Mechanics

HEATER BLOWER RESISTER

1998 GMC Sierra

Heater problem
1998 GMC Sierra V8 Four Wheel Drive Automatic

Hello I am sending anouther request on my vehicle
I have only the high setting on the fan motor

I have replaced the air actuator the heater relay the
control pannel on dash and the heater blower resitor as requested by you guys,

up until I replaced the heater relay I couldnt controll the temp it was on high always.

what next? I am so frustrated with this now.
There are two wires going into the motor one is purple and the other is black test light works on the purple on high only tried it on lowest settring 1st
I see 2 yellow wires in a harness thas is connected to something on the fire wall but no others

after looking further I found the yellow wire going into the resistor and on low it has no power going to it
Avatar
Adubber
January 15, 2010.




[/quote:fda5d37c28]

Hi,

I ran a power line from the battery terminal to the yellow wire going into the resistor and the blower run on low, I did the same with the brown and it runs the fan on med and on blue it runs on med high
the high comes on if you turn it to high before starting the vehicle
i9f you have it on any other setting and start the vehicle it don't but will turn on after a few seconds or minutes no pattern.
I tested the 25A heater fuse and its good I found a aircond- relay in the fuse box under the hood and replaced it but that didn't change
I noticed that the air cond- don't come on at first when you push the button and after a while the light on the panel turns on.

From: "forum@2carpros.com" <forum@2carpros.com>
Sent: Sun, January 17, 2010 1:56:14 AM
Subject: Topic Reply Notification - 1998 GMC Sierra heater blower resister

Hello,

You are receiving this email because there is a reply to your question, "1998 GMC Sierra heater blower resister" at Auto Repair Car Questions.

To view and follow-up on the reply to your question, please click on the following link, http://www.2carpros.com/forum/viewtopic.php?p=772779#772779

Sincerely,

Bob, Ken and all of the 2CarPros team.

Tiny
Adubber
Jan 18, 2010.
[/quote:f708383860]

Hi,

I ran a power line from the battery terminal to the yellow wire going into the resistor and the blower run on low, I did the same with the brown and it runs the fan on med and on blue it runs on med high
the high comes on if you turn it to high before starting the vehicle
i9f you have it on any other setting and start the vehicle it don't but will turn on after a few seconds or minutes no pattern.
I tested the 25A heater fuse and its good I found a aircond- relay in the fuse box under the hood and replaced it but that didn't change
I noticed that the air cond- don't come on at first when you push the button and after a while the light on the panel turns on.

From: "forum@2carpros.com" <forum@2carpros.com>
Sent: Sun, January 17, 2010 1:56:14 AM
Subject: Topic Reply Notification - 1998 GMC Sierra heater blower resister

Hello,

You are receiving this email because there is a reply to your question, "1998 GMC Sierra heater blower resister" at Auto Repair Car Questions.

To view and follow-up on the reply to your question, please click on the following link, http://www.2carpros.com/forum/viewtopic.php?p=772779#772779

Sincerely,

Bob, Ken and all of the 2CarPros team.

Tiny
Adubber
Jan 18, 2010.
Sorry for the delay in replying.

Just to be sure we are on the right track with the correct model, the circuit I have posted is for the 4.3 L engine. If it is not correct, please let me know.

From the last diagnosis, we are getting somewhere. You have a power supply fault and we are getting near to our destination.

The blower motor and resistor are perfectly good.

Power is not coming out of the HVAC control unit and you would need to test if power is available at the speed control switch. Test the brown wire for battery voltage with ignition switch turned ON.

If power is available and no voltage is available at the Yellow, Tan and Light Blue wire when speed is turned to low, M1 and M2 respectively, the control switch is faulty.

KHLow2008
Jan 19, 2010.
Ok,
I will do that and let you know

You did mention the switch earlier and I went to baxter and purchased one and installed it
this didn't help the issue.

Tiny
Adubber
Jan 19, 2010.
You can test the switch for continuity according to the various speed mode.

Most important wire to test would be the power supply.

Was the switch replaced of the correct type?

KHLow2008
Jan 19, 2010.
Yes I have also relaced the hvac control unit on the dash

Tiny
Adubber
Jan 19, 2010.
If you have power on the brown wire coming from the heater 25amp fuse when key is On and when you switch to low the yellow wire should have power-Is this happening if not were right back with HVAC control module. Now if yellow has power, blower motor should come On-if not-check and test the ground pointG201 at right side of dash. Get back with us
AD

Tiny
Rasmataz
Jan 21, 2010.

AD