Brad Clayton Posted September 7, 2014 Share Posted September 7, 2014 Ever wonder what goes on inside of one of these dual climate control setups? Here is an inside look. This is the bottom half of the case torn down to the bare nuts. 1 is the driver's floor door, 2 is the passenger floor door, 3 is the optional aux heater slot, 4 is the heater core slot, 5 is where the mode door resides. This tray separates the case into two halves. Both the mode door and the temp doors must be split to fit between the separator for the dual climate control so it will function as if it were a single plenum chamber. Here you can see the mode door is keyed and both doors will move together. The mode door is operated by a cable and is located on the very bottom of the case. These are the temp blend doors and as seen here they are keyed because this is a single climate controlled unit, if the dual option were on this rig then these doors would not be keyed together so they could operate independently. Air diffusers. 1 is the evap core slot, 2 is the heater core slot, 3 is the aux heater slot, and 4 is where the blend door resides. Dual climate control will allow the blend doors to pivot independently of each other here. The driver's blend door will attach at the bottom of the case and the passenger's blend door will attach at the top of the case. If the option is not available then there will be just one blend door motor on the top. The mode doors cannot be operated separate from each other. Lower (driver's) air diffuser in place. Case being assembled up to the point minus the upper (passenger) air diffuser. This is a good shot showing why a case without the aux. heater can't be upfitted. With the separator tray in place you can see there is only a provision for the heater core to fit in. Here is the blower motor resistor. I hope these things never fail. I am not sure how you would get this out without removing the case or at least unbolting it from the firewall and doing some barbaric prying. The unit locks in with a tab and slides in the case towards the blower motor to lock in secure. To remove, simply push down on the tab and slide towards the driver's side of the vehicle and remove. Case assembled and waiting for the defroster panel door. The left side bottom (with foam surround) feeds the driver's panel vents, top left feeds the driver's defrost and floor vents. The passenger's mode door can be seen and the driver's is hidden below it. Defrost door in place. The main control of the whole assembly, the blend door actuator and mechanisms. Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted September 7, 2014 Author Share Posted September 7, 2014 The mode door mechanism must be completely disassembled to replace the motor. As the motor bolts from the inside of the frame. Mode door lever goes on top of the motor. Worm channel assy goes on next and the bottom channel will control the mode door. And lastly, this mechanism rides in the upper worm channel and controls the floor door and the defrost door. All in all, I have to say this is a well thought out and nice little unit to work with. The wiring harness is routed very securely to all the motors and is easily checked by accessing the 2 connectors behind the glove box. The mode door apparatus is an engineering marvel and quite the concert to watch in motion. The only two issues I see, are the blower motor resistor and it's difficult access (however it is heavily heat sinked and may never fail), and the fact that loose items can easily find there way from the package tray on the top of the dash to the bottom of the HVAC case via the defroster vents. When this happens the mode door ceases to function correctly. Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted September 7, 2014 Author Share Posted September 7, 2014 A quick vid of me doing a stumbling narrative of the mode door. http://youtu.be/vehphhfDgIw Quote Link to comment Share on other sites More sharing options...
forddieseldoctor Posted September 8, 2014 Share Posted September 8, 2014 Pure curiosity... What was the reason for having this unit out? Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted September 8, 2014 Author Share Posted September 8, 2014 The customer couldn't change air flow direction, it was stuck on vent all the time. I had to tear it out and apart to retrieve all sorts of bits that fell down the defrost registers and jammed into the mode door. Quote Link to comment Share on other sites More sharing options...
tonybullitt Posted September 8, 2014 Share Posted September 8, 2014 Nice job on the write up and pictures. My coworker had to replace a mode door motor recently and we were looking at it thinking that resistor is a joke mounted in like that. 1 Quote Link to comment Share on other sites More sharing options...
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