Mazda3Club.com : The Original Mazda3 Forum - 3G Protege: HVAC - Disabling A/C In Floor, Floor / Defrost, and Defrost Modes

Begin by removing the glovebox. It helps to sit in the passenger seat. Squeeze the sides together near the top, and it will fall down more. Pull on the left side, and then once it unclips, remove it and set it aside.

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Next, locate the cable for the temperature selector. It's a metal cable attached to a white plastic mess. If you need help finding it, move the temp selector and see which one moves. Disconnect the cable from the white thing as well as the holder that can be seen about 3 inches away.

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Now, move to the driver's side footwell and locate the mode selector cable. (Follow same procedure as above for removal.)

Now that bothe calbes are free, remove the center trim panel. With the vents all the way down, just reach in and pull. It will take some force, but don't worry. It won't break.

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Disconnect the hazard lights, as well as the HVAC controls. Be sure to note routing of the two cables you removed earlier. (Found this out the hard way!)

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Now that the unit is free, remove the HVAC unit from the trim piece using the 4 screws. (Now is a good time to paint the trim piece should you choose to do so.) Set aside trim piece.

Now that the unit is out, pull off the knobs and remove the black faceplate.

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Unscrew orange plastic card. This is what gives the HVAC its red color. Should you wish to change it, make a template from a spotlight gel.

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With that removed, you will see a circuitboard. DO NOT PULL ON IT!!! Remove the mode selector cable from it's holder atop the unit. Remove the black plastic cover on top of the unit and set aside. This is a time-consuming step, but just take your time and be careful.

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Once the plastic cover is removed, you will see a circuitboard. Remove it VERY CAREFULLY. (It is attached to the first circuitboard.)

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Locate the two microswitches. De-solder, use a dremel, silicone, tape, gum whatever you shoose to break the connections on the switches. De-soldering is the cleanest way, but takes a long time. I just cut the switches off with a dremel and made sure the 4 "terminals" on each switch weren't touching using a soldering iron on the reverse side, leaving 4 holes in the board for each switch once the solder was all removed.

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Now, replace the circuitboard and plastic cover. Re-install cable into it's clip atop the unit, and install orange (or another color if you choose) plastic. Re-install faceplate, and knobs. Verify correct alignment and operation of mode and temp selectors. make sure all buttons and knobs move freely.

Re-attach HVAC unit to trim piece using the 4 screws, and re-install into car, keeping in mind routing of the two cables. Re-attach hazard light switch, and HVAC cables. Verify hazard light operation. Re-install entire unit into dash. (Just snaps straight in.)

Now, re-attach the cables, re-install the glovebox and start the car. Crank the fan to speed 4, and verify temperature and mode selectors function properly. In ANY mode (Panel, Floor, Defrost, etc) the A/C SHOULD NOT come on without the button being pressed. If the A/C is on without the button being pressed, you didn't break the connection when you de-soldered. (Both engine fans run when the A/C is on.)

If the A/C works only when the button is pressed, good work!

Please note, the windows may fog up even if full heat is selected in defrost mode. SImply engage A/C to de-humidify air. In most cases however, the heat will warm the windshield enough to prevent condensation.