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Ask Greg A Your Own Question

Greg A
Greg A, Master Troubleshooter
Category: Chevy
Satisfied Customers: 6166
Experience:  Working with Electronics & Cars for 25+ Years
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in my 2000 chevy silverado the blower motor works on ...

Customer Question

in my 2000 chevy silverado the blower motor works on all setting except high
Submitted: 6 years ago.
Category: Chevy
Expert:  Greg A replied 6 years ago.

HiCustomer Thank you for asking your question on Just Answer.

Can you tell me if you have the Manual or Automatic system (automatic has a digital display that you would set the temperature on).

Also, can I assume you have AC too?

Thanks

Customer: replied 6 years ago.
Reply to Greg A's Post: manual
Expert:  Greg A replied 6 years ago.

OK. Then you have two possibilities.

1 - The relay on the blower motor resistor pack has failed, and the resistor pack will have to be replaced.

2 - The fuse that supplies power to the blower motor when the switch is set to High is bad (in the upper-right of the schematic).

I would check that fuse first (in the engine wiring harness junction block) and make sure power is making it to and from that fuse.

graphic

Please let me know what you find or if you need further instructions.

Take Care, Greg A.

Expert:  Greg A replied 6 years ago.

Hi again.

Here is a diagram of the Engine Wiring Junction Block.

graphic

I believe the fuse you will be looking for is # XXXXX (see table below).

Important:

Numbers shown are to reference position only - component not marked.

 

Fuse/Circuit Breaker

Rating

Description

STUD 1 Fuse #1

40A

Trailer Wiring / Automatic Level Control Compressor

ABS Fuse #2

60A

Brake Pressure Modulator Valve (Pump)

IGN A Fuse #3

40A

Starter Relay, Ignition Switch-IGN 1, TURN, SEO IGN Fuses

AIR Fuse #4

30A

Secondary Air Injection Reaction Pump

RAP Fuse #5

50A

Rap Relay, MIR/LOCK DR LOCK Fuses and SEATS Circuit Breaker

IGN B Fuse #6

50A

Ignition Switch-Rap Relay, Wiper/Washer and SEO ACCY Fuses

RAP 2 Fuse #7

50A

Power Window RF switch,Power Window RR Switch,Power Sunroof

STUD 2 Fuse #8

30A

Body Wiring Provisions, Trailer Wiring

TRL R TRN 9

10A

Trailer Turn and Stop

TRL L TRN Fuse #10

10A

Trailer Turn

INJ B Fuse #11

15A

Fuel Injectors 2, 4, 6, and 8, Ignition Coils, Engine Shutoff Solenoid and Sensor-Diesel

PARK LP Fuse #12

30A

Park Lamp Relay, Headlamp and Panel Dimmer Switch-Park Lamps

FRT HVAC Fuse #13

30A

Blower Motor (High Speed)

STOP LPS Fuse #14

20A

VEH STOP and CHMSL Fuses, Trailer Wiring (LH, RH Turn and Stop Lamp)

ECM 1 Fuse #15

10A

Vehicle Control Module (VCM)/Powertrain Control Module (PCM)-(from IGN 1 Relay)

CHMSL Fuse #16

10A

Center High Mounted Stop Lamp

VEH STOP Fuse #17

10A

Vehicle Stop Lamps

TRL B/U Fuse #19

10A

Trailer Backup Lamps

INJA Fuse #20

15A

Fuel Injectors 1, 3, 5, and 7, Ignition Coils, Glow Plug Module, Fuel Heat, Water in Fuel (WIF) Sensor, Wastegate Solenoid

RR HVAC Fuse #21

30A

Rear Heater,Rear Blower Relays

VEH B/U Fuse #22

15A

Vehicle Backup Lamps

ENG 1 Fuse #23

10A

Mass Air Flow (MAF) Sensor, Camshaft Position (CMP) Sensor, Evaporator Emission (EVAP) Canister Vent Valve, Evaporative Emission (EVAP) C Purge Valve

ETC Fuse #24

15A

Electronic Throttle Control (ETC)

IGN E Fuse #25

10A

A/C Compressor Clutch Relay, DRL Relay, Rear Defog Relay, Secondary Injection Reaction Pump Relay

B/U LP Fuse #26

25A

Backup Lamps, BTSI

ATC Fuse #27

20A

Automatic Transfer Case (ATC) Control Module, Encoder Motor

RTD Fuse #28

30A

Real Time Damping (RTD)

RR PRK Fuse #29

10A

RR Park Lamps

ECM B Fuse #30

20A

Fuel Pump Relay, Vehicle Control Module (VCM)/Powertrain Control Module (PCM)

O2 A Fuse #31

15A

Heated Oxygen Sensors

O2 B Fuse #32

15A

Heated Oxygen Sensors

LR PRK Fuse #33

10A

LR Park Lamps

RR DEFOG Fuse #34

30A

Rear Window Defogger

TRL PRK Fuse #35

15A

Trailer Park

PRIME #36

--

Fuel Pump Prime Port

RT HDLP Fuse #37

15A

RH Headlamps (Hi and Low)

HTD MIR Fuse #38

10A

Heated Outside Mirrors

LT HDLP Fuse #39

15A

LH Headlamps (Hi and Low)

A/C Fuse #40

10A

A/C Compressor Clutch

AUX PWR Fuse #41

20A

Auxiliary Power Outlets

SEO 2 Fuse #42

30A

Roof Beacon and Relay, Full Feature Seat - LH and RH

SEO 1 Fuse #43

15A

Roof Beacon Switch, Cellular Phone Wiring Provisions

DRL Fuse #44

10A

Daytime Running Lamps (DRL)

FOG LPS Fuse #45

15A

Fog Lamps

RADIO Fuse #46

15A

Radio and Instrument Cluster

CIGAR Fuse #47

15A

Data Link Connector, Cigar Lighter

RT TURN Fuse #48

10A

RH Turn Signals

ATSLC Fuse #49

10A

Automatic Transmission Shift Lock Control Solenoid

LT TURN Fuse #50

10A

LH Turn Signals

FR PRK Fuse #51

10A

Front Park Lamps

W/W Pump Fuse #52

15A

Windsheild Washer Pump

IGN C Fuse #53

20A

Ignition Switch, Crank, IGN 0 Fuses

RDO AMP Fuse #54

25A

Radio/Audio Systems Amplifier

HAZ LP Fuse #55

20A

Hazard Lamps

EXP LPS Fuse #56

10A

Not Used

HORN Fuse #57

15A

Horn/Horn Relay

CTSY LP Fuse #58

15A

Inadvertent Power Relay (Courtesy Lamps)

RR WPR Fuse #59

25A

RR Wiper Washer,RR Wiper Motor

TBC Fuse #60

10A

Body Control Module

Customer: replied 6 years ago.
i checked the fuse it is good and i replaced the blower motoer relay it clicks once when i switch from 4 to 5
Expert:  Greg A replied 6 years ago.
Is that the relay on the blower motor resistor pack?
Customer: replied 6 years ago.
yes
Expert:  Greg A replied 6 years ago.

Let me do a little checking. I thought the relay was "integrated" into the resistor pack.

But if it can be replaced, you will have to measure to make sure that the power is getting to the input of that relay, and is making to the output. If not, you could have a burned trace on the resistor assembly board.

Back soon, Greg A.

Customer: replied 6 years ago.
it is integrated it resistor is connects to the hardness fron the ac controls then go to the blower motor and has the resistor board that goes into the plastic "pipe" that goes from the blower to somewhere
Expert:  Greg A replied 6 years ago.

Hi again,

I believe the resistor pack should look something like this, where the relay is enclosed inside the "box" I have drawn below.

graphic

Is this what you have?

Thanks

Customer: replied 6 years ago.
yes
Expert:  Greg A replied 6 years ago.

OK. Well if you can hear that relay clicking, then you will actually have to test to see if the power is coming into that relay, from the fuse you said you checked. Then make sure that the power can make it to the output.

What I would do is probe Pin G (should be an orange wire) when the controls are set to High, and the ignition is turned on. You can use a multimeter set on the voltage scale, or a test light, to check for power on that pin.

Then check for power coming out of what should be a purple wire and going to the blower motor. You will need to have power there too. If the current is not making it through that path when the system is switched to High, then there has to be a connection problem with that relay.

Please let me know what you find, or if you need more help.

Take Care, Greg A.

Customer: replied 6 years ago.
ill check then get back with u in 3 hour if you r awake
Expert:  Greg A replied 6 years ago.

I am in West Coast time, so that shouldn't be a problem.

Just so you know, usually the Resistor modules are sold and replaced as one assembly. I checked on Rockauto.com and found that they cost about $25-$35.

On some of my older vehicles, I have gotten away with replacing relays on the resistor modules, but they don't seem to last very long. I don't think the "generic" relay I put in there could stand the higher current when the motor is on high.

Take Care, Greg A.

Customer: replied 6 years ago.
before i go i was going to tell you i bought my resistor from rockauto last week and put it on to day so i tell you later what happen with volt test
Expert:  Greg A replied 6 years ago.

Thanks for letting me know. You may have got a bad module there. It happens some times.

 

Customer: replied 6 years ago.
i tested the g pin and from the red wire same as purple i got 12 volts from both, could the motor be bad, even though that doesn't make since i would not work on high
Expert:  Greg A replied 6 years ago.

Hi again Tex. Sorry to get back to you so late, but I was out for a late supper with my wife.

It does sound kind of strange. I would think that if the motor runs on the lower speeds, it should run on the high speed setting.

Did you make the measurements on the motor side of the relay with everything still connected? If not, I would reconnect everything and "back-probe" the pin that leads to the motor (red or purple wire - the output side) and watch the voltage for changes between the high setting and the next lower setting that works. If you do that, please let me know what the two voltage readings are (assuming you have a voltmeter).

I would hate for you to replace the motor and then have the same results, but I suppose I have seen stranger things happen. It just doesn't make sense to me that the motor would run at all speeds except high, if the motor is bad.

Another thing you can try is applying power (and ground) directly to the motor connector pins. That would be the same as using the high setting through that relay.

Please let me know what you find.

Take Care, Greg A.

Customer: replied 6 years ago.
i tested and i got 12.6 volts on all settings so am officially stumped i stuck red prob on red wire an black on black and i switch through the settings and got 12.6 so i hope you can help somehow
Expert:  Greg A replied 6 years ago.

Next step is to apply power and ground directly to the motor. That means pull the connector to the motor loose, the apply power directly to the motor connector pins. The motor should spin a full speed.

This is starting to get a little baffling. The schmatic does not show that the ground is switched, and your measurements look correct. Strange.

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