ChromeBenz

My w163 has been working fine till lately, the A/C worked fine this summer, and the heater was fine last winter as well. However, nowadays, no matter how long I leave the car started, the air coming from the heater just isn't warm, even at the max settings. I searched the threads, and ended up changing the cabin filter, but it's still the same. 64K miles, and its not throwing any OBDII codes. Other than stealership, any suggestions, DIY, similar findings, etc?
Thanks in advance

tirkes

Your problem might be with blend door actuator motor. It is located on top of the A/C system (behind the radio) and regulates the temperature of the airflow. You can do a check and/or repair after removing the instrument panel. Good luck!

s4play

hey I have the EXACT same problem and will show this to my buddy - hopefully this works!


thanks
rick

ChromeBenz

tirkes, thanks for the reply, and s4play, keep us posted, i havent had time yet to even attempt anything yet.
Thanks again

s4play

Well, just called my mechanic buddy and the parts will cost about $98.00 and labor they said is 8 hours???? omg....doesn't look that hard, I may attempt to swap it out myself!


rick

ChromeBenz

If you do end up installing yourself, post some pics if possible. Thanks for your help

s4play

I decided to attempt the install myself and have the motor assembly.

Can you guys help me out with finding the EXACT location? It seems I need to remove the radio assembly and temp unit which is easy. But is this "Air Door Actuator / Motor" visible once the radio is removed?

Or is it located more lower behind the glove box?

I'm just trying to figure out if i can tell just by looking at the motor if it's broken since I don't want to replace a part that is not broken!


thanks guys,
rick

btw I just had my crank position sensor replaced and it was faulty EXACTLY like everyone said

Mr Cheeks

The blend air motor is located here

s4play

Mr. Cheeks: Awesome pic - that was VERY helpful! I can't wait to get that section taken out as I already have the glove-box insert removed. Looks like I need to remove the airbag and should be able to gain access


rick

Mr Cheeks

if you go through glove box and airbag route dont forget to disconnect the battery negative you can go through the centre console ie remove the MCS and centre console but access is more restricted

s4play

thanks, I already have the glovebox out and can see that box. The airbag looks like no more than a few bolts to remove....

Will disconnect the battery, thanks for that reminder!

Report back in a few days once I get the part installed.


rick

Mr Cheeks

pics of a broken blend air motor

tirkes

First, it's so easy to remove the radio (MCS). You only need to buy radio removal keys from the dealer for $6 or so. After removing the radio, check the function of the motor. Put your finger on the motor and move the AC dial from hot to cold and vice versa. If it's broken internally, you should be able to feel it. You probably won't have enough space to replace it though. That's why you need to remove the instrument panel as per instructions. Somebody posted this repair by removing the glove box and airbag. Removing the airbag required to break the holding tabs. And these tabs are made to be easily broken at the time of airbag deployment therefore may not be repaired/replaced.

s4play

Update guys: I have my airbag and pretty much the radio assembly all taken out....

I read somewhere on another site you can "Visually" see if the blend air motor is working by looking to see if some level moves???? anyone can shed some light on this?

The blend air motor is held in place by TWO phillips screws. I'm having trouble reaching the one in the front since the dash "bar" is totally in the way!

I removed the 2 smaller m16 screws and those do not need to be taken out.

How the heck did you guys get the front phillips screw pictured below?

here's a pic from another site:

s4play

ok update 2/27/08:

I finished replacing that motor after getting those screws out.......good/bad news!

Good news: When I turn the temp from cold to hot, I can visually see the motor opening and closing that white level so that works just fine.


Bad news: The hot setting is only mild at best and only gets warm when I turn the RECIRC switch ON but that means my windows start to fog up. If I turn on the A/C switch then the air gets cold almost immediately....


My guess is that the car is not getting hot air from the radiator somehow. Or perhaps the temperature sensor is bad since the heat is still not working!

any guesses?

rick

pcy

Just a wild guess...
may be the thermostat is stuck in the "open" position causing the cooant to not get hot enough.

s4play

Great guess but do you know how I can physically check this?

I'm beginning to think I have a bad thermistor that is sensing the wrong temperatures? Since it goes from cold to luke warm but I can clearly see that new motor moving when I turn the temp switch.

How can I check if my heater core is bad or not operating?


thanks
rick

milltek

Well, it would appear that right on schedule our blend air flap motor broke yesterday. Following ideas in this thread and some other I removed the outer section of the dash top and then the air bag and finally, the broken motor. Now my question is how to re-attah the outer section of the dash that covers the air bag? When removing it I broke two cream colored pieces of plastic that keep the front edge down tight? Are these sold by the dealership???
Or is there an alternative way of re-attaching it?
Thanks

Jim

ChromeBenz

I believe those tabs are supposed to break in the event of an accident to allow airbag release. You can't replace them, I think local stealership may have to intervene, though since you've done most of the work, it probably can't cost too much to put the cover back on, but you definitely shouldn't try any other way to place it back on yourself, since it can prevent airbag from deploying in the event of an accident. Check with your local shop.

puhuta

Remembering the first time I took apart a dashboard only to have it never fit right again, does anyone have any steps for removing the necessary parts of the dash in order to get at the blend air motor without going through the air bag cover? Thank you.

Slugward

See the grille/vent in this picture below the Low Range Switch??

Well, there a NTC resistor (sensor) behind this grille below the low range switch senses the in-cabin temperature. A white hose (about 5/8" diameter) connects it to the main climate box thus drawing air across the sensor. This sensor is directly behind this grille (if you look carefully thru the grille in this picture, you can sor-of make it out) Anyway, the air temperature is controlled by a variable resistor rotary control. Signals from the resistor to the amplifier determine the desired interior temperature output of the system. A switch at detent position at the full counter clockwise (maximum cooling) position overrides the air recirculation switch to close the fresh air door for maximum interior cooling (with A/C on). I'm not kidding, by dumb luck, all I did was to push the hose back on and my Blend Air started working as advertised!!

To access this hose, follow the instructions for pulling the radio in this thread. Once the radio is out, it is easy to push the hose back in place behind the sensor.

BTW, hats off to all posters on this site...you guys/gals have saved me a butt-ton of $$$!

kazphil

Just fixed our acutator motor and took approximately 10 mins. We had problem with a/c not being cold but all working ok and it seemed like the heater was stuck on.
Fixed by removing radio surround cluster as mentioned in an earlier thread. Took out heater control cluster then removed pocket under radio and then removed the radio and remove outlining trim around radio etc.
Located actuator motor, started car and turned the temperature control switch, then gave it a slight push and it started to work properly.
Appears it may have just been jammed due to the fact that we live on the Gold Coast in Australia and the heater is rarely used, when it was turned on it obviously stuck, then A/C would not work.
Thanks to all hints on this site - which have worked for us. Good luck to anyone else who has this problem.

CE_BRENT

Had the same problem, a '99 ML with the heat stuck on in the middle of an L.A. summer. However by just removing the glove box, I was able to reach the gear mechanism, and free it up. I added a little white grease for good measure and we'll avoid full heat for a while.

We'll see how it works out..

shadetree mecha

My A/C not working. For a while it was intermittent. I would turn switch on and off. Seems if I left it in one position, cold, it would stay cold. But put heat on last winter and now full on heat and never any cold. Not a mechanic. Just trying to figure out if it's worth fixing a 120k truck. How much to fix? Estimate?

soflofly

My Climate control is stuck on Hot. We just went through 10 days of record freezing wheather here in South Florida. I could hear the motor clicking as in "getting stuck". Finally its done for and stuck on hot.
All the posts have all been very helpful. I decided not to mess with the dash board for now. I needed a quick solution and since we really do not use heat very often; I Opted for a "by pass" solution. Removed coolant tank. Removed the two hoses on the fire wall behind the radiator coolant tank. Manufactured a "U" Pass through from scrap 1/2" copper tubing. Attached the two hoses together and sealed the stubs for the heater coil. (keep dust out) Put every thing back together, added coolant and prayed. Seems to work just fine. One bad thing; I need to figure out how to insulate that copper tube, Worried it might get hot and it can only rest on two things. The cold a/c line or a wire harness both on the fire wall.

I ain't MB quality work, but it sure is a quick fix just for now! South Florida is hot, especially if you have a tie on!