Auto Max AC Mod

Since moving from my 03 taco to my 13 taco I cant seem to get into the habit of not turning the temp control knob all the way to the left when I want some cold air. The problem with this is, as many of you know, is that when you turn the knob all of the way to the left, it turns on the MAX A/C "feature" which turns on recirc and the A/C. While you can turn the recirc off in this mode, the A/C can not be shut off until you turn the knob off of the MAX A/C setting. I know some of you are asking "why would you turn the knob all the way to cold and not want the A/C on?" Well short answer, I almost never use recirc due to the increased noise and lack of fresh air. Also, sometimes I just want the coolest outside air and don't want to run the A/C. Perhaps its habit from the 03 Taco days when running the A/C would quite noticeably reduce available HP, maybe have a problem with the truck making decisions for me. I dunno, whatever, I'm the driver, and I decide when things happen.

Thanks to fohlkmann for the write up on Disabling the A/C-Defrost link. It helped me while doing this mod. Fohlkmann's mod can be found here:

http://www.tacomaworld.com/forum/2nd-gen-tacomas/7160-c-defrost-8.html#post2395617

For a more mechanical version of this mod you can try CtTaco's version here:

http://www.tacomaworld.com/forum/2nd-gen-tacomas/125550-my-max-ac-bypass-writeup.html

The only issue I found with CtTaco's mod was that the air mix damper DOES move between the last blue block and MAX A/C positions on the temp selector, meaning you are still getting a very small amount of warm air mixed into your cold air. The only time the air mix damper is in the cold only position is when the temp selector knob is turned all the way to MAX A/C.

Ok, on with the mod. Step one is to locate the air mix damper servo connector. It is directly underneath the glove box to the left hand side. You do not have to remove the glove box to get to this connector however I found it was easier to fit with the glove box removed.


In this connector there are four wires, white/blk, red/wht, brown/wht, pink. The brown wire carries voltages to the A/C Amplifier ranging from approx. 0v to 12v depending on the position of the temp selection knob. 12v being hot, 0v cold. If the A/C Amplifier receives a 0v signal on this wire it turns on the A/C and closes the damper. What we are doing is simply telling the A/C amplifier that the temp selector knob is turned all the way to warm. We will do this by applying 12v to the brown by splicing it to the pink wire. (don't worry, the A/C amplifier only uses this brown wire to activate MAX A/C mode. Any adjustment to this wire does not affect how your HVAC system controls the temperature, everything still works properly.)

Here's what the connector looks like and the color order:


Step two, Disconnect the connector and remove the white cover from the connector. This can easily be done using a small screwdriver. You wil also need to untape and remove the plastic loom covering the wires.


Step three, the brown wire needs to be removed (or cut, if you cant get it) from the connector. I used a small nail inserted into the T shaped hole in the front of the connector to release the pin.


Step four, I lined the brown/wht wire up with the pink wire and cut both of them simultaneously to be sure the lengths coming from under the dash were the same.


Step five, strip both ends of the pink wire and the remaining brown/wht wire heading under the dash. (the other end of the brown wire which used to be going to the connector should now be loose and not connected to anything.)

After stripping the wires, take the brown/wht wire and the pink wire going under the dash, twist them together, and crimp them into one end of a butt splice. Crimp the remaining stripped pink wire into the other end of the butt splice. It will end up looking similar to this:

Note: The picture above is of a different connector, so please disregard the colors.

I used an uninsulated butt splice along with some heat shrink to add a little strength to the connection but if you prefer to use an insulated but splice im sure that will be more than adequate.


Ultimately you will end up with this:


Final step, replace and re tape the plastic wire loom and plug in the connector, you're done! Feel free to turn that temp knob as far to the left as you want without fear of running into that dreaded MAX A/C! But wait, you want A/C now? No problem, its your choice, fire that sucker with a simple button push and feel the cool breeze flowing. The choice is yours now but please use your new found control only for good...

 

great writeup but solder and shrink. don't use crimp connectors on your vehicles

 

Just did this mod - soldered connections. Hardest part is getting the fat fingers to grab those skinny wires! Works great! 13 SR5 DCSB.

 

First new mod on my list as soon as it warms up. Thanks for taking the time to document the process.

 

Thanks for posting this and the very good pictures and drawing. Works like a charm on my '11 4x4 Access Cab. No more "oops, I turned the knob all the way now I need to turn it back a little and then push two other buttons to fix it". Keep it simple, Toyota!

 

Worked great on a 2014 DC. Hardest part was figuring out how to drop the glove box for access! A light application of some Magic Marker 'invisibly' covered up the "Maximum AC" script, too. Thanks!

 

Thanks for the write up. Sub'd!

 

Thanks for the write-up! I've only had my truck about three months now but already figured out what a PITA this was. I'm looking forward to making this mod.

 

Max A/C also automatically enables recirc - does this mod also disable that?

 

Yes. You must push the interior-air recirculating button after the mod.

 

Just did this today. Thanks to the OP for writing this up.

This "feature" has been bugging me since the day I bought the truck. If I want A/C on, I want to turn it on. (And I also almost never use the recirculating function)

 

I'm with you, I HATE that feature as well.

 

The steps for this md are the same for 14's also correct?

 

There are two mods that are very similar. One is Disabling the A/C-Defrost link which is what it sounds like you have done. Fohlkmann did this mod which can be found here:

http://www.tacomaworld.com/forum/2nd...ml#post2395617

The other is the Auto Max A/C Mod which is the post you are on now. They look similar but both have to be done in order to remove the link between the A/C and defrost and disable the MAX A/C "feature".

Hope that helps!

 

I would assume there are very few if any differences in the HVAC system between the '13 and '14 Tacos but it is possible.

One thing you can do is check the air mix damper servo connector for the same colors. Although not definitive, if they are the same you are probably good to go. If you want to go a step further you can grab your trusty multimeter and check a few points on the connector. The pink wire should have 12v to ground with the connector plugged in or unplugged. The brown wire should have voltage on it to ground only when plugged in. The amount of voltage on the brown wire is determined by the position of the temperature knob, 12v when all of the way to the hot side and decreasing in voltage as you turn the knob toward cold.

You can also find a wiring schematic for a '14 Taco and follow it around or compare it with a '13 wiring schematic and look for differences.

 

I did the mod last month and it works perfectly on my 14. I only followed OP original instructions. Did not have to do anything further.

 

It really seems to me like you have done the A/C defrost link mod. The A/C defrost link mod is done to the recirc servo motor connector which is located behind the glove box. The Auto Max A/C Mod is performed on the blend doors servo motor connector located under or below the glove box. You do not have to remove the glove box to do the Auto Max A/C Mod. Also, check the colors on the connector you made the modifications to, the Auto Max A/C Mod uses brown and pink, the A/C defrost link mod uses green and pink. The connectors are even laid out the same so one could easily be mistaken for another, especially in low light such as under the dashboard.

I am currently on a mobile now but I will pull up the wiring schematics and see if I can post some related pictures as soon as I can get on something with a screen larger then 3".

 

Great write up.

 

Great job Dan! I love mods like this! Also, I never saw fohlkmann's mod until you linked the post. It will be nice to have complete control of the A/C and Recirc!

 

Just so I am clear. If I perform the Max AC mod.
1) The temp dial has no impact on the AC
2) If I want AC, I have to press the AC button
3) If I want recirculate, I have to press the recirculate button
4) If I want both AC and recirculate, I press both buttons
5) This has no impact on the AC / recirculate if I select the defrost mode

If I have interpreted the mod correctly, this is great!!!!!!