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89 Gmc sierra no blower. Fuse good. No power to temp

Customer Question
89 Gmc sierra no...

89 Gmc sierra no blower. Fuse good. No power to temp actuator. Yes: power to A/c clutch relay,blower 1 and 2 relays. No power to wire to blower. Blower tested by run directly off battery; blower runs. What to do?

Mechanic's Assistant: Is the power loss consistent, or does it fluctuate?

Consistent no power to wire to blower.

Mechanic's Assistant: Are you fixing your Sierra yourself? What have you tried so far?

Yes, so far. Did try replacement dash control unit. No dif.

Submitted: 8 months ago.Category: GMC
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Answered in 56 minutes by:
9/18/2017
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago
KALAMYKID
KALAMYKID, Shop owner, tech
Category: GMC
Satisfied Customers: 5,229
Experience: HAVE OWNED MY OWN SHOP FOR OVER THREE YEARS. I HAVE THE TOOLS AND SOFTWARE TO ANSWERE ALMOST ANY QUESTION CORECTLY.
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Does the blower work on high?

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Customer reply replied 8 months ago
Blower does not work from control on dash, only if wired directly to battery or fusebox (bypass). It sounds like it is working at high.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Do you have a digital volt meter and a test light so we can test the system to see what is going on?

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Customer reply replied 8 months ago
test light only.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Can you get a digital volt meter from a friend?

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Customer reply replied 8 months ago
I'll see what I can come up with.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Thank you. There are a few test that you will need to know the exact voltages so we can see what is wrong with the system.

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Customer reply replied 8 months ago
I've got Autocraft digital multimeter.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

What size engine does your truck have and is it a 4X4?

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Customer reply replied 8 months ago
350. Yes, 4X4.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Do you know where the blower motor resister , high fan relay, as well as the low fan relays are?

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GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

If you need I can post a diagram of there locations.

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Customer reply replied 8 months ago
Have replaced blower motor resister. I believe low blower relay is on left side, high blower relay is on right side (a/c clutch relay in middle) behind glove box.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

The ac relay should be on the left. the low in the center and the high on the right. What I need you to do is unplug all 4 of these so you can move the wire harness out a little bit so you can test the wires in the plugs. The first thing I need you to do is with the ignition switch in the run position see what the voltages are for the brown wires to all three of the relays, as well as the dark green wires in the high relay and ac relay, and the light blue for the low relay.

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Customer reply replied 8 months ago
will test.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Let me know what the voltages are for each wire please.

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Customer reply replied 8 months ago
yep.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Thank you.

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Customer reply replied 8 months ago
results/volts
relays AC Low Hi
brown 12.12 12.12 12.12
dark green 0 0
light blue .41
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Did you have the ignition switch in the run position?

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Customer reply replied 8 months ago
it was in run position. radio was on, etc.
Customer reply replied 8 months ago
not lock off. not acc. but in run/on position.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Check the dark green wires with the white strip again but this time turn the ac on max ac, and the fan switch on high please. Make sure to check all 3 relays.

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Customer reply replied 8 months ago
0k
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

TY

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Customer reply replied 8 months ago
ac on max ac, fan on hi. All three relays green/ white stripe, green---0.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Does the dark blue wire with a white strip at the ac compressor relay have power with the switches on?

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Customer reply replied 8 months ago
dark blue/white strip @ ac relay ---- .39
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Do you have the heat/ac controls where you can get tot he plug on the back side of it?

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Customer reply replied 8 months ago
I have been using the old controller for all tests. have gotten another of same design.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

with the ignition switch in the run position, what is the voltage at the red wires on the controller plug?

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Customer reply replied 8 months ago
ign sw run. voltage at red wires ---0.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Look out on the fire wall under the hood. There is a bus bar with 4-5 studs on it. Thee should also be at least two red wires on it as well. Check the voltages of all the wires on the bus bar please and see what the voltages are.

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Customer reply replied 8 months ago
driver or passenger side?
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

It can be on either side. It will be a black plastic base, with 4-5 studs coming off of it, and will bolt to the fire wall. Most often it is on the passenger side.

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Customer reply replied 8 months ago
k
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

ty

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Customer reply replied 8 months ago
ignition switch run/on or off/lock?
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Run please.

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Customer reply replied 8 months ago
12.15 across all five posts, including red.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Can you send me a pic of the bus bar so I can see all of the wires attached to it?

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Customer reply replied 8 months ago
ok.
Customer reply replied 8 months ago
where/how to send it?
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

You should have an upload button in your tool bar for this chat window. Type me a message, hit the up load button, a new window will open up. Hit the chose file button and go tot he pic in your file folder where you saved the pic. Then hit the upload button in the pop up window. The pop up window will close and bring you back to the chat window. Hit the send button and the message and pic will both be posted.

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Customer reply replied 8 months ago
sent picture to***@******.***. needed to be resized, I think, so unable to send it .
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Go to this link and follow the directions to post the file here so i can see it please. http://ww2.justanswer.com/help/how-do-i-send-photo-or-file-expert-0

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Customer reply replied 8 months ago
Trying to send (according to instructions). Not finding "reply to expert" button. Will probably chat to admin.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

The "reply to expert" button, is the button you hit when you send me a message.

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Customer reply replied 8 months ago
duh.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

You hit the button every time you send me a message. I am sorry I do not see what the problem is.

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Customer reply replied 8 months ago
I have been able to upload and send photo to customer support via***@******.*** but not through the means you recommended. Error message came up each time I tried to attach it.
GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

Sending to customer support will not get them sent to me. What does the error message say?

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GMC Mechanic: KALAMYKID, Shop owner, tech replied 8 months ago

I just got a good surprise. Customer support just sent me your pic. You have fuseible link wires connected to this bus bar. If you look at the wires there is a plastic cylinder around the wires about 5 inches from the lug bolted tot he bus bar. I can not see clearly the color of the wires past the plastic cylinders. Are any of them red? If so check and see if you have 12 volts to the red wire past the plastic cylinder please. If you do not then you will need to install a new fuse link wire. Now the fun part. We have to find out why the link blew. Has the fan been making any kind of noises lately?

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