2004 jeep liberty heater fan only works on high

I have a 2004 Jeep Liberty and the blower motor fan for the heat and air conditioning over time has gotten weaker and weaker to the point of setting number one not even working anymore. Over time, settings 1-3 will stop working and only 4 will work. Thanks to comments from Slav below, this is due to the full fan setting bypassing the resistor. I did some internet searching and found that this is a very common problem, but I couldn’t find very good instructions. Yes, there were step-by-step guides, but none answered all my questions. Here is my own attempt at helping you to make this job easy. (Click on any image for a larger resolution version.)

I had the dealership look up the part number — for my 2004 Liberty it is 5139719AA, although it is best to have them check fresh if you are going to tackle this project. If you decide you want to assume I’m right, here it is on Amazon.com.

Here are the tools I used: 2 small flat head screwdrivers, 8MM or 5/16″ socket (1/4″ drive), 1/4″ drive ratchet, 1/4″ drive long extension or a 1/4″ socket driver,  flashlight; optional & preferable: this looks like it would be the perfect tool for this job, a 1/4″ universal joint adapter.

Before starting, forums that I read insisted that you remove the negative wire from the battery to prevent airbag deployment. I was skeptical of this, but to nervous to risk it. Just do it.

1. Empty and remove the glove box. This is actually really simple. Open the door until it won’t open anymore. Look on the left and right for this large clip:

Push the clips toward each other and open the glovebox further:

Once you open the glovebox far enough, you can slide the whole thing to the right and remove it:

(I didn’t figure this out until I was done, so my subsequent pictures won’t reflect removing the glovebox door.)

2. Some might say to remove the wiring harness now, but I had a lot of trouble with that, so I took the resistor out, then worked on removing the wiring harness. This is when I first used my socket driver to remove the top screw:

3. For the bottom screw, I tried using my socket driver, but it was too much of an angle to bite:

This is where you can use a flexible or universal tool or a ratchet, like I did:

Thankfully I was able to hold on to the screws. If you drop one, I’m not sure how hard it is to get back.

4. Then I pulled the resistor out:

5. It took me a long time to figure this out: you must pull out the red clip lock in order to allow the black lever to release the wiring harness. Prying the red lock didn’t work, so I ended up needing to use a small screwdriver to push up on the little locking piece in the back:

Here’s what it looked like when it released:

At that point, push down on the black lever to release the wiring harness:

6. The rest is just going in reverse now, you can either put the harness on now or later; I chose now so I could see what I was doing.

Here is the old resistor. It has either worn out or made with very poor quality control:

PLEASE comment if there is a better way to do something that I didn’t figure out!! Also, let me know if this was helpful.

Why does my fan blower only work on high?

Why is my blower motor only work on Max?

What are the signs of a blower motor resistor going out?