Is there a simple way to make my ACC always blow hot?

[1980sdga]

If you want to retain the blower speeds and the bi-level, etc. functions without the automatic water valve you could try this:



My water valve was jamming the system so I removed the valve 

With this and a manual proportional valve control you'd have Semi-Automatic Climate Control!

[1980sdga]

An update on the Astro van valve:




I took the vacuum part of the valve apart (it snaps together) removed the vacuum diaphragm, flipped the spring parts around and made it a mechanical normally closed valve    The rod goes all the way through the pod now and the pod just houses the spring mechanism and acts as a guide for the actuating rod.

I'm thinking about an electric solenoid to control it but it would be nice to have 3 positions. "closed" "half-open" and "open"

Open/closed won't be much trouble but I'm stumbling on a part open solution...

The soup kitchen is open 

[Casey]

FYI, a possible solution:  http://mercedessource.com/node/606

[1980sdga]

FYI, a possible solution:  http://mercedessource.com/node/606

That's an OK solution but I don't know if I'd want to live with a push-pull cable. I'll bet routing it would be a PITA.

Astro valve in place:



This valve is also a return valve which allows coolant to bypass the heater core when the valve is closed. It may be to keep the aux. pump from "deadheading"  and preventing air pockets.

The astro valve seems like a flimsy thing...

[Papalangi]

My plan, which may never actually come to fruition, is to use a similar valve but mechanically operated instead of vacuum operated.  I have the heater valve from a mid 00's Ford Ranger and plan to mount an RC servo to it.  I'll use a 555 or 5556 based servo tester circuit to drive it and use the temp wheel in the console to control it's position.  Low end of the range will close the valve and high end will open it.  My fan works in all speeds so that's really all I need.  The AC has a rather large leak at the compressor and I'm too lazy to fix it so I don't have to worry about that part.

My servo is stuck such that I get air from the defrost and vents at the ends of the dash but nowhere else.  That works for me since if it's cold enough to need heat, the windows are fogged due to the many water leaks.

Michael

[1980sdga]

Maybe something like this:



I have zero experience with this type of stuff but it looks like it would be fun to fool with. I was thinking about using the "semiservo" to drive the pot that controls the servo that controls the water valve 

I've been running with the valve either fully open or closed manually and it's not a good solution. When it's only 50 F you need a little heat not the furnace roaring...

[scraf]

EDIE: Just read the admins thread about staying on topic, so will start new thread.


.... since you're all gathered here.

The heater/fan on my W116 is giving out warm air for about 45 seconds, then turns lukewarm/coldish.

Anyone pointers ?

After an afternoon of messing around with it and other things, I'm hoping it is something that can be fixed with a hammer.

( the air co has been removed, or whatever parts of it got in the way of the last engine replacement )

[Papalangi]

Maybe something like this:

<snipped to reduce size of response>

I have zero experience with this type of stuff but it looks like it would be fun to fool with. I was thinking about using the "semiservo" to drive the pot that controls the servo that controls the water valve 

I've been running with the valve either fully open or closed manually and it's not a good solution. When it's only 50 F you need a little heat not the furnace roaring...

Yup, that's pretty much what I'm thinking of.

You can buy one as a kit for $15US,
http://www.gadgetgangster.com/find-a-project/56?projectnum=206

Or poke around here for ideas and info,
http://www.horrorseek.com/home/halloween/wolfstone/Motors/svoint_RCServos.html

This is what I was planning on using but I don't think I need the accuracy that this circuit has, I just want hot, warm or cold,
http://www.seattlerobotics.org/encoder/200210/servoex/ServoExcerciser.htm

I don't remember what value the temp dial pot is but it's probably not what is used in these circuits.  It would either need to be replaced or changes made to the resistors to get full travel out of the servo. 

Michael

[1980sdga]

My test procedures say to adjust the thumbwheel until the pot reads 900 ohms with the control centered at 75.  It doesn't say what the high and low values should be...

My astro van switch isn't working correctly or I have it in wrong or something...  I thought the bypass function would be close to original but it seems to always be moving water through the core. Even in what should be closed position the brass tubing in the cabin is still pretty hot so it must not be blocking flow.

[Papalangi]

Unwired tools sells a replacement pot.  It says it should read 1500 ohms at 85 and 300 at 65, so I'm guessing that it's a 1500 ohm pot.  It could be more and 85 degrees could be a hard stop before full travel of the pot but I don't think so.  It shouldn't be too hard to tweak the resistor value to get the range we'd need out of the servo.  Even if I can't figure it out, it can be replaced easily by grinding flats on a standard value pot.

The Ford valve looks like it was made for a servo,


I'm not sure how the Astro valve works but it might be directional, meaning that if it's backwards, it can't fully close.  Kind of like a check valve.

Michael

[Ilike300sd]

here are some more valves fyi 

http://www.nostalgicairparts.com/ac/heater-valves-and-cables-95.php