Why does my AC fan not work at high speeds?

On the low speeds, the fan relay routes the voltage thru the resistor block. When you switch to high fan speed, the relay switches over to supply full voltage from the battery to the fan motor. Tester is right.

Why are the fans on my Silverado always running?

1 month later… I have a 2014 5.3 and the fans come on extremely high, the temp gauge drops to 160. When you cut the motor off the fans continue to run on high speed until the timed power cuts off. Took it to the dealer they said it was because mu AC was out which does not make since.

Why does my GMC heater blower not work?

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. If there is a high speed relay, I can’t find it. Any suggestions?

Can a blower fan only work on high speed?

Blower Motor Fan Only Works On High Speed? Plus – Tips To Prevent Repeat Failures! If playback doesn’t begin shortly, try restarting your device. Diagnostic training videos and content hosted by ASE Master and L1 Certified Technicians.

Why does my GMC Canyon AC fan not work at speed 3?

Blower motor does not always work on speeds 1-3. Found the pin on the red wire on the plug located under the dash on the blower motor housing had a burnt and loose pin. The red wire is hot when you slect speed 3. The plug has four pins, one for each speed. Speed 4 bypasses the resistors for maximum fan speed so that is why this speed always works.

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 causes a blower fan to not work?

When this happens, you may notice that you will not feel anything blowing out of the vents at all. This may also cause the blower motor to work intermittently. A blower fan is connected to the negative battery terminal (also called ground) on one end and to the positive battery terminal through a blower motor resistor on the other end.

What to do if your heater fan does not work?

Now gently grab ahold of the red and black wire connector and wiggle it if your fan came on you have found the problem. Now if this worked for you remove the positive battery wire from the battery because the red wire at this connector remains hot.

What happens if the blower speed of an AC unit is too high?

If a blower speed is set too high, your AC might not be operating optimally. This is because the evaporator coil will not be able to adequately dehumidify the space in need of cooling. On the other hand, if the blower speed is too low, your evaporator coil is at risk of “freezing.”

Why does my Astro AC fan not work?

My 91 Chevy Astro doesn’t like to blow air on high. The AC/Heater fan works fine at lower settings but when in high it doesn’t work at all or will run for 30 seconds and then stop. I’ve replaced the switch in the dash, but that didn’t help.

Why is the AC fan on my Dodge Ram not working?

I’ve had blower motor resistors cause those exact symptoms. They’re cheap enough I’d just replace it before you do any other trouble shooting. Plus its going to go bad at some point anyway you’d just be preemptively changing it. Had the same problem. My blower motor was bad. Took it out and put 12 volts to it.

Why does my AC fan make a rattling noise?

There’s a rattling or buzzing noise coming from the condenser unit when the fan is turned on There is more than one possible cause for a noisy air conditioner. If you hear a loud rattling noise, it could be a minor issue like loose stones or debris that’s caught in the condensing unit.

Why does my Dodge Ram have low air flow?

A common problem for the Dodge Ram pick up truck is to have low airflow even though the blower fan can be heard loud and strong. Usually the problem is because of a broken fresh air door – AKA recirculate door. The fresh air door is located behind the glove box area.

How do you turn on a high speed heater fan?

Now pull the zip tie tight and cut the long end off with side cutters. Now reconnect your battery and turn your ignition switch back on and fan speed switch on high. The fan should be blowing on high, now wiggle the connector one more time the fan should stay on without interruption.

What kind of blower does not work on high?

1997 GMC C1500 Heater/AC Blower Will Not Work on HIGH. 1997 GMC C1500 Heater/AC blower will not work on HIGH. 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.

What causes a blower fan to turn faster?

The lower the resistance of the selected resistor in the pack, the higher the current that flows through the blower fan causing the fan to turn faster. The statements expressed above are only for informational purposes and should be independently verified.

How does a 3 speed blower motor work?

Older style blower motor resistor with exposed resistor elements. The blower motor resistor is what’s responsible for giving you three blower speeds. The resistor block contains three different high resistance coils. Think of these coils like a filament in a light bulb.

Why does my AC fan only work on high?

If your speed selector for your AC or Heat only works on high, or low, or if its missing any particular speed, this video will show you how to fix it once and for all. This is a fix for 2nd generation Dodge Rams (1994-2001-2002 2500/3500) Loading…

How do you know the best fan speed for heating?

Some air handlers and furnaces with variable speed motors have a feature that runs the motor at a reduced speed for the first 10 to 15 minutes of the cooling cycle. This is for humidify control, it ramps up to your normal cooling speed after the time elapses.

How does a high speed blower motor work?

The blower motor resistor is what’s responsible for giving you three blower speeds. The resistor block contains three different high resistance coils. Think of these coils like a filament in a light bulb. The coil resistance causes them to heat up, thereby reducing the amount of voltage that can flow to the blower motor.

Where is the AC blower motor resistor harness located?

If you can no longer adjust the air speed with your AC controls or your AC system no longer blows chances are you need a new Blower Motor Resistor. This COMPLETE KIT includes the Blower Motor Resistor and New Wire Harness. The AC Blower Motor Resistor is located on lower passenger side dash and is easily accessible by removing a few screws.

How are relays used to switch fan speeds?

Relays are not used to switch fan speeds, a resistor block is. Plus there are NO electronic commuted motors in a automotive application. This vehicle uses a resistor block to switch fan speeds. No relays involved in the lower speed circuit.

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.

Why does my AC fan not work at high speeds?