Question about 2004 Chevrolet Silverado

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Blower motor is intermittent, disconnected plug to motor & checked voltage at plug which is battery voltage without motor running. It has a 3rd connection but I don't know how to check to see if I'm getting varible voltage for speed change in motor.

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Id hot wire motor to get it turning and drive around and see if it continues to run. It may have nearly dead brushes. Easiest way to check variable voltage is to pull the resistor and look at it if unbroken, it's OK. Is motor grounded properly?

Posted on Mar 11, 2009

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A/c blower motor works if I pull power and plug back in until I cut engine off. Then I have to repeat process

Daryl, You may want to check the blower relay/ just switch with one of same type and try and if OK, problem could be the blower motor, wires/plug loose,damaged,burnt or a faulty blower motor resistor. Second link has some trouble shooting of a overheating wire problem, that is to be common in these trucks. Check the attached links,instruction and guides, Good luck
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Jul 19, 2016 | 2003 Chevrolet Silverado 1500

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Location of heater relay on 2003 ford focus.

There is no relay, according to my info. At the blower motor, green wire is voltage, fuse protected, goes hot with key on. Black wire is ground. The blower speed control switch is part of ground circuit. There are resistors for the lower speeds. Hi speed doesn't use a resistor. If you have good voltage and ground at blower motor and no blower action, suspect the blower motor. Any motor that uses brushes, sometimes you can tap on suspect motor, and it will run intermittently. Sign of bad brushes.
You may be able to use jumper wires to blower motor connector for voltage and ground, from the battery, just to see if blower motor will run? If it won't run, suspect blower motor. If you use jumpers, use an inline fuse, just in case.

Oct 15, 2015 | 2003 Ford Focus

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Why does blower on A/C sometimes work and sometimes don't on my Saturn 2007 aura

Blower motor control processor would be a good guess but I'm not in the guessing business , you need to test power an grounds for lose connections or corrosion , check for DTC'S in the HVAC control panel an if none , there are three different diagnostic flow charts from Saturn service info .
Blower Motor Always On Blower Motor Inoperative Blower Motor Malfunction
Myself I'd say Blower motor malfunction flow chart !


Did you perform the Diagnostic System Check - Vehicle?
Go to Step 2
Go to Diagnostic System Check - Vehicle


Place the blower motor switch in each speed position.
Does the blower motor operate at the desired speeds?
yes / no
Go to Testing for Intermittent Conditions and Poor Connections
Go to Step 3


  1. Disconnect the harness connector of the blower motor control processor.
  2. Measure the voltage between the battery positive voltage circuit and the ground circuit of the blower motor control processor.
Does the voltage measure within the specified range?
10-14 V yes / no
Go to Step 4
Go to Step 6


  1. Connect the blower motor control processor.
  2. Disconnect the harness connector of the HVAC control module.
  3. Measure the voltage on the blower motor speed control circuit.
Does the voltage measure within the specified range?
4.5-5.5 V
Go to Step 7
Go to Step 5


Test the control circuit of the blower motor control processor for a high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
Go to Step 12
Go to Step 7


Test the battery positive voltage circuit of the blower motor control processor for a high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?
Go to Step 12
Go to Step 9


Inspect for poor connections at the harness connector of the blower motor control processor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
Go to Step 12
Go to Step 10


Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?
Go to Step 12
Go to Step 11


Repair a high resistance in the ground circuit of the blower motor control processor. Refer to Circuit Testing .
Did you complete the repair?
Go to Step 12


Replace the blower motor control processor. Refer to Blower Motor Control Processor Replacement .
Did you complete the replacement?
Go to Step 12


Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.
Did you complete the replacement?
Go to Step 12


Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 2
Good luck , hope this helps !

Jul 11, 2015 | 2007 Saturn Aura XR Sedan

2 Answers

What causes the interior blower motor to run & quit sporadically even with no A/C running?

Hi Milton, Sounds like another problem with the motor or the power supply to it. Check the connections first and then the motor. Regards John

May 28, 2014 | 1992 Honda Accord

1 Answer

2005 colorado new blower motor stop running, hooked the motor to battery and it works?

Replace the blower motor resistor. It is right there with the blower.

May 11, 2014 | 2005 Chevrolet Colorado

1 Answer

Blower motor won't run

Check for voltage at blower motor connector. If battery voltage is present....remove and replace blower motor.

Nov 26, 2012 | 1994 Ford Taurus

1 Answer

2006 trailblazer ac only blows on #5 speed. Replaced blower resistor & control panel. Also on any lower speed ip lites up i.e. abs, traction control,e-brake &seat belt?

****, you can check some more but from what I am reading your problem could be related to a faulty ignition switch. I am sending you a copy of some fixes.. you can compare to your condition..
Best of Luck to you..

2006 Chevrolet Trailblazer LS 4.2L, Vin S, Eng Cfg L6
Customer Concern: No blower motor function. AntiLock Brake System (ABS), Red Brake Warning Light (RBWL), Traction lights all on. Radio does not work. Tests/Procedures: 1. Check for battery voltage at fuses #31 and 39 in Rear Fuse Box under the rear seat.

2. If the voltage value is less than battery voltage, check the Orange wire at the 48 cavity connector located at the base of the steering column at pin D1.

3. If the voltage is low at C201 check the voltage at pin "G" of the ignition switch.

Potential Causes: Ignition Switch

2006 Chevrolet Trailblazer LS 4.2L, Vin S, Eng Cfg L6
Customer Concern: ABS, Low track light comes on intermittently. The heater blower motor quits running, 4WD not working. No communication with the ABS. If you disconnect the ABS computer and plug it back in, it may work. Tests/Procedures: 1. Test voltage at HVAC 30A, 4WD 15A, HVAC 1 10A, BRAKE 10A, TBC RUN 3A labeled fuses in the rear fuse block during the problem.

2. Inspect connector 101 38 cavity connector mounted along the underhood bussed electrical center. This harness may be routed tightly around the underhood fuse block, causing chafing or connector terminal contact that could induce any of the concerns listed.

3. Clean and secure ground G110 located on the lower left side of the engine block. Potential Causes: Damaged Circuit 300
Damaged Connector C101
Improperly Installed Engine Compartment Harness
Malfunctioning Ignition Switch

Aug 26, 2011 | 2006 Chevrolet Trailblazer

1 Answer

My 93 cadillac seville blower motor was staying on .so i disconnected the conector to the motor under the hood. i found that there was battery voltage on connector. then i jumpered the battery to...

Hello, The power module controls the blower motor. It is located on top of the heater case under the hood towaeds the passenger side. When replacing the power module make sure the seperate ground wire is tight and that it is a good ground.

Sep 27, 2010 | 1995 Cadillac DeVille

1 Answer

Heater blower stopped working, it was intermittant for a while now does not work at all in any mode.

1. Check your fuse and/or relay for the blower motor. Unplug each one, inspect and replug it back in and recheck operation of the Blower Motor.
If that does does not fix the problem:
2. Locate the Blower Motor Resistor. It should be adjacent to Motor, and has 3-4 wires going into it.
The system works: Switches to Resistor to Motor.
Unplug the Resistor and check for voltage there. If there is voltage: Then the switches are good. If no voltage: the switches need to be checked.
3. Replug the resistor back in and disconnect the electrical connection/power going to the blower motor itself. Check for voltage coming from the resistor. Use the switches to change speeds and recheck each time for voltage. Go through the entire range of speeds on the switch. The voltage should fluctuate, increasing with each higher switch speed selected. If there is no voltage then the resistor is bad and needs to be replaced. If there is voltage and fluctuation with each speed, then the Blower Motor itself is bad and needs to be replaced.
4. Another (very different) way to check the Blower Motor is to take a verk long piece of heavy gauge insulated wire and connect one end of the wire to the positive side of the battery. Connect the other end or the wire to the Blower Motor. If the Blower Motor comes on, then it is not the Motor, but either a switch or resistor problem.
Let me know if this helped, or if you have additional questions, problems or information. Feel free to contact me at!

Jan 28, 2010 | 1996 Ford Explorer

2 Answers

1999 cadillac deville blower dont operate. What should the voltage be at the red wire and the gray wire or the black wire ? Iam assuming the red wire should be 12 volts, the gray wire should be variable...

red black and gray are just half the connections. Red is positive 12 volts coming from fuse of circuit breaker. The black wire is either the ground or the main hot wire going to the blower motor (3 pin connection only), and the gray wire (if is is small in size) is a variable voltage coming from the body control module requesting speed for the blower motor.The blower control module varies voltage on the main wire going to the blower motor, supposedly in accordance with the requested voltage from the body control module. Usually if all fuses are okay and present on the apprpriate wire of the blower control module, the a blower motor that will not run or stays running after the key is turned off is the fault of the blower control module. If the blower control module has failed the the cause must be determined (over amping blower motor) or else new blower control module may fail when powered up.Usually blower control modules have more than three wires. Usual connections are: B+ (battery voltage) GND (chassis or engine ground), two large wires going directly to blower motor (can be any color, but are usually 10 guage in size), and an optional wire that reports voltage level back to the body control module.

Jan 11, 2009 | 1999 Cadillac DeVille

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