Knocking Under Dash

10

Asked by Apr 18, 2016 at 09:25 AM about the 2003 Chevrolet TrailBlazer Entended LT 4WD

Question type: Maintenance & Repair

My truck recently wouldn't start. My husband found that the battery
connection was loose. As soon as he fixed it a loud knocking started from
under the dash. It happens everytime I start the truck and lasts for about a
minute. What could it be? Thanks!

15 Answers

570

That sounds like your fan motor! Does the noise under the dash go away after about a minute?

1 out of 1 people think this is helpful.
42,815

Check the oil in the engine. May be low on oil, or you may just have a knock until oil pressure builds up.

570

My dads truck does the same thing. It knocks for about a minute an goes away! It's the Fan Motor! Go to the passenger side of the car open the door an listen up underneath the dash right under the glove box an let me know if that's where the Noise is coming from?

10

I don't believe it is the oil. It was just changed a few weeks ago and the knocking is not under the hood. Yes, the knocking stops after about a minute. It is in the middle of the dash, not on a specific side.

1 out of 1 people think this is helpful.
570

The thumping knocking noise is your Fan Motor! When you turn the Engine off does the Thumping Knocking Noise happen?

1 out of 1 people think this is helpful.
570

New Fan Motor will fix that Problem!

10

It doesn't knock when I turn off the engine. How do I get to the fan motor? Will I need to buy other parts? Thanks!!

10

Just trying to look up the part on ebay motors and there are several options. There is a blower motor heater fan or an a/c heater fan blower motor resistor. Which do you think I'd need?

570

Call your local parts stores an get a quote on your Fan Motor!

1 out of 1 people think this is helpful.
570

Blower motor an fan motor are the same thing

42,815

As Fiemfam7 is saying, there looks like there is two blower motors. One blows for the front and one blows for the rear.

570

Ok, your vehicle has 1 blower motor! That resistor is just a switch! You need a Blower motor for your heat, an AC.

570

Flemfam7, go to YouTube an type in 2003 Chevy trailblazer blower motor! It will show you how to fix your problem. I just searched it for you.

42,815

You guys know that there just may be some debris, or an alignment issue that is making the squire cage to hit or rub against. I would just take out the blower motors and look to see what the squire cage is hitting. If it was the motor itself it would have started to squeal first.

42,815

Squirrel Cage....

Your Answer

Add photo

Related Questions

TrailBlazer

Looking for a Used TrailBlazer in your area?

CarGurus has 5,120 nationwide TrailBlazer listings starting at $900.

ZIP:

Search Chevrolet TrailBlazer Questions

UK Questions

Are you a UK consumer? CarGurus now has a discussion forum in the UK.

Chevrolet TrailBlazer Experts

#1 Tom Demyan
Tom Demyan
Reputation 740
#2 bigdogracer
bigdogracer
Reputation 580
#3 dandyoun
dandyoun
Reputation 550
View All

Related Models For Sale

Used Chevrolet Tahoe
870 Great Deals out of 27,801 listings starting at $1,700
Used Jeep Grand Cherokee
911 Great Deals out of 66,035 listings starting at $300
Used GMC Envoy
42 Great Deals out of 2,215 listings starting at $2,500
Used Chevrolet TrailBlazer EXT
7 Great Deals out of 1,210 listings starting at $2,490
Used Chevrolet Silverado 1500
2,583 Great Deals out of 151,334 listings starting at $1,500
Used Ford Explorer
1,113 Great Deals out of 71,404 listings starting at $799
Used Chevrolet Impala
896 Great Deals out of 35,016 listings starting at $1,700
Used Chevrolet Blazer
1,282 listings starting at $2,000
Used Chevrolet Camaro
437 Great Deals out of 40,552 listings starting at $3,500
Used Dodge Durango
373 Great Deals out of 23,068 listings starting at $1,300
Used Ford F-150
3,010 Great Deals out of 207,475 listings starting at $1,200

Used Cars For Sale

2009 Chevrolet TrailBlazer For Sale
3 Great Deals out of 129 listings starting at $2,700
2008 Chevrolet TrailBlazer For Sale
34 Great Deals out of 719 listings starting at $1,500
2007 Chevrolet TrailBlazer For Sale
25 Great Deals out of 867 listings starting at $1,600
2006 Chevrolet TrailBlazer For Sale
24 Great Deals out of 856 listings starting at $1,700
2005 Chevrolet TrailBlazer For Sale
7 Great Deals out of 749 listings starting at $2,900