At Fixya.com, our trusted experts are meticulously vetted and possess extensive experience in their respective fields. Backed by a community of knowledgeable professionals, our platform ensures that the solutions provided are thoroughly researched and validated.
hello there: there could be a couple of things wrong try checking you're blower motor to make sure you are getting any power to that point with switch turned to one of the lower setting if no power it could be the switch in the dash if there is power than it will more than likely to a bad fan blower...hope this helps you out sincerely D.Jones...
Hello...the problem is usually with the Blower Control Switch which is part of the computer climate control, the switch sends a signal to lower or raise voltage to control fan speed. The contacts inside go bad. You can remove it and check the pins on the back for any damage or corrision before you replace it. An aftermarket switch can be purchased if needed. You do not have to go to the dealer. I hope this helps.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
WHAT MATTERS IS NOW ,NOT THEN.
2nd speed blower is dead.
so is , not the blower, if high works
it is
1: bad resistor block
2: bad control
3: bad wired from there to there. 1,2.
it's not a fuse
the car CAM NEW WITH 2 OPTIONS, AUTO OR MANUAL HVAC.
THE CONTROLS ARE NOT THE SAME.
AUTO HAS NO RESISTOR BLOCK AT ALL , IT USES TRANSISTOR MODULATION. IN THE CONTROL HEAD.
SO YOURS IS MANUAL
AND CAUSE IS ABOVE, 1,2,3
LEARN TO USE A VOLTMETER.
THE BLOWER DC MOTOR IS GROUNDED, AT TERN :"A"
THis pin X
must be 12vdc, speed 2 selected.
if is 12vdc the resistor block is bad (or its wires)
manual.controls. as you can see the resistor is tricky series type
so of 2nd Resistor burns open speed 2 and 3 fail but never 4.
if 3r RES burns open speed 3 lost but not 2 and not 4.
and not 1.
speed 4 is relay controlled, and pin C lower. right.
I will post and not cover Rear AUX heater box. ok, and is and option
what part of this car has blower
is this HVAC blower failing on HIGH
is this manual version or climate control option.
fuse are blown in cab or in bay (engine)
fuses are first of high speed blower mode fails dead.
what IS A CKED ????? is see no hits in my ASE books on that part or device name in a car or a truck
2003 chevy tahoe , no engine /trans told. (this dictates fuse boxes)
my guess HVAC topic but no sure, what fan/blower or turbo this is. climate control model has left and right controls and all differenet wiring max. differ.
fuse Hvac1, hvac-ECas, and fuse BOWER< yes 3 fuse must not be blown and the BCM is the brain here.
not scanning the PCM to see BCM errors is a huge error in testing
manual controls the resistor block uses a relay to send 12dc to he blower set to HIGH. all resistors bad ,high still works.
here are the 4 things to fail;
4 is good so 3 things, 2 fuses,
#3 is relay. to fail. a volt meter finds this easy for sure reading this page in the SM.below 3 pins on relay are at 12v.
so are pin F and G 12vdc if not input to them is bad.
not counting bad wires.,
The blower motor relay is energized when the Blower Motor Control is set to the High position. This removes the blower motor resistors from the circuit and battery voltage is then applied directly from the HVAC BLO fuse (RH IP Accessory Wiring Junction Block) to the blower motor though the relay switch contacts. The blower motor then runs at high speed.
HVAC Blower Controls Circuit Description
The blower motor is a variable speed motor. The motor operates at a higher rate when voltage is increased to the maximum level.
The blower motor resistors reduce the voltage supplied from the A/C FAN fuse (LH IP Accessory Wiring Junction Block) when the blower control is set at low and medium speeds (speeds 1-4). The blower motor relay is energized when the Blower Motor Control is set to the High position. This removes the blower motor resistors from the circuit and battery voltage is then applied directly from the HVAC BLO fuse (RH IP Accessory Wiring Junction Block) to the blower motor though the relay switch contacts. The blower motor then runs at high speed.
This vehicle doesn't have a blower motor resistor ! It has a blower motor control module , if you have automatic climate control !
If manual climate control , then there is a blower motor resistor assembly !
Blower Motor Control Processor
The blower motor control processor controls the speed of the blower motor by increasing or decreasing the voltage drop on the ground side of the blower motor. The HVAC control module provides a low side pulse width modulated signal to the blower motor control processor over the blower motor speed control circuit. As the requested blower speed increases, the HVAC control module increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the HVAC control module decreases the amount of time that the signal is modulated to ground.
Air Speed - Front Control
The blower motor forces outside air into the vehicle's interior. The vehicle operator determines the blower motor's speed when the driver places the blower switch in one of 5 blower speeds. The blower motor will always operate in any switch position other than OFF, as long as the ignition switch is in the RUN position. The blower motor and mode switches are located within the HVAC control module. The blower motor OFF input is connected in series with the HVAC control module by the off blower motor control circuit.
Depending upon the selected speed, power is provided to the blower motor from either the ignition 3 voltage or battery positive voltage circuits from the fuse block. The battery positive voltage circuit only provides power when the High blower switch position is selected. Power and ground are provided to the HVAC control module by the ignition 3 voltage and the ground circuits.
Low Blower Speed
When the Low 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the low blower motor control circuit. Voltage is divided between 4 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
Medium Blower Speeds
When the Medium 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 1 blower motor control circuit. Voltage is divided between 3 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
When the Medium 2 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 2 blower motor control circuit. Voltage is divided between 2 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
When the Medium 3 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 3 blower motor control circuit. Voltage is divided between a series resistor, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
High Blower Speed
When the High blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the high blower motor control circuit. The voltage energizes the blower relay, causing the blower motor to be connected directly to the battery positive voltage circuit. The blower motor and blower motor relay are grounded through the ground circuit.
Go on you tube an check out videos on trouble shooting blower motor circuit Chevy Trailblazer EXT Blower Motor Won Turn Off
the car has 26 relays!@
and 1 to or 3 fans
are you saying the heater/ A.C blower is dead./ the HVAC?
or engine fan (its mech for rad)
or condenser fan, no symptoms posted, just relay hunts.
my guess is you dont know how the blower in the heater works.
so will cover that.
The HVAC.
First test is blower in high, failing is bad fuse.?
if lower speeds fail, (a top clue) then the blower resistor is bad. but only on the manual hvac option!
lets backup,I have full parts list on your car, here, USA. spec
the car came new with 2 class type of HVAC
manual AC with blower resistor
or
full auto system that as a new brain box, and a transistor box
that controls blower, at all times, its just a transistor. (no brains)
some cars with the full auto HVAC feature
have a self test mode.
and self calibration feature (learn) all this is in the BIG BOOK.
apples and oranges, different to the extreme.
so instead of me guessing car you bought. ill tell you to RTM
just 4 bucks, and only covers that exact year, and car only.
not a clone book as the folks post here , RAG books.
the real deal here from suzuki actual....
Usually a sign of a faulty blower resistor. The resistor changes the amperage of the circuit to change the blower speed. You can look the part up online to get a visual.
Which of these systems does your vehicle have ?
HVAC Systems - Automatic
Blower Motor Control Processor
The blower motor control processor controls the speed of the blower motor by increasing or decreasing the voltage drop on the ground side of the blower motor. The HVAC control module provides a voltage signal to the blower motor control processor over the blower motor speed control circuit. As the requested blower speed increases, the HVAC control module increases the amount of time that the speed signal is modulated to ground. As the requested blower speed decreases, the HVAC control module decreases the amount of time that the signal is modulated to ground.
HVAC Systems - Manual
Air Speed - Front Control
The blower motor forces outside air into the vehicle's interior. The vehicle operator determines the blower motor's speed when the driver places the blower switch in one of 5 blower speeds. The blower motor will always operate in any switch position other than OFF, as long as the ignition switch is in the RUN position. The blower motor and mode switches are located within the HVAC control module. The blower motor OFF input is connected in series with the HVAC control module by the off blower motor control circuit.
Depending upon the selected speed, power is provided to the blower motor from either the ignition 3 voltage or battery positive voltage circuits from the fuse block. The battery positive voltage circuit only provides power when the High blower switch position is selected. Power and ground are provided to the HVAC control module by the ignition 3 voltage and the ground circuits.
Low Blower Speed
When the Low 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the low blower motor control circuit. Voltage is divided between 4 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
Medium Blower Speeds
When the Medium 1 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 1 blower motor control circuit. Voltage is divided between 3 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
When the Medium 2 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 2 blower motor control circuit. Voltage is divided between 2 series resistors, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
When the Medium 3 blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the medium 3 blower motor control circuit. Voltage is divided between a series resistor, a blower relay, and the blower motor to achieve the desired blower speed. The blower motor is grounded through the ground circuit.
High Blower Speed
When the High blower speed is selected, the HVAC control module applies voltage to the blower motor resistor assembly through the high blower motor control circuit. The voltage energizes the blower relay, causing the blower motor to be connected directly to the battery positive voltage circuit. The blower motor and blower motor relay are grounded through the ground circuit.
HVAC Control Module
The HVAC control module is a class 2 device that interfaces between the operator and the HVAC system to maintain air temperature and distribution settings. The battery positive voltage circuit provides power that the control module uses for keep alive memory (KAM). If the battery positive voltage circuit loses power, all HVAC DTCs and settings will be erased from KAM. The body control module (BCM), which is the vehicle mode master, provides a device on signal. The control module supports the following features:
"2007 chevy tahoe ltz--rear air works ---front air does not work." Hi! I guess you are referring to the front hvac blower not blowing air at any speed and not coming out at any vents at any mode position. If this is the case, you can start with the fuses at the underhood fuseblock. Check out the three hvac labeled fuses. If found okay, and the hvac controller on your dashboard seemed to be working normally, you better check out your front hvac blower motor underneath the right IP section. You need to verify if power is reaching your front hvac blower when requested by the a/c blower controller. I hope you get lucky. If this is not for you, perhaps a few more detailed symptoms would be helpful. : )
the blower not working on settings 1-3 is the blower motor resistor. this limits the power provided to the blower motor itself to change the speed. at setting 4 it is getting full power. since it quit on 4 also, i would still say the resistor needs to be replaced first, then see if the blower comes back. you may also need a blower motor. if you have a voltmeter you can just turn the switch to 4 and see if the motor is still getting 12 volts. if it is and doesn't run, it needs a blower motor too. if it's not, then its just the resistor
use a voltmeter and win the prize, SOLVED
×