Has anyone ever changed out the manual heater control (SR5)in the dash to the auto style(Limited)??..I just got an auto digital readout temp heater a/c control and I'm swaping out the manual rotary knob control that came stock in the truck but the new auto control does not seem to function correctly..This unit I have came out of a wreck (front end damage) from a salvage yard. The plug on the rear is identical on both the auto and manual...
I have been wondering about this myself. A while back someone posted the same thing saying it did not appear to work right. We really need a schematic to figure out if it works or not. I remember seeing something about a thermistor and that may be needed for the auto part to work correctly. I am just throwing something out there from looking at the parts diagrams online. If we can get to see a schematic, I think that will tell us. I see no reason why it should not work, especially if it has the same connectors. Let see if we can keep this going and get it working for you as this is a mod I would love to do and I am sure there are many more that would.
I looked inside both controls and there is what looks to be a thermistor or a similar looking device inside the auto control so possibly it is built in and senses the heat -a/c right near the unit although that would probably not be very accurate but I wonder where else in the truck the sensors would be placed and there would possibly need to be two sensors one for the driver and passenger..I'm gonna look into this I really would love to have the auto controls..both units look pretty much identical inside..Now I have to search out a wiring diagram or get a hold of the pin-outs of the plugs on an SR5 vs a Limited and see if the pins are the same..
If you get a schematic or pinout, post it and we can try to figure it out. I've never used the Toyota tech site, but I believe you can subscribe by the day and download tech info. It might be in there.
I used the tech site before but that was before I had this swap in mind so I do not have that particular wiring diagram ..I am into electronics so I'm fairly confident once I get a hold of the pin outs I can get it to function unless of course this auto control I have is junk to begin with..
Me too, I am an RF Design manager, so I am big into electronics too. If I can be of any help let me know and hopefully we can get it working for you. How much did you have to pay the scrap yard for that piece?
See if this helps you guys. I know nothing about AC or Auto electronics. It does appear that if you want the separate driver and passenger controls, there needs to be something that controls the air dampers separately, plus a few other things such as separate driver and passenger temp control and digital read outs etc.
From looking at the diagram above there are 2 things on page 431 that say are specific to the Auto Climate control, a solar sensor and room temp sensor. Not sure if these are plugged into the unit or not or where they would be. Is the Climate module called an A/C amplifier? Also on pages 433 and 434, there is something different about the blower assembly. It says auto climate. I wonder if the blower assembly needs to be swapped as well?
I'd pay $150 for the module. That seems pretty reasonable.
From looking at the diagram above there are 2 things on page 431 that say are specific to the Auto Climate control, a solar sensor and room temp sensor. Not sure if these are plugged into the unit or not or where they would be. Is the Climate module called an A/C amplifier? Also on pages 433 and 434, there is something different about the blower assembly. It says auto climate. I wonder if the blower assembly needs to be swapped as well?
I'd pay $150 for the module. That seems pretty reasonable.
Steve
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Just a guess on the blower motor; most manual systems have 4-5 speeds via a register or electronic controller, and most auto systems have either infinite speed control, or a few more speeds to make the variations in fan speed less noticeable. Have never looked at Tundra schematics, but the new Sequoia which has auto temp control has 9 speeds for the front HVAC cabin fan according to the info posted in the now current post discussing the aux condenser fan.
Thanks for posting that good stuff. The one main thing that is different on the connectors is the driver and passenger solar sensor and the room temp sensor for the auto control. The controls for the blower seem to be the same. Interesting, now we are getting somewhere... It looks like the Room temp sensor is behind the dash and the solar sensor is up on the dash near the defrost vent. I have a feeling with those extra inputs this might work, but we would need to add those in as they are not there.
I did some research on auto a/c conversion and I'd like to share my findings and correct some misconceptions:
1. the one part that you will definitely need is "room temp sensor" (aka thermistor, costs $25 at the dealer). there is only ONE such thermistor for the truck, located behind the driver side "knee" panel. the 2pin harness is right there, I checked on my sr5 Tundra. do not confuse it with a different type of thermistor that's for the evaporator. the later one is on all models.
if you try to hook auto climate controls into sr5 tundra w/o extra parts (room temp sensor) the a/c will keep showing LO temp setting and max blower. you won't be able to operate it.
2. the temp control is ALREADY separated even on SR5 model. there is no separate blower or damper for driver or pasenger side that is not on sr5.
it's is true that Ltd Tundra has one more damper built into the case. that damper is called "cool air bypass damper". that single damper is common for both driver and passenger side, and it's sole purpose is to direct somewhat colder air to upper vents during hot days. that happens ONLY in Auto mode. if you manualy set the blower speed and direction of air flow, that damper remains in a closed position. in auto mode however, you set the desired temp and that's what blowing from the lower registers, but on hot days the "bypass" damper opens up so the air blowing from the top registers will be a bit colder than whatever temp you set.
Thanks for posting that good stuff. The one main thing that is different on the connectors is the driver and passenger solar sensor and the room temp sensor for the auto control. Steve
there is only ONE solar sensor in the ltd Tundra, located on the driver's side, at the windshield. there is no solar sensor (aka light sensor) on the pass side. perhabs there may be one in the sequoia. the toyota documents are common for both models in that regard.
the sole function of the solar sensor is to info the climate control that there is a sunny day ---> that means that the solar rays warm up the skin and the uper body will feel somewhat hotter that the rest of the body ---> therefore the [earlier mentioned] "air bypass damper" will open up and the air blowing from the upper vents will be a little bit colder than the set temp. all of that happens only in auto function mode! if you manualy set the temp and blower, the solar sensor feedback is DISREGARDED.
the solar sensor provides the a/c amp module with the output voltage of 0.8 to 4.8 Volts depending on how sunny it is. anything below 0.8 volt is considered by a/c amp module as dark/no sun condition.
BTW I have two mint condition auto climate controls from ltd 07-08 tundra that I just got recently (had to buy both at the sme time) and I'm looking to sell one. pm me if you're interested
Change Manual a/c heater to Auto digital
Re: Change Manual a/c heater to Auto digital
Linear Mode
