Don't feed the trolls! I think he's just around to be my contrarian. He'd have a lot more fun on facebook.

 

Just becouse you said so?
I can't find as clear heat exchange picture for automotive evaporator, but heat exchanger is heat exchanger.
Here is the best automotive evaporator picture I can find. The coils loops, but the idea of heat exchange is exactly the same as on pictured above kalorifer.
Sorry if you can't understand it.

 

Found another picture that might help you understand

 

What is your problem?

This picture explains exactly the same what I’m saying. One tube zig-zag thru the whole coil. All flow goes thru this same tube with fins attached to it. Every pass is connected to the end of the other so this is what I call series connection instead of parallel tube connection you present.

 

Not to side with anyone here, but I think the point is that the evaporator (fancy for heat exchanger) does not have a uniform temperature throughout; therefore, there is a temperature "stratification/distribution" either side-2-side, bottom-up or in-between (each heat exchanger design has its own pattern) that impacts the flow distribution downstream into a plenum with flaps to control air distribution for the different branches of ducting (top, bottom, left, right combinations). It is up to the flaps to handle the non-uniformity of the air temperature in the plenum downstream.

I have not seen the air ducting for the W212 downstream of the evaporator step, but that is the only place I can see to control anything since the evaporator is a static system: inlet -> outlet

 

Exactly!

 

Glad you change your opinion Arrie.

 

Did not. My exactly is for the air flow handling.

When evaporator is running proper flow it gives pretty much the same temperature on the full surface. What changes temperature is the air flow thru it meaning outgoing gas is slightly warmer than ingoing gas right after evaporation. If you would measure the temperature on a coil without air flowing thru it the result would very much even temperature all over it.

On parallel tube system there is nothing to force the flow thru all of the tubes so you can have some tubes with much less flow that others. Can have tubes even without any flow. Series tubing (only one tube) makes sure the whole area of the evaporator (and condenser) is used.

 

Looks like another case of Alzheimer.
Just in reply #95 you were thinking that regarding temperature whole coil is the same.
In reply #106 you said "exactly" to evaporator not holding uniform temperature.
Now you are saying that you did not change your opinion.
You are giving old people bad wrap.

 

Im done with you. Just another Botus.

 

I'm beginning to think katjek actually does drive a Model T.

 

Now explain, why would you think otherwise?

 

This works! Thank you!

 

Originally Posted by S. Madman
"Please for the love of god, someone sticky my fix. I mentioned this in at least in 3 different threads. Cycle the passenger from coldest to hottest in non stop succession for 6 times. LOW to HI non stop, it will dislodge the flap."
My issue is that the AC works fine and evenly distributes the air conditioning. But, it seems to direct a lot to the dash vents. So I just shut them down by about 3/4's and they work fine. From what I have read, there is probably some type of distribution system failure which may also involve a plastic component running along the top of the firewall. If so, the repair by dealer or indy would cost more than the car is worth.
So, I just enjoy my system of "fixing" it.

 

the aircon flap actuator drivers need a little TLC : lube + solderless pins.


flap actuator opportunities...


solderless pins...


now siliconed up + soldered all right

The hard part is to remove these modules out from under the dash.
The good thing is they are all identical.

The service opportunity is ....
as the electric motor effort increases so does the electric current.
The poor connection become exponentially worse until the AAC Module notices something not right (positioning or temperatures).

 

Thank you, but the above is why it is not going to happen. At least not by me. I also found an online source that referred to some type of long air "conductor"
that is mounted above the firewall that requires removing a lot of stuff just to get to it.
The cost for either would probably exceed the value of the car. So, will continue to use it until AC totally fails and replace the car.

Also, I have noticed occasionally that the AC fails to respond if I lower the temp. setting. In fact, warm air comes out. So, I set it on Max AC and run temp down to as low as it will go for a minute or so. May have to do it twice, but then it starts cooling at the correct temp.

 

Just found this thread. My LAUNCH scanner is also reporting temp sensor n70b1 as a constant -50 C. My AC and heat works fine, it's only that when the outside temp is a bit below the set point (in the fall or spring usually), the ACC will blast out heat even when the cabin gets far too warm. I have to lower the set temp to 61 F, 60, or even LO, at which point cool air returns and remains even as I increase temperature to a normal level (say, 68 F). It's probably still a bit too cold at 68 at this point, but I live with it. If I try to correct by inching the set temp upward, not much happens. And if I go up much past 72 F, it gets far too hot again even if I lower it back to 68. And I have to repeat the whole thing. Pretty annoying. In the summer, it's a non-issue, it immediately decides to blow cold air.

My theory is that the ACC gets confused when the cabin temp sensor by the steering wheel is reporting normal, but the temp sensor overhead is saying it's incredibly cold. (All other temp sensors in the vents, outside, in the evaporator, and the sunlight sensors, report normal values.)

I opened up the OCP and tested the thermistor on the fan, it reports normal values in response to temperature changes consistent with a 10K NTC thermistor. The pins of the fan are making good contact with the socket, I checked with a multimeter. The board looks really good overall, but at this point I'm thinking maybe there are some flaws in a trace or a component that I don't know how to check (or fix), so I ordered a new (used) OCP off eBay so I can try both a different board and fan/thermistor. I also tried setting the n70b1 sensor to "not present" using my bi-directional scanner, I haven't had a chance yet to tell if that's making a difference. (Hoping the ACC will just ignore its reading and go with the one by the steering wheel only.)

All the flap actuators seem to be able to be set to any value without problem. The one fault code that persists is something like "communication failure with overhead control panel," which might be consistent with a bad OCP board. Though all the other functions of the OCP seem to work fine. I believe the fault code given was C-16900, which I can't find any reference to externally.

 

Can you see/hear the OCP fan spinning?

 

I like the way you have this gently figured out so you don't let it bother you the way it's designed to.

What you describe deals with the main BLENDING DOOR.
It sits between the 200F heater core and the 35F AC evaporator - - when it reaches its premature end of life temperatures get wild.

All these A/C actuators are identical... read: well designed system. (you can swap hard working actuators with hardly working ones!)

The AAC controller itself is a solderless gem that handles power - So if it was me I would solder AAC Module before braking my back working under the dashboard on the actuator modules.

 

If the question was about my reply - yes, the OCP fan was spinning.

 

I had a similar problem recently. I pulled codes and there was a problem with the passenger side lower foot well temperature sensor. It turned out to just be unplugged and took 5 minutes to plug it back in.

 

these 120 post long threads are SO much fun when someone replies without any quote context as to what they are referring to...

 

I was, in fact, responding to all 120 posts.