Knocking in the blower motor

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

5x10

Member
Joined
May 3, 2021
Posts
74
Reaction score
194
Ever since I replaced my motor relay, I have a knock coming from the blower motor

i thiught at first that I hadn’t mounted it right, but it’s mounted correctly
i can feel the knock in the plug coming off the side of the motor

anyone know what this is from?
im thinking it’s something in the motor itself
 

Fless

Staff member
Super Moderator
Joined
Apr 2, 2017
Posts
12,143
Reaction score
24,753
Location
Elev 5,280
Moved you here since this is an Interior issue.

Remove the blower motor and check for blockage or miscellaneous material in the heater cavity. Then run the blower outside of the cavity to see if you can determine that it's coming from the motor. The blower cage might be out of balance.
 

OR VietVet

Multnomah Falls
Supporting Member
Military
Joined
Oct 8, 2014
Posts
20,967
Reaction score
37,401
Location
Willamette Valley
Yes, blower cage or something in there. Could be the armature hitting in there. You replaced the motor relay, why? How long had it all sat no working before the relay? Good to run it outside the housing for a close inspection.
 

strutaeng

Full Access Member
Joined
Aug 10, 2023
Posts
1,270
Reaction score
2,752
Location
Dallas, Texas
Ever since I replaced my motor relay, I have a knock coming from the blower motor

i thiught at first that I hadn’t mounted it right, but it’s mounted correctly
i can feel the knock in the plug coming off the side of the motor

anyone know what this is from?
im thinking it’s something in the motor itself
Yes! I had this exact same issue on my 06 Suburban with the automatic control. Replaced the blower motor resistor (the only one that seemed to be a direct "plug and play" was from Amazon) and motor from RockAuto. I thought it was the motor, until I swapped another known good motor and same thumping sound! It sounds like something is loose or something like that.

I went back and the Amazon one and some reviews were saying this. I found a Four Seasons blower motor resistor that worked, I just had to cut off the old connector and splice the new one, but the instructions were very clear.

Problem solved!

I can provide part numbers if you want. The Amazon one was like $30-ish IIRC. No real name brand, made in China.

The Four Seasons was like $90 from RockAuto, assembled in the USA.
 
OP
OP
5

5x10

Member
Joined
May 3, 2021
Posts
74
Reaction score
194
Yes! I had this exact same issue on my 06 Suburban with the automatic control. Replaced the blower motor resistor (the only one that seemed to be a direct "plug and play" was from Amazon) and motor from RockAuto. I thought it was the motor, until I swapped another known good motor and same thumping sound! It sounds like something is loose or something like that.

I went back and the Amazon one and some reviews were saying this. I found a Four Seasons blower motor resistor that worked, I just had to cut off the old connector and splice the new one, but the instructions were very clear.

Problem solved!

I can provide part numbers if you want. The Amazon one was like $30-ish IIRC. No real name brand, made in China.

The Four Seasons was like $90 from RockAuto, assembled in the USA.
Got it, I’ll try another resistor

ive taken the motor out of the mount and held it in my hand , and it still has the knocking, coming from the connector that attaches

it’s almost like the other side of the plug is interfering with the motor


edit, after some more research, the blower might be bad too, as the new resistor did Seem to open and even higher fan speed, but shortly after, went back to what I had been used to and didn’t have the higher speed
 
Last edited:
OP
OP
5

5x10

Member
Joined
May 3, 2021
Posts
74
Reaction score
194
Got my blower/resistor kit in from rock auto
but

they are wired differently

my current resistor has a wiire coming to it and then a wire out of the resistor to the blower

rhe Replacement resistor only had a wire in, not one going out to motor
Not sure which one is stock

i need to get back under there and see if they clipped other wires(that led to the motor directly)

i did plug in the new motor and it seemed to have the same issue as my old motor, almost like it’s not a consistent Feed of power
 

strutaeng

Full Access Member
Joined
Aug 10, 2023
Posts
1,270
Reaction score
2,752
Location
Dallas, Texas
My resistor was Four Seasons #JB2079. It had a black ground, red power and a purple wire. Those got spliced into the harness from under the dash, which had the same colors. Be careful with the red wire, because it's powered even with key off, and comes from one of the huge fuses under the hood fuseblock.

The motor connector goes into the resistor.
 
OP
OP
5

5x10

Member
Joined
May 3, 2021
Posts
74
Reaction score
194
My resistor was Four Seasons #JB2079. It had a black ground, red power and a purple wire. Those got spliced into the harness from under the dash, which had the same colors. Be careful with the red wire, because it's powered even with key off, and comes from one of the huge fuses under the hood fuseblock.

The motor connector goes into the resistor.
Did yours have a wire coming from the resistor to the motor?

current

and replacement below
 

Attachments

  • 45F31558-6CDD-4B3A-B8F7-6470B05C37B4.jpeg
    45F31558-6CDD-4B3A-B8F7-6470B05C37B4.jpeg
    241.6 KB · Views: 2
  • 2E6E55C5-77A1-488B-9180-328D9C722F4F.jpeg
    2E6E55C5-77A1-488B-9180-328D9C722F4F.jpeg
    254.5 KB · Views: 2
Last edited:

strutaeng

Full Access Member
Joined
Aug 10, 2023
Posts
1,270
Reaction score
2,752
Location
Dallas, Texas
Did yours have a wire coming from the resistor to the motor?

current

and replacement below
Yes. Mine looked just like yours.

The new resistor actually has a female plug for the motor connector (I also had replaced the motor a few months ago with TYC 700164).
 
OP
OP
5

5x10

Member
Joined
May 3, 2021
Posts
74
Reaction score
194
Yes. Mine looked just like yours.

The new resistor actually has a female plug for the motor connector (I also had replaced the motor a few months ago with TYC 700164).
Sorry, I’m a little slow

currently, harness to resistor, which then has a wire to motor

what’s the new order? I see a female port in the resistor(5 prong) and the blower motor (which has a 2npromg connection)
 

Forum statistics

Threads
132,713
Posts
1,873,068
Members
97,536
Latest member
BigBodyBurban
Top