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Discussion Starter #1 (Edited)
Hello everyone! One of the most recent projects I've worked on is replacing the backlight bulbs on the Climate Control module of my 2001 Jeep Grand Cherokee. Some of the bulbs that provide the backlight for the knobs and graphics burned out and didn't look too great at night.

There are two different kinds of Climate Control modules, the MTC (Manual Temperature Control) and the AZC (Automatic Zone Control) seen below:

MTC Control Module (6 bulbs = 4 backlight + 2 button bulbs):

AZC Control Module (13 bulbs = 10 backlight bulbs + 3 button bulbs*):



The MTC control unit has bulbs that can be easily removed and replaced but the AZC control module has bulbs that are soldered to the PCB board and require quite a bit more work to replace.
You can info on the bulbs here and here at WJJeeps.com.

The factory bulbs for the AZC module cost a lot more than buying a box of universal bulbs of the same size and voltage. WJJeeps.com specifies that the graphics bulbs have a number of 5013123AA and the knob bulbs have a number of 5013124AA.
I believe the latter to be incorrect however as images of the bulb look like the ones for the button bulbs on the MTC. You can find a pic here.
Also, WJJeeps states that there are 8 bulbs on the AZC for the graphics when there are actually 10...2 are hidden under the AC and Recirc buttons and light the graphics on those buttons.

*I cannot find any information on the button bulbs for the AZC. All I know is that they are also soldered to the PCB and are smaller in size compared to the graphics bulbs. If anyone has any info on these bulbs please let me know, I'd like to add that information here. These bulbs are hidden within the buttons and are only visible with the buttons removed. You can see the Rear Defrost Button bulb within the black shroud in the 2nd picture in Step 6 - FOR AZC.

This write up will go through the process of removing your MTC or AZC control module and replacing the bulbs with OEM (MTC) or OEM style (AZC) bulbs (All but the button bulbs).

Tools/Materials Needed:
For either Module:
-Plastic Pry Tool (plastic putty knife will work if its thick and strong)
-#2 Phillips screwdriver

For the MTC Module:
-Flathead screwdriver (Only needed if replacing Rear Defrost or AC button bulbs)
-4 PC74 bulbs for the backlight bulbs
-2 1-05013124AA bulbs for the Rear Defrost & A/C button bulbs.

For the AZC Module:
-Torx T-15 Screwdriver (Screwdriver with interchangeable bits may work but the shaft
of the driver must be thin. I'll show you why later) (WJJeeps says T-20 but I couldn't
get it to fit, have both on hand just in case)
-Soldering Iron with a good sharp tip (Adjustable Temperature is a plus)
-Electrical Solder
-Solder Wick
-Wire Cutters for trimming the new bulb leads
-Box of 10 Ecko 2162 Mini Indicator 12V bulbs for the backlight bulbs. Can be found
here at Amazon.*

*Another set of bulbs that should work are these CED Industries 7219 Bulbs here. Same voltage but seem to be smaller in size...probably comparable to the factory bulb size without the base.

I give thanks to the creator of the below youtube video for the recommendation on the Ecko bulbs

Bulb/Color Change Tips:
---The Climate Control face plates (for either MTC or AZC) have translucent areas that provide a way for light to pass thru the graphics (I know...I know...duh). These translucent areas are blue in color. The combination of the yellow light from the bulbs and blue color of the translucent areas provide the green light we see in our Grand Cherokees at night. If you want to see blue instead then consider changing to a bulb that provides whiter light. The exceptions are the temperature knob graphics that are true blue and red.
---You can switch to LEDs if you so desire if you want to change the color OR get longer life from your bulbs. However you MUST be sure they are 12V LEDs otherwise you will need to include resistors so they don't burn up. Here are some LEDs that would work because they come with resistors built in.


Let's begin!

Step 1: Disconnect the Negative Terminal Of Your Battery

Yes....you hear this all the time I get it....but when you skip this step and fry something you will wish you hadn't....just do it.

Step 2: Radio/Center Air Vent Bezel Removal

Using your plastic pry tool, get behind the bezel at the highlighted edges below and pry away from the dash to detach it:



Step 3: Ash Tray/Lower Dash Bezel Removal

Using your plastic pry tool again, get behind the bezel at the highlighted edges below and pry away from the dash to detach it:



Step 4: Remove Mounting Screws from the Climate Control Unit

Remove the 4 phillips screws from the climate control module. Two are at the top, and two at the bottom. The below picture shows the screw locations for the AZC module. The MTC will be very similar.



Step 5: Unplug Connections from the Climate Control Module

Once you have the 4 mounting screws removed, pull the module forward toward you and tilt the face down so you can see the connections on the back. BE GENTLE WITH ALL CONNECTIONS
The AZC module will have two wire harnesses running to the back.
The MTC module will have three connections, two electrical harnesses and 1 vacuum harness.

The electrical connections will have clips/locks that you will have to deal with so be patient and study the connection to figure out how to disengage it properly. The AZC connections have buttons to depress while pulling to unlock them from the control module as seen below. Mine were pretty tight and I had them rock them side to side a bit to get them to come out.

MTC Connections


AZC Connections


Step 6 - FOR MTC: Change your Bulbs and Reinstall all Components (MTC ONLY, go to Step 6 - AZC below for AZC)

Now it's the easy part! Looking at the back of your MTC module you will see 4 bulb sockets on the top and two at the bottom that do not protrude like the top ones do. See picture below.



The top ones can be removed by twisting them counter-clockwise until they unlock and come out. The bottom ones will come out the same way but you will need a flat head screwdriver to twist them. Proceed on removing them and replacing the ones that are burned out. Installation of everything is simply the reverse of the removal:
• Replace all bulbs or just the ones that need it.
• Reconnect the wiring harnesses and vacuum lines to the MTC Control Module
• TEST that everything lights up on the module correctly and the issue is fixed before finished reinstallation.
• If everything tests good...remount the module to the dash using the 4 screws (Do NOT over tighten)
• Install the Lower Dash Bezel and ash tray by aligning the clips with the holes and firmly pressing the bezel into the dash until both clips lock into place.
• Install the Upper Bezel by aligning the clips with the holes and firmly pressing the bezel into the dash until all clips lock into place.
• Reconnect your battery


Step 6 - FOR AZC: Opening the Module (AZC ONLY, go to Step 6 - MTC above for MTC)

Take your AZC module to your workbench or wherever you feel comfortable working on it and performing soldering tasks.

Looking at the back of your module there are 4 Torx T15 (Or T20) screws that need to be removed as seen in the picture below.



This is where using a screwdriver with interchangeable bits might not work because the bottom screws are sunk deep into the plastic casing and the amount of space available is not enough for the shaft of a typical multipurpose driver. Using an actual Torx screwdriver will make this easy but if you don't have one then you could use a flat head screwdriver with the right size tip that can fit within the Torx head...most likely a mini flat head from an electronics repair toolkit or eye glass repair kit. Use firm pressure on the flat head and increase torque until the screw turns. BE CAREFUL....you do not want to strip the screw. If you are having trouble with the flat head then take a break and go buy yourself a set of torx drivers or even just the one T15 (Or T20) driver.

After removing the 4 screws, turn the module around so the front faces you and set it on its back. Hold the module together while you do this so it doesn't come apart on you.

Pull off the two temperature control knobs....they will just slide off with enough force.
Pull off the large Blower and Mode knobs in the same way.

The front face plate will now lift right off the rest of the control module revealing the PCB you will be working on. See picture below.




Step 7 - Identify The Burned Out Bulbs

After the front face plate is off you can reconnect your module and reconnect your battery temporarily to test the bulbs and see which ones are burned out.
WARNING: The top PCB board WILL fall out if you let it. Keep a finger on it so it stays in place while you reconnect the module.

After your module is reconnected, reconnect your battery and turn on your parking lights...take note of which bulbs will need replacing. Here is what mine looked like. I had four burnt out bulbs:



Turn off your lights, disconnect your battery, disconnect your module, and go back to your workbench.


Step 8 - Remove the PCB

With your module back on the work bench unplug the two small wire harnesses seen below:



Each connector has an edge I could get my fingernails under. I gently lifted up on each side of each connector applying pressure back and forth and rocking it until they came out.

You can now remove the Top PCB from the module case. Pull the top of the PCB away from the case first and then up and out. You will see a 2nd PCB board underneath as seen in the picture below...but don't worry, we are not doing anything to this one. Put the module case with 2nd PCB to the side...we are focusing on the top PCB.

Here is the Top PCB removed:



Step 9 - Remove Burned Out Bulbs

Now we are getting to the nitty gritty. This is where we step away from the world of clips and screws and connectors and into the world of molten solder and silver drops of doom. Haha just kidding, it's really not that hard...but drops of hot molten solder do hurt....just FYI.

For each bulb that is burnt out you need to identify the two points of solder at the back of the PCB that connect the bulb to the PCB. You then need to heat each point while pulling on the bulb until the bulb is removed from the PCB.
*If your soldering iron has an adjustable temperature then choose the lowest temp that still melts the solder on the PCB in around a second. *

The solder points will cool and solidify very quickly so the method I used to remove each bulb went like this:
• Heat one point while pulling that side of the bulb away from the PCB
• When the one side of the bulb started coming away from the PCB, I switched points/sides.
• Heat the other point and pull the other side of the bulb until that side started coming away from the PCB.
• Switch again. I did this multiple times in succession until the bulb was completely separated from the PCB. This will also help prevent overheating of the PCB.

After the bulbs are removed inspect each solder point to see if any old solder is left. This where having a soldering iron with a sharp point is an absolute must....that sharp point will enable you to perform accurate work on small solder points. You want to remove the old solder from each point using the tip of your soldering iron.
First remove any current solder on the tip of your iron using the wick and then proceed on heating the little bit of solder left which then should stick to the tip of your iron. Remove the solder from your iron using solder wick or a tip cleaner and continue cleaning out the other points. If you have trouble getting the old solder to stick to your iron try using some solder wick on the old solder directly while you heat it.


Step 10 - Prep the New Bulbs

Before you solder the new bulbs on the PCB you want to cut the leads on each new bulb so that the length of the leads on the new bulbs is the same as the leads on the old bulbs. The Ecko bulbs are longer than the factory bulbs but the factory bulbs have a plastic base that adds to their length. The Ecko bulbs are also a bit larger in diameter but this won't hurt.
Trim the leads so both are the same length and have the same length as the factory bulbs. See the picture below.



After you trim the leads, apply a thin layer of solder to each lead. This cleans the leads so solder will attach well and make soldering the bulb to the PCB a bit easier. After you apply the solder, ensure that the leads will fit through the open solder points on the PCB. If they don't then you put too much solder on, remove some. You just want a very thin coat of solder over each lead.


Step 11 - Replace the Bulbs

After your bulbs are prepped it's time to solder them to the PCB. For each bulb you want to insert the leads thru the pair of open solder points (polarity doesn't matter with these bulbs) on the PCB where each bulb needs to be. You want the base of the bulb to be touching the PCB so the bulb doesn't move around once mounted. See Below



While holding the bulb in place and pressing it against the PCB apply some new solder to the tip of your iron and apply that solder to each point on the back of the PCB ensuring that each hole is filled with solder and the lead is completely surrounded. Also make sure that solder DOES NOT connect the two points...they must NOT be connected to each other. If they do connect just use the tip of your iron and/or the wick to correct the issue. When both points are complete give the solder 10 seconds to cool before you release the pressure on the bulb. Check your work.

Do the same thing for each bulb you need to replace taking breaks if you need to so you can maintain your level of focus.


Step 12 - Test Your New Bulbs

Once you are done soldering your new bulbs on the PCB it's time to test them to ensure everything is in working order BEFORE you reassemble everything.

Proceed on placing the PCB back into the module case. Make sure you slide the PCB underneath the two tabs on the left and right of the module case. I've highlighted them in the picture below.



Also be sure to feed the two wire harnesses from the lower PCB through the cut out in the upper PCB.

Reconnect those two wire harnesses.

Connect your module to your jeep, reconnect your battery, turn on your lights....are all the bulbs on and working?

Yes?
Fantastic! Proceed on safely removing your module from your jeep for the last time.

No?
Proceed on safely removing your module from your jeep and take another look at your work ensuring that no two solder points are connected to each other and that all solder points are filled with solder and the bulb leads are completely surrounded with solder. If all looks good then there is the possibility that one of the new bulbs was a dud. Proceed on replacing it with another. You can test the bulbs without powering them by using a volt/ohm meter with a continuity mode. Check that the there is continuity between the bulb's leads. You can also use your meter to test if power is getting to the bulb.

Here are all my new bulbs working:



Step 13 - Reassembly

Once all bulbs are working, proceed on reassembling your AZC Control module which is the reverse of disassembly:
• Place the upper PCB back into the module case ensuring the bottom of the PCB slides under the tabs seen in the picture in Step 12. Be sure to feed the lower PCB wiring through the cut out in the upper PCB.
• Reconnect the two wire harnesses to the PCB
• Place the face plate over the PCB and ensure it mates fully with the module case
• Replace the control knobs. Push them on firmly until they stop.
• Replace the 4 Torx T15 screws and tighten until they are firm. DO NOT over tighten
• Look at the module all the way around and ensure everything is seated correctly and knobs rotate freely.
• Reconnect the Control Module to the dash wiring harnesses
• Remount the Control Module in the dash using the 4 phillips screws. Tighten until firm, DO NOT over tighten
• Install the Lower Dash Bezel and ash tray by aligning the clips with the holes and firmly pressing the bezel into the dash until both clips lock into place.
• Install the Upper Bezel by aligning the clips with the holes and firmly pressing the bezel into the dash until all clips lock into place.
• Reconnect your battery

Here is my ACZ lit up at night after replacing the bulbs:



Thanks for reading folks! Please feel free to ask any questions and comment. Also let me know if something isn't clear or confusing and I'll work on improving it/get more info/get better pictures etc...

-Jeep Boy
 

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The bulbs under the buttons may be 2182. They are not as bright as 2162, but a smaller diameter bulb is a T-1.
8098 comes with short wire leads and a plastic base.
I have not used bulbs, so this is just my guess. I am replacing mine with 12v LEDs.
 
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