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I would if I was you. You may be surprised how often that stuff happens, but when I took apart the old one I found the electric motor worked and the part it moved did not seem to be stuck. Not exactly sure how it failed.
The car I was working on would start to blow hot in the back after 20 minutes. I took out the command and all of that stuff for nothing, but I did learn where the blend door motors are. I would definitely try a new OEM part, and then go from there. Let me know if there is anything else I maybe able to help with.
Where are the blend motors?
I did change the change over valve same diff. One side hot the other cool. Also yesterday hot both sides, got in and out during the day and then one side was cool again. Very weird, thinking its blend doors or evap sensors as greasemonkey suggested to me, will have to see what star says.
The valve for the rear is in the front passenger wheel well by the front passenger door.
The valve under the front cowl is for the front climate control
So, my alternator just died (I believe, possibly the voltage regulator, but there's a strong electrical burning smell). I kept having intermittent electrical issues (moon roof keeps needing to be re-set for instance)... I wonder if I was having intermittent voltage issues that was throwing the AC off.
While the issue seems to be happening less, here's where I'm at:
1). It occurs when the engine is hot. On mild days it rarely occurs. It needs to be a hot day and a hot engine.
2). There's no specific temperature setting, or change in setting that triggers it.
3). It corrects itself if I set both rear temps to "HI" and back down to any normal temp. It goes hot again after 15-20 minutes.
4). I replaced the heater control valve again (twice now) and it didn't change anything. So I'm confident that's not it.
5). I've addressed every electrical gremlin that I've had. There are zero other issues with the car electrically.
So, I'm down to two things... The blend flap motors, or the SAM. I think it's the SAM, since on a 90 deg day, I don't see why the heater core should receive any hot coolant at all. My theory now is - when the car gets hot, a chip in the SAM gets screwy and tells the heater control valve to open. Does this make sense, has anybody experienced this?
Since I don't have STAR, I'm going to try and replace the heater control valve chip... It seems like a stretch, but at this point I feel out of options.
I'm not 100% sure yet, but I may have finally tackled this. Just took her for a 45 minute drive with no issues. I cycled through all different temp settings. I'll have to wait for a few 90 deg days to be 100% sure. I'll post an update after a few drives to verify.
I ended up replacing the control valve chip in the front SAM following this YouTube vid:
I'm not 100% sure yet, but I may have finally tackled this. Just took her for a 45 minute drive with no issues. I cycled through all different temp settings. I'll have to wait for a few 90 deg days to be 100% sure. I'll post an update after a few drives to verify.
I ended up replacing the control valve chip in the front SAM following this YouTube vid:
Below are some pics of the SAM, how to remove it, and how replace the chip...
To remove the SAM, disconnect the negative battery cable, then remove the blue circled items (connectors, bolts, and power cable nut). Pull the unit out slowly.
Remove the connectors slowly and take pics for reassembly...
Remove the connectors slowly and take pics for reassembly...
SAM connectors....
SAM Removed
SAM Removed
Remove the 5 T10 bolts and backing plate to expose the circuit board.
Remove the top board of the SAM by CAREFULLY prying the plastic clips with a small screwdriver.
Top circuit board removed
Carefully pull out the circuit board
Heater valve control chip with new chip sitting next to it
Who had the hook-up on the chip and about how much was it?
I am having a problem with my climate system, but it is a different problem. My "mode" selector does not work and it was stuck blowing out of the vents by the feet. Very weak airflow in the upper vents. I could not close the flap in the lower vents manually, but cramming a rag in there helped force a little more air through the upper vents.
Last year I replaced the heater control valve under the windshield wipers. Last week, I had the hose in the low pressure system replaced (There's a TSB on it as the inside of the hose is prone to collapse) and I put in a new desiccant canister. System was refilled. I have a laser thermometer and I took some measurements before and after.
Driving to the shop, outside temp was 91 degrizzles. With the ac temp set to LO, the lowest temperature I could find was 48 degrees. After the repair, outside temperature was 100 degrees. The lowest temperature I saw was 34 degrees. That was with aiming that laser down inside the vent.
Now if I can just fix the airflow issue, I'll be good to go.
^ As far as the chip, a member posted that he had an extra one. I believe if you search for the chip based on what its called in YouTube vid or based on the letters that are on the one in the above pic, you can find it.
As for a status - I'm happy to say that this has completely fixed the issue. Two days of muggy hot weather and lot's of driving, and the AC has been solid as a rock!
2003 W211 Avantgarde (Sport), 2007 E550 Sport package
There is no programming for the IC, it is a simple "driver IC" meaning its a IC that takes control voltages/signals from the SAM and outputs the correct voltage/polarity to drive the small DC motor in the changeover valve. The IC costs about $3.00 or less. When your changeover valve leaks and destroys the DC motor in the valve the SAM will still try to switch the changeover valve but cant because the DC motor is seized or has a short in it which can destroy the L9997ND driver IC that is directly connected to the changeover valve.
Ok thanks for reply. I left the board by a tv repair man and saw him start cutting before I left his shop. Had no choice left as no electronicservice shop accepted the job. Now I have a kind of 50/50 feeling while waiting for his call.
If anything has gone wrong during disassemble/soldering process, is it only the function of the climatecontrol I will lose?
Has your problem ended after this op.?
Ok thanks for reply. I left the board by a tv repair man and saw him start cutting before I left his shop. Had no choice left as no electronicservice shop accepted the job. Now I have a kind of 50/50 feeling while waiting for his call.
If anything has gone wrong during disassemble/soldering process, is it only the function of the climatecontrol I will lose?
Has your problem ended after this op.?
The guy who soldered it for me had it done in 5 mins, no cutting... It has worked perfectly since.
I'm not sure what else will go wrong if he does it wrong.
I will. I think I will get it back tomorrow. On Sunday I will put it all back in the car and see what happens. I wish everybody a nice weekend and whoever read this,please hold your thumbs.
05-20-2015, 10:23 PM
