Originally Posted by rayman0690

This applies to 2002-2006 Lancers and Lancer Evolutions. It applies to USDM (Left Side Drive) cars.

This thread is not for compressor failure or refrigerant leaks. It discusses how to fix a broken temperature control knob, as well as any binding that may have caused this temperature control knob to break or become very difficult to turn.

First off, you may have multiple problems with your HVAC system. It could be something very minor like a kinked/bent cable that moves the gears to something more serious like a binding blend door. I will explain the entire system and then hopefully you can discern what steps you need to take to fix your issue. If you follow it step-by-step then you will eventually have performed the TSB(s) that Mitsubishi has issued for this problem.

I have battled for the past 4 months with my 2003 Evo VIII’s HVAC system. I did a lot of research and through the use of this thread (https://www.evolutionm.net/forums/ev...n-problem.html) as well as the technical manual and the service bulletins issued; I was able to successfully repair my system in its entirety.



A Quick Background
Mitsubishi knows this is a problem. It affects the 2002-2003 Lancer, 2003 Lancer Evolution and the 2003 Outlander. However, I have seen many cars other than the above ones including the later model Evolutions that still suffer from these issues. They have issued TWO TSBs for this problem…but not a recall! The first is TSB-04-55-003 that was issued in March of 2004. The second is TSB-05-55-003 that was issued in December of 2005 that then changes its tune to say that the affected vehicles are 2002-and on Lancers and 2003-and on Outlanders. So there’s a revision for the revision. Awesome.

I have heard reports of people checking with their local dealerships about fixing the issue and some get it repaired under warranty. Although, at this time most of the cars that this effects are out of warranty. When I asked my dealer about a fix they quoted me a price of $1100 for parts and labor. Now that does include ALL of the steps I have listed below as well as all the parts. However, you can probably save yourself $700-800 and just do it yourself.



First Things First
I didn’t take tons of pictures and step-by-step shots as I was doing this. Once again, it was over a 4 month period of time. However, I will try and explain in lots of detail so you get a pretty accurate picture. I do have some pictures scattered throughout but not a step-by-step instruction on removing every screw and bolt.

There is a lot of information on the HVAC issue. Service bulletins and the technical manual are probably your best friend…which is why I have bundled all of the pertinent information into a .ZIP file. Within it are .PDF and some .JPG files that explain generally what needs to be done and also diagrams of how things come apart!

Archive of Informative Goodies Here!

When you download and unzip that file to your computer you will see these files:

• GR00004000-52A.pdf
• GR00004800-55.pdf
• HVAC 04 TSB.pdf
• HVAC 05 TSB.zip

The first two are from the Technical Service Manual for a 2003 Lancer Evolution. However, this information should still be nearly identical for all Lancers and years (2002-2006)

• …-52A.pdf is the interior page from the manual
• …-55.pdf is the HVAC section from the manual
• 04 TSB.pdf is the first service bulletin issued. It generally outlines what we need to do but doesn’t go into great detail
• 05 TSB.zip is a little more informative than the last one but doesn’t have any radical changes

Gathering Parts
You may not need all of the parts listed below but you may find you need one or all of them (depending upon what happened to your system)

• Heater air blend link and lever kit (set of revised gears) – 7801A110
• Blow motor housing filter (pollen filter, cabin air filter; for Lancer & Lancer Evolution) – MN185231
• Screw (2 required; for cabin air filter) – MF453032
• Heater Control Wire (air/mix wire) – MR979515
  There is a picture here
• Heater Blend Door (inside the white box; this kit also includes 10 screws and a foam seal [explained later]) - 7801A360
• Heater Panel Assembly (A/C ECU, HVAC Control Unit) – MN185138HA
  This part is actually the HVAC control unit, with knobs, wires, HVAC faceplate surround and HVAC stickers. Mitsubishi does not sell the HVAC control unit by itself. If you have broken your temperature control knob and don’t need all the other parts then you will probably have the best luck buying a used one on these forums. Otherwise you have to buy all the parts. This is due to the fact that Mitsubishi gets all the parts in a box and the above part number is for that box of parts.
• Heater Core Hoses – 7805A089 (The listed part number is for a 2003 Lancer Evolution. I suspect the hoses may be different from other cars...maybe. You'll need to double check this on your own car.

You can probably find the above parts used off another person who is parting out their car. Otherwise, I recommend using Mitsubishiparts.net and ordering what you need! That’s where I got everything except one part for my repair! They are much, much cheaper even with shipping than my local dealership was. Call and ask for Russell too, he will help get you what you need and can answer any detailed questions you have about parts. You can also go here to contact him on the forum... https://www.evolutionm.net/forums/mi...t-updates.html


The Tools

• Phillips Head Screwdrivers of varying length
• A Phillips Head Ratcheting (low-profile) Screwdriver (will help in some stages!)
• A flat head screwdriver (for prying and popping plastic pieces off)
• A ratchet with 10, 12 and 14mm sockets
• Two deep sockets of 12 and 14mm lengths
• Ratchet extensions (something that can be at least 9” – 12” in length)
• A short piece of breaker bar for your ratchet
• Large wire cutters or PVC pipe cutters to allow you to cut rubber hose (if necessary)
• Pliers (needle-nose and blunt)
• Utility knife (or a knife that can cut through ¼” plastic; a linoleum knife works well too)
• Flashlight or Sunlight
• Some lithium grease
• Ziploc Sandwich Bags or Small Containers (to put all your screws/bolts in)
• Sharpie (to label the containers/bags)
• Preferably something to protect your hands (Mechanix gloves) – you’ll be messing around some very sharp metal
• Band-Aids
• Lots of patience
• Time

Before We Start
This is going to take you awhile if you have to do all of these repairs. You should have alternate transportation and you should plan at least one weekend to a month to accomplish this repair. You have been warned.


Minor repairs first (And hope for the best!)
The first order of business is to figure out what exactly happened to your HVAC system. Did something bind on you, and you ended up snapping off that temperature knob on your HVAC control? Maybe you didn’t try and hulk it over and you let it be. Maybe you’re just reading about this to prevent it from happening. I will start from the minor repairs and work our way up to the very end.


Installing the Revised Gears (7801A110):
I recommend that EVERYONE do this to avoid having issues in the future. Get under your dash and see if you have the revised gears…if not, order them!

If you place yourself up under the driver’s side of the dash you will become cramped. Get used to it. The best way is to snake yourself in lying on your back with the seat moved all the way back and your feet on the ground. When lying in the floorboard you should be able to turn towards the radio and see a large white box that sits at the back of the firewall. This is the air mix box and where all the magic happens.
Right now we are only interested in the gears on the side of this mix box. If you look up you should see some gears as well as cables running to those gears. You need to take these gears off the side of the mix box and replace them with their revised counterparts. You accomplish this by taking your pliers and gently squeezing the tabs on the post on the gears (where the cable attaches). You should then be able to wiggle the cable free of the gears. After you have done this, you need to take your Philips head screwdriver and remove the one screw that holds each gear on (two screws total). This is where your low-profile screwdriver will come in handy! Use this here to avoid a lot of frustration. Once you have removed your old gears, set them aside and grab the revised set. Take a small amount of lithium grease and lube up the track as well as the slide where both gears fit together. (Check the TSB for pictures and the exact place to grease). Wipe away any excess grease. You will notice a small raised dot on the cog/gear that is still in the air mix box. You will also notice a cutout in one of the revised gears. You want to align the cutout on the gear so that the raised dot sits in the middle. This will ensure proper alignment and keep the blend door (inside the mix box) from binding. Put the gears on and screw them down and reattach your cable to the gears. Try and move your temperature control knob and see if it fixes your issue! If not, do not keep trying…you WILL break it! Read on.


Cabin Air Filter (MN185231 & MF453032):
I have included this step as the next item because I believe that even if you have installed the gears above (even if it does or does not fix your issue) this is still an important part to ensure damage doesn’t happen again or occur later on! If you have a 2003 Lancer, you probably don’t have this and it is a great idea to install one! If you have a later model Lancer, you MAY have this cabin air filter. But check just to be sure.

This is a very easy install.

Get in your passenger side and scoot the seat all the way back. Open your glove box and take everything out of it. On the left side of the glove box near the rear is a type of plastic slip. It is hard to find but stick your hand back there and try to pull up. It should pop off with minimal effort. Then, squeeze the sides of the glove box and it should release fairly easy. Let it fall gently to the floor and then pull straight off so you take the hooks off the bottom supports. Your glove box is now off. Move it aside.

You will be looking at your blower motor for your HVAC system. It is a large black item. Consult your TSB once again for illustrations and better information. At this point, it is easy to tell if you have a cabin air filter. If you see a white rectangle with two screws in it, you have the air filter. If not, you need to install it! For those of you that don’t you will see a plain black piece of plastic that is part of the blower motor. It should be a long rectangular piece with a screw hole in the top left and a screw hole in the bottom right. What you now have to do is take your knife and cut out the black plastic so you can slide your cabin air filter into that area. Once you have cut, look at your cabin air filter. It should have an arrow on the front that says Air Flow with an arrow. You want the air flow arrow to point downward. Install the filter and attach using the screws (MF453032) – remember you will need two screws!

This cabin air filter won’t fix any problem but is good preventative maintenance and should be changed every 10,000-30,000 miles depending upon your environment. Mitsubishi lists it as regular vehicle maintenance. I also advise checking it between every season and knocking loose dirt out. You may also notice that now your car smells better or stays cleaner on the inside! (I live in Alabama so we have lots of pollen at times and my interior stays a lot cleaner now)


Kinked/Bent Heater Control Wire (MR979515):
This one should be pretty obvious after you’ve gotten under your dash to inspect the gears and put in the revised ones. I’ve heard of people that had their control wire bend that caused the temperature control knob to be very obstinate. It will be a bent wire and you can just replace it pretty easily. You’ll have to get under the dash and remove the wire from the gears using your needle nose pliers. Then, sit in your driver’s seat like normal and remove the knobs from your HVAC control. Once those are off, carefully take your flathead screwdriver and pop the HVAC surround off. Remove your radio. Next you will see your HVAC control unit. On the left side should be the other end of the wire for temperature control. Carefully take your needle nose pliers and remove the cable from the control unit in the same manner that you removed the cable from the gears on the side of the air mix box. Then take your new cable and attach it to the HVAC control unit FIRST. Route it towards the left side of your mix box. Then, put yourself back in your floorboard and reattach the new cable to the gears. If you had a bent cable, this should fix your problem. If you haven’t already done so, please put in the revised gears while you’re at it! Check the temperature control knob for any signs of binding. If you feel a difficulty in turning, stop! Read on.





Now, maybe you’ve done the above fixes or whatever was damaged on your system but you also snapped off the temperature control knob. You didn’t understand why it wasn’t moving and so you Hulk’d it a little until it broke. Good job. Don’t feel bad though. I did it along with many other people. Well, you need to either order the entire kit from Mitsubishi (MN185138HA) or get the HVAC Control Unit from someone on this forum. Then you will need to swap parts from your old control unit to your new one. I recommend you clean the unit (if you get it used) and re-grease everything. Wipe away excess grease. You should then be able to move all your control cables to the new control unit and hook everything back up. Hopefully you have a completely repaired system then. Check for any signs of a hard to turn knob. This means binding. Don’t Hulk it over again unless you like to repeat things and lessen your pocketbook. Read on.



Now For the Hard Stuff...

Alright, so you’ve done all of the above or whatever you found out was damaged and your control knob still doesn’t turn with ease. Well, I am sorry but you are in the same boat I was in. Your blend door that is INSIDE the white air mix box is binding and not moving properly. This means tearing down the dashboard and center console. I will break this section into three parts. The first is everything you have to do inside the engine bay. The second is tearing apart the interior all the way down to removing the air mix box. The third is the repair of the air mix box and mounting back in the car. After that it’s reassembly. You should be able to do that yourself. If you need help, just holler.

I don’t mean to be the bearer of bad news but this is a major undertaking. This is why the dealer wants $1100 to fix this problem. The time and parts that it takes to do all this can rack up quite a bill. There are some people that have claimed to be able to repair it with some workarounds. I will explain that when we arrive at that point. However, I am going to explain the process that the TSB and dealership perform. It makes things quicker and easier in the long run rather than struggling with the workaround.
I will quickly explain the process in very broad terms and then explain in detail. That way you can decide whether or not you want to begin this project.


Summary:

Basically, you need to pop the hood. Get under the car and drain the radiator. I used the lower radiator hose. Then, remove the strut tower bar to give yourself some room. Next, the heater core hoses need to be detached. I had to cut mine off. Then, have a shop or remove the refrigerant yourself from the A/C system. Once you have freed the lines from the back of the evaporator you are done in the engine bay.

Next, take all interior pieces out. Remove the armrest piece, the shifter area. The kickpanels. The glovebox. The HVAC surround. The radio. The plastic pieces around the steering column. The instrument cluster. Everything else I missed so far. Unbolt the main dash piece (big black thing) from the front crossmember. Unbolt the steering column and rest it in the driver’s seat. Pull out the entire dash piece and set aside. Unbolt the front crossmember. Pull it out and down so you can start to remove the blower motor and cowl and ducting on the passenger side of the car. Remove all that junk. Unbolt the white air mix box. Maneuver the air mix box out of the passenger’s side of the car.

Now, tear apart the air mix box by breaking all the white tabs off. Replace the blend door in the box with the revised part. Clean everything. Reassemble the box. Put the box back into the car. Bolt everything back up.




Whew...Conclusion
Sound like enough work? It is.

I will add the final section sometime very soon!