud screeching noise when running. How to test a blower motor? If the blower motor doesn’t work at all, the blower motor itself must be tested first. Typically it’s done by measuring the voltage at the blower motor connector when it’s turned on.

Where is the blower motor resistor located on a car?

It’s located inside the dash, often on the opposite side of the steering wheel or inside the engine compartment on the firewall. A blower motor resistor or a blower motor control module is the part that controls the speed of the blower motor.

What happens if you have a bad blower motor?

The blower motor is the component responsible for pushing air through the vents of your vehicle’s heating and air conditioning systems. Without it, the AC system will not be able to circulate any heated or cooled air.

What happens when you change the fuse on a heater blower?

If the fuse is blown, replace it and then try the blower. If the fuse blows right away, your car may have a bad blower motor or some other problem in the system. If the blower works when you change the fuse, you may not be out of the woods yet. When the motor gets old and tired it will draw more current through the wires than a new motor.

How to fix a blower motor or relay problem?

Blower Motor or Relay Problem? 1 1 or #2 speed 2 4. Reach inside squirrel cage and give the fan a gentle push 3 5. Fan spins to life and works the remainder of the trip, all day, and sometimes for multiple days 4 6. Sometime later (sometimes days later, other times the next morning) start back at 1.

How to replace a heater motor switch or relay?

Step 1: Replace the switch. At this point you should have the switch in a position to easily disconnect it. Be careful, there are usually locking tabs on the connector that have to be squeezed before it will release and pull off. The plastic connectors are brittle and break easily.

Why does my central AC unit turn off?

My central AC unit decided to stop on the hottest day of the year. It would start and run normally for a few minutes and then the blower would shut off. After checking the breakers, thermostat and overflow shut off (did not have one) I saw something about a blower motor capacitor.

What should I do if my blower motor stops?

Replace blower motor. If you have a variable speed blower motor, replace the blower motor speed control module. If you have a three or four speed blower motor, remove the blower motor relay. If the motor stops, replace the relay. Alldatadiy.com and Eautorepair.net are professional-grade shop manuals—period.

Why does my blower not work at high speeds?

Blower works on slow speeds, but not on high speed. Check for bad fuse or bad high speed relay. Swap the high speed relay with another relay with the same part number. Also, check the fuse for the control side of the high speed relay. Make sure the ground side of the high speed relay is working. Blower works on some speeds but not others

Why is the blower motor not working on my car?

My car has an automatic transmission. Hi There, The resistor is what controls the speed of the blower motor, not the relay. The blower motor relay supplies power to this motor when you turn the switch to “on” that can sometimes fail. When this happens, you may notice that you will not feel anything blowing out of the vents at all.

Can a delay on make be used on a blower motor?

A normally open delay-on-make timer can be used to operate a blower motor which is to be delayed for a specified amount of time after an electric, gas, or oil heater has been started. This avoids movement of cold air into a room that is occupied by people. Find your new HVAC system parts at Amperite.

Where does the power from the blower motor come from?

The power for the blower motor comes straight from a 30 amp fuse that is hot in run. It is the fuse directly above the flasher. This black box contains relays. It’s located just behind the passenger side headlight and in front of the container for the air filter. Here’s the relay box without the lid on it.

What are the symptoms of a failed blower motor resistor?

Blower motor resistor problems. Problems with a blower motor resistor are common in many cars. The most common symptom of a failed blower motor resistor is when the heater fan only runs at high speed and doesn’t work at low speeds.

When to test the blower motor resistor in a Ford?

If the blower motor in your Ford vehicle only works in one speed (usually just high), then there’s a good chance that the blower motor resistor is bad and behind the problem. Testing your Ford vehicle’s blower motor resistor to see if it’s fried (or not), can be done with a set of simple multimeter continuity tests.

Can a blower motor relay be a problem?