Auto Temp Control- Blend Door Control - Toyota Nation Forum : Toyota Car and Truck Forums

reidcc · 07-31-2011, 10:00 AM

Howdy Y'all-

I have posted on the Solara forum- but figured I'd get more visibility here. The LCD controlled Auto Temp was available on Gen 4 Camry's as well.

The jist of my problem appears to be lack of granularity on the blend door- meaning no movement or noise from the motor that controls the blend until my LCD says 82 degrees.

I bought 2000 Solara in March of 2010- with ZERO history on it. I'd noticed that as car warmed up my control of heat or mix was lacking. It seemed I had mix for first few minutes, but after 20 minutes into commute- either all cold or all hot. The same thing was noticed last summer and this summer with AC- no mixing at all.

My original thought was sensor- knowing there were two. One was above drivers right knee on lower dash panel- attached to a hose, and the oother is left side of top dash- solar load.

I found an LCD control panel for $30- and swapped with ZERO change. I bought the Thermister Control- the one above driver right knee and also noticed ZERO change.

While under there I played with temp knob and upped one degree at a time. There is a motor control for the Blend Door to the left of radio and heat panels- but behind the console panel. I could see and hear movement of that motor, BUT it only began to move when MY LCD said 82 degrees. It move a little, and then a little more for each degree till 85. When I moved it to HOT- there seemed to be a huge difference in amount of movement(a lot).

I would think there should be mixing beginning around 72 or 73 degrees???Is it possible that motor control is bad? Is it getting a signal from somewhere else besides the front panel?

Any pointers for getting behind console panel?

Does anyone have any idea of what I'm even talking about??

Thanks in advance-
Chris

Woodyg · 07-31-2011, 10:16 AM

Signature Police here...............if you create a detailed signature/profile of your car it encourages people to help you......trust me..I am not like the others

reidcc · 07-31-2011, 01:50 PM

I was able to get to the Blend Door on left side of heater box case. I got 2 of the 3 screws off for the motor, and the blend door operates very smooth by hand- from stop to stop.

It seems as though the motor itself just does not take any input or react to anything until 82 degrees F. the motor itself is a DENSO part # AX063700-7280. A Google search on it brings up only 1 hit...to an Ebay auction.

Do these motors go bad in sucha way mine appears? OR do I still need to do some digging to find where it gets its signal to move from? Unfortunately it does not appear it'll be easy to find another to "try" or shotgun... all Solara's and Camry's that I've seen in boneyards anywhere near here are all manual AC- not ATC.

Thx
Chris

Woodyg · 07-31-2011, 02:17 PM

I doubt it is the motor.I bet it is a semsor and maybe the 82 degrees might be a default setting Did you look on Rockauto to see what sensor or controls might cost.

reidcc · 07-31-2011, 02:52 PM

Woody-

There are 3 sensors for the ATC- one is ambient temp sensor in front of radiator and down low- two is the in car sensor attached to lower valence dash panel(by drivers right knee), - and three is the solar load sensor on top left of dash.

The Ambient temp sensor is reading correct temp- so I know that one's working. The In-car unit was just replaced with a new Toyota part. The third one- I can't seem to get out from top of dash.

One thing I've just noticed(car is sitting in sun right now) is that now I have everything apart, I get no motor movement at all until the LCD say HOT- then it is "stop to stop", which means no blend at all until max reading- then its full hot.

I have moved the car out of sun- and covered the Solar Load sensor with something.

The Solar Load is roughly $40 from the TOY man.

I actually feel better about pulling the console pieces out and other stuff- this thing is getting a good cleaning out!!!

Chris

reidcc · 08-01-2011, 05:29 AM

Update-

I was finally able to pull out the Solar Load sensor yesterday afternoon- I have a lead on another to try out.

However- this morning(out the door at 4:30AM), I just turned ignition on only and fan on low. I cranked the knob for Temp one degree at a time. I heard the motor for the Blend Door kick in at 70. Each degree after I heard the blend door motor move roughly the same amount of time, and once the Temp displayed 84 the motor no longer was heard.

Drove car 10 minutes- and was fully warmed up when I stopped for gas( I was getting heat with display at 75). With engine off- and ignition on, you can hear the blend door motor. However- the trigger threshold had now changed. I heard no motor movement until I got to 75 on LCD display- again- roughly the same amount of movement for each degree, but this time when I went from 85 to HOT- there was a much longer time interval of motor run.

Clearly something else is going on as the car has warmed up to temp. At this point I know its not the Blend Door Motor- as it functions fine when cold. The outside temp sensor is reading correctly, and the in car temp was just changed with new.

I am making a leap here with this next question- but what role might the ECT Switch(under the hood) play in all of this??

This is for a 2000 Solara SLE 1MZ with Auto Temp AC(LCD and buttons).

Thanks-
Chris

dc_98_cam · 08-01-2011, 08:40 AM

... Just looking at the wiring diagram for the 1999 'Auto A/C' ... if that corresponds to what you have.

The Air Mix Control Servo Motor unit has two internal diodes. There is a green wire with a red stripe (G/R) at terminal #2, and a Purple wire (P) at terminal #1.
According to the diagram, if you set the control to full 'warm', positive diode bias is from terminal #1 to terminal #2 ....

If you set the control to full 'cool', the positive diode bias is from terminal #2 to terminal #1.

So, you could remove the motor unit and use the resistance scale of a multimeter to check for internal defects in the diodes. It may be possible to use a diode checker function of the multimeter .... not absolutely sure how that would work out .... it ought to work, though.

One other possibility ... the blue wire on the motor unit leads to the A/C solar sensor, which is some sort of photo-electric element. I think it is located on the top dash ... on the driver side. You could check this component for clean/solid connection, or possibly for photo response of some sort.

Of course, there are the three resistor/sensor elements which you have already mentioned in your posts.

Frequently, you will find that when there is a malfunction, the problem is not necessarily a component failure, but rather the wiring that connects parts together ... sometimes bad wiring insulation, or possibly junction connectors of various types. So, keep an eye out for this problem.
I always spray everything with a plastic-safe electrical contact cleaner ... not the WD-brand though.

***fenixus*** · 08-01-2011, 09:18 AM

sent a PM to OP.

reidcc · 08-01-2011, 10:50 AM

Many Thanks on this!!!

As of this morning- I know the Blend Motor is functioning as I detect movement when fully cold and ignition on. I hear movement for each degree on the LCD. When I checked this morning- I had unplugged the Solar Sensor, and it was completely dark during commute. I wasn't sure what that would have done for me.

Since the Blue wire goes back to Solar Sensor- that must be it... I have not changed it, only unplugged. I may have one this afternoon!!!

I hear what you say on the actual wiring... the solar laod wiring is a real B**** to get at...you can't even get at it without pulling ductwork
Thank You-

Quote:

Originally Posted by dc_98_cam

... Just looking at the wiring diagram for the 1999 'Auto A/C' ... if that corresponds to what you have.

One other possibility ... the blue wire on the motor unit leads to the A/C solar sensor, which is some sort of photo-electric element. I think it is located on the top dash ... on the driver side. You could check this component for clean/solid connection, or possibly for photo response of some sort.

Of course, there are the three resistor/sensor elements which you have already mentioned in your posts.

Frequently, you will find that when there is a malfunction, the problem is not necessarily a component failure, but rather the wiring that connects parts together ... sometimes bad wiring insulation, or possibly junction connectors of various types. So, keep an eye out for this problem.
I always spray everything with a plastic-safe electrical contact cleaner ... not the WD-brand though.

reidcc · 08-04-2011, 05:00 PM

OK- I have changed the LCD Contorl Panel, and the three Temp Control Sensors- the one under ft bumper, the one by drivers right knee, and the one on theft of dash. I even tried the one to right of dash- but thats for lights.

I have no change in function of Blend Door and Motor. I can turn on ignition in AM, and hear the motor opening with each degree change on the temp knob. After one half hour(roughly) something takes over and the motor closes the blend door and blows all cold air until LCD says 85 or HOT.

If I try the same procedure when I am out of work-I will hear and see no motor movement until roughly 81 or 82 or 83 degrees. Keep in mind car has sat all day- so it has nothing to do with Water Temp(was thinking ECT switch)- it MUST be something to do with Ambient Temp... but WHERE and how?

What signal is telling the Blend Motor to close and go cold?

Thx
Chris

dc_98_cam · 08-04-2011, 08:41 PM

The A/C control description implies that the ECT switches ... there are two ....
might be connected to the problem ...
SW #1 has two terminals ...
SW #2 has one terminal ...

The test procedure is described on p. AC-92 and AC-93 of the factory service manual. Remove the ECT switches from the engine, and place in heated water while you measure the temp, and resistance.

I have not found the ECT switches in the A/C wiring diagrams, but the descriptive paragraphs at the end of the section implicate one or the other as a factor .... inputs to the A/C controller ... an output of which is the A/C mix servo-control motor ... which controls the temperature.

The A/C trouble shooting guide also that coolant volume might affect temperature control. Do you have sufficient coolant in the radiator?

reidcc · 08-05-2011, 06:13 AM

Wow-

Thank you dc_98! Someone listed a site you could go to @ Toyota and download sections of the Manual for a daily $10 fee. I should probably check that out.

I just re-read you posting from the 1st- and you mentioned Bias in the terminals at full hot and full cold. The assumption I am making here is that the motor isfunctining fine, and its a SENSE issue.

When sitting overnight- Mix Servo Motor(Blend Door) starts to crank at 69 on the LCD Panel. My commute is roughly an hour- and its dark the entire way. Suddenly at roughly one half hour- the door closes and sends all cold air. The Blend Door motor will no longer respond with ANY movement until LCD says 82 or 83. This happens regardless of whether it is summer or winter.

After work(now)-car has sat for 10 hours in the sun. I'll turn on ignotion and check motor movment- nothing until 82 or 83.

If I remember correctly though- during the Winter it does not do this. I will have "proper" motor movement for the 1st half hour.

At one point I thought I was dealing with something heating up by coolant- and then it appeared it was more of an ambient type of thing.

I had thought of the ECT switch at one point as well- only because I've had a symptom for that. Even on hot days- my 2-3 upshift is delayed for at least the first 3 to 5 minutes. I am not getting any CE lights though.
My Temp guage is always dead center(after intial warm-up).

I had thought my coolant level was fine- I will re-check though.

Thank You
Chris

dc_98_cam · 08-05-2011, 06:23 AM

I think that I get the gist of what you are saying.

The information from the available wiring diagram and service manual is not very detailed regarding the automatic A/C system.

As I have stated previously, there seems to be a link between your problem description and the coolant/ECT switch..... Actually, there are two ECT switches on 1MZ engine.

It may prove to be beneficial to go to the TIS site and download the relevant wiring diagrams and service information available there.
It could be that the TIS manual or available information is different from the older version which is available to me.

... Nothing else to add at this time ... maybe something else will show up later.

monkeycrawl · 08-10-2011, 03:39 PM

Where is the air mix servo located?

reidcc · 08-10-2011, 03:58 PM

I believeit is located on the left side of heater box- which is right behind the console and center stack trim. U can see it above drivers right side, but to get at it the console, lower valence, and other crud has to come out.

Chris