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A/C will not shut off, drains battery

3K views 41 replies 6 participants last post by  mrboca 
#1 ·
A/C motor in my 1999 E320 keeps running after I turn of the ignition. I tried to figure out which fuse controlled it but could not. I had to disconnect the battery so it would not die. Any suggestions as to how this happens and how to fix it would be appreciated!
 
#5 ·
@;

If you are talking about the blower motor inside the cabin, then you need a new regulator. Remove the old regulator connection in the meantime from the blower motor. The regulator supplies a pulsed 12V to the blower motor to control the speed based on input from your climate control unit.

Maybe a reset of your climate control unit may help.. Can you control the blower speed from the climate control buttons ?

Or are you talking about the fans in front of the radiator ?
 
#6 ·
Yes, inside the cabin. I replaced the regulator 7 months ago. Will disconnect. If it stops then will get a new one. Not sure how to control the blower speed from the climate control buttons but I can run the diagnostic codes to see if one comes up. Will update forum soon. Thanks to you and Hamada :O)
 
#9 ·
Yes I know about those buttons, thought you meant something else. I can use the console to run the diagnostic codes too. Replaced the blower and resistor (and evap temp sensor) myself before. Resistor is porcupine kind. Will update after I fiddle with regulator. Thanks!
 
#10 ·
Unplugged power wire to blower motor so it's not using the battery when the ignition is off.

The temperatures follow the climate control up and down buttons.

Fault codes are eb234 (sun sensor) and eb422 (K1 series interface connection to instrument cluster). I doubt a faulty sun sensor would cause the blower to keep running. Not sure if that means the resistor is bad (?) I replaced it 7 months ago.

I found this post on this site from nidgster in 2010:
K1 and 2 are the twisted pair of wires that are used to send and receive data to and from the AAC and IC. They are not actuators, sensors or control units, just a two way communication path, however like you read in WIS they are not redundant, therefore if K1 goes out the data is not shifted to K2 like a CAN bus.

The AAC unit has default values stored to act on when the K1 and K2 are not communicating. The bad news is that the system will not function as designed----you will notice little things such as read out in C rather than being converted to F; fan speeds etc.

To cure the issue you have to look at the connections at the AAC and IC or when you took out either unit one broke or one became disconnected.
 
#12 ·
""The temperatures follow the climate control up and down buttons.""

the buttons we had referred to was for the blower fan speed, not the temperature selection.

The question was, when the blower motor runs when you press the buttons at the bottom row in the middle (- and +) , does the blower output go up and down ? when you keep pressing the less air the climate control systems turns "OFF".

I do not think K1 and K2 lines with the display panel have anything to do with the fan speed control. You need to go to the diagnostic menu and look at item 10 (fan control voltage) as you press the + button you will see the voltage will increase. This voltage controls the porcupine regulator. If it goes up and down with + and - button pressings, your regulator is the one that has problems.

 
#19 ·
If your fan speed is set to minimum, yes.. If you press the + several times to increase the fan speed and then , then go into diagnostic mode to look at 10 I think it would be higher.. I just wondered if you were able to keep pressing the - button when the regulator was connected to the blower, and turn the blower OFF that way ?

Please post all the diagnostic values (1 to 40+) per the youtube
 
#20 ·
Fan spins high regardless of the setting of (+ and -) buttons .
DTC #10 readings increase/decrease with the 7 settings of the (+ and -) buttons

DTC - Cold Engine:
1 69
2 60
3 73
4 73
5 71
6 105
7 06
8 73
9 27
10 (7 button settings: 0.8, 0,8, 1.3, 2.0, 2.7, 3,5, 6.0 (fan runs high when unit is set to off and stays high at all settings)
11 2.0
12 4.2
20 3.2
21 32
22 00
23 32
24 11.4
40 164
41 85
42 104
43 136

Thanks
 
#21 ·
Well, thanks for the readings.. It appears your climate control gives out the right voltage levels in steps as you press + button. While there is a small possibility that the climate control output voltage to the regulator is not following what is displayed (permanent 6 volt), the most likely cause is the defective regulator. The output transistor(s) that drives 12V pulses in the regulator is probably shorted. You could just unplug the climate control connector to the regulator to confirm.

You indicated you changed the regulator 7 months ago already. I am not sure which one you got but there are many low quality and cheap regulators out there that are destroyed due to overheating.

Make sure you change your cabin filters too if you have not done so recently. Severe airflow restrictions can cause overheating.

I assume you took the readings when the engine is not running. Your battery voltage level at 11.4 is low. Make sure you re-read it (item 24) after you run the engine. It should read about 13.2 to 13.5 volts.
 
#22 ·
Well... let's try to get onto a solution track... you had posted "Resistor is porcupine kind. Will update after I fiddle with regulator. Thanks!"

From the description and thread - your blower continues working after ignition is switched off - am I reading this correctly ?

You have listed a 1999 E320 - the original blower that came with your 1999 E320 was the "W140 type" resistor/regulator - and later Mercedes "updated" that part to "porcupine type" and "porcupine type" updated regulator also requires updated blower motor as well.

If you have original 1999 blower motor - unless the blower motor was later replaced with "updated type" original blower the correct replacement is "W140 type" splice in resistor available from eBay/aftermarket - and properly mounted with "thermal paste".
 
#23 ·
Well....

Well... let's try to get onto a solution track... you had posted "Resistor is porcupine kind. Will update after I fiddle with regulator. Thanks!"

From the description and thread - your blower continues working after ignition is switched off - am I reading this correctly ?

You have listed a 1999 E320 - the original blower that came with your 1999 E320 was the "W140 type" resistor/regulator - and later Mercedes "updated" that part to "porcupine type" and "porcupine type" updated regulator also requires updated blower motor as well.

If you have original 1999 blower motor - unless the blower motor was later replaced with "updated type" original blower the correct replacement is "W140 type" splice in resistor available from eBay/aftermarket - and properly mounted with "thermal paste".
 
#24 ·
#24 with ignition on = 13.3. It's the original blower motor. The porcu resistor that I installed 7 months ago cost about $75. I changed the cabin filters then. (yes the blower motor keeps running when ignition is off)

When I purchased the replacement resistor I also purchased a blower motor (both from a discount online the dealer told me I needed both. Dealer was going to charge me more than $900 to fix everything so I said I will try to do this myself.) Their connectors did not match so I tried connecting the new resistor to the old blower motor and they matched. That is why I kept the original blower motor.

I suspect that either the new resistor and the old blower motor don't match up in current/voltage correctly or I bought a crappy resistor.

I'm unclear about the suggestion to buy W140 parts. My car is W210. And am I going to need to splice the wires? Or can I buy parts that fit and work without having to splice wires? The problem with buying parts online is when you indicate the parameters for your car there are 10 choices of resistors and motors and the prices can vary by hundreds of dollars.

Thanks a lot guys
 
#25 ·
Was your original regulator like the one below ?


New AC Blower Heater Fan Resistor Regulator for Mercedes Benz S500 320 420 300 | eBay

If so, then you could have ordered and aftermarket unit like this with no wiring splicing. I do not see how you actually "matched the porcupine regulator to the old blower.

The part of the old blower at the bottom where the regulator is bolted on is made of hefty metal and acts like a heat-sink. Thus, when you install the old regulator to the old blower, you need to be absolutely sure you use thermal paste on the bottom of the regulator to improve heat transfer.

I have 1998 e320 and mine (original) failed about 3 years ago, and I bought one of these aftermarket ones. No problems at all. As I said, the crucial part is the correct installation with thermal paste, not too much not too little, just to fill up the surface imperfections.

The porcupine has its own heat-sink so the new blower does not have the heat-sink metal framing. It is possible that old blower may require more power to run than the new one.
 
#26 ·
"Was your original regulator like the one below ?"
No, it was porcupine. I ordered:

BLOWER MOTOR
PART#: REPM192013
MFR#: REPM192013
Replaces OE Number: 2108205242
MODEL TIY-40309
http://www.partstrain.com/store/det...otor/1999/Base/6_Cyl_3-dot-2L/REPM192013.html

My order was for the blower motor and resistor together, see the 3rd one down at
http://www.partstrain.com/store/??N...6238+4294967029+4294966778&Nr=AND(universal:0)

Later this is what I emailed them about the incorrect fit when I returned their blower:

The plugs on the blower motor electric wires that you sent do not match the receiving plug on the car's wire. The wire of the original part (i.e the blower motor that was already in the car) has two cylinder-shaped male ends inside a plug that fit into two female tubes inside the plug to the car. The wires attached to your replacement motor are separate and have different plugs that do not fit into the car's (female tubes) plug.

So I want to make sure I order part(s) that match in power and connection/fit. Thanks.
 
#28 ·
Krikey - not sure why that bad search link came up but my order was for the motor and resistor that THEY offered together:

http://www.partstrain.com/store/det...or/1999/Base/6_Cyl_3-dot-2L/21915-03-PLK.html

The wires didn't match so I returned the new blower motor, kept the new resistor and plugged it into the old blower motor because...

the wire of the original part (i.e the blower motor that was already in the car) has two cylinder-shaped male ends inside a plug that fit into two female tubes inside the plug to the car. The wires attached to the replacement motor are separate and have different plugs that do not fit into the car's (female tubes) plug.

I want to order part(s) that match in power and connection/fit.Sorry for all these posts. Thanks.
 
#29 ·
OK. So:

1) The regulator in your car was already a porcupine
2) When you ordered the blower + porcupine the blower came with separate wires but not a 2 pin connector but the blower you had already 2 pin plug
3) you returned the blower, and used the existing blower with the adapter harness and the porcupine, and it worked.
4) Now the porcupine does not seem to work and you want to replace it
5) You want to order the correct porcupine

Is this correct ?

Please see attached for illustration, (not a suggestion for you to purchase)



As you can see the 3 pin connector goes to the porcupine.

In the old blower motor, the flat iron type regulator is mounted at the metal bottom of the blower.
 
#30 ·
See photos!

Is this correct ?
1) The regulator in your car was already a porcupine YES
2) When you ordered the blower + porcupine the blower came with separate wire... YES...
...but not a 2 pin connector but the blower you had already 2 pin plug... YES THE WIRE FROM
OLD AND CURRENT BLOWER TO RESISTOR HAS A 2 PIN PLUG THAT SEEMS TO FIT THE PORCUPINE RESISTOR. THERE IS ALSO A (POWER?) WIRE WITH 3 FEMALE TUBES INTO WHICH GO 3 MALE PRONGS FROM THE RESISTOR
3) you returned the blower, and used the existing blower with the adapter harness and the
porcupine, and it worked. YES
4) Now the porcupine does not seem to work and you want to replace it YES IF THAT IS THE
SOLUTION
5) You want to order the correct porcupine
YES IF THAT IS THE SOLUTION
 
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