Re: [MBZ] Weeping Servo...Weeping Driver
$195 plus SH. Amps are $69 or $95. Bob Rentfro - Original Message - From: Barry Stark [EMAIL PROTECTED] To: Mercedes Discussion List [EMAIL PROTECTED] Sent: Saturday, April 15, 2006 4:30 PM Subject: Re: [MBZ] Weeping Servo...Weeping Driver I believe George charges $100 to rebuild an aluminum bodied servo. I bet if you follow Dan's list you will find the problem. George may be able to tell you right away what the problem is. You might give him a call. Barry Yes it is. It served me well last summer. What do you reckon Murphy would charge for a rebuild? ___ http://www.striplin.net For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net
Re: [MBZ] Weeping Servo...Weeping Driver
Thanks Dan... This is wonderful. Bob Rentfro - Original Message - From: Dan Sandy Steadman [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, April 14, 2006 8:42 AM Subject: Re: [MBZ] Weeping Servo...Weeping Driver Re: [MBZ] Weeping Servo...Weeping Driver Bob writes: I suppose I need to devise a systematic troubleshooting methodology for this and get it right this year. Bob, Here is some information I have accumulated over the years of working on this system: If the ACC Servo has been replaced with an aluminum body servo, make sure that you used nylon attachment bolts, and nylon washers to mount the servo, or you might encounter intermittent electrical problems with the servo. Everything in the ACC system is vacuum controlled through the ACC Servo. It is possible that a vacuum line came off or loose. The switch that turns on the fan is a vacuum actuated relay. This relay (or vacuum switch) is located just above the radio and behind the vertical switch assembly. It is the one on the far right side of the relay bank. Near this relay is a coil of green wire located near the passenger foot-well near the glove box. This coil of wire is a controlled vent for the vacuum system. Don't try to find a place to connect it - one end is plugged into a vacuum line; the other end is open to allow air to enter the vacuum system at a very slow rate. If this wire is missing, or has fallen out, the blower will only run in defrost. (The vent line is a German engineers idea of a practical joke). Defrost mode, by the way, bypasses all of these circuits. Assuming that the vacuum is OK, check the servo and servo control system. This system consist of a temperature sensing resistor loop, an ACC control amplifier (located behind the glove box), and the dreaded servo (located under the hood, to the right on the engine). The temperature is sensed/controlled by a sensor chain. The sensor chain consists of a series of resisters; the ambient air temperature sensor (located on the firewall just behind the engine), the temperature dial, the in-car temperature sensor (located in the dash in the right hand speaker grill, and the resister in the servo. If there is a problem in the resistor chain, it is likely with the sensor in the dash. This sensor work by drawing in car air through a tube connected to the blower. If this tube is deteriorated, replace it with a piece of water pipe foam insulation. Generally, a deteriorated sensor pipe will cause erratic temperature control. The temperature dial resister can have a dead spot near the end. To check out the resister chain, 1. Remove the ACC amplifier (located behind the glove box) and connect a ground to pin 3 of the connector plug. 2. At the servo electrical connector, connect an OHM meter between pins 1 and pin 2 on the left of the connector. 3. Place the temperature wheel at max (85 degrees) and the resistance should be between 2.2K ohms, and 4.7K ohms. 4. Place the temperature wheel at 65 degrees, and the resistance should be between 1K ohm and 3.5 K ohms. When you finish, re-install the amplifier. If the circuit is open at any place in the resistor chain, the result is heat. If the chain is OK, then the problem might be the amp. To check the amplifier, connect a voltmeter between pins 1 and 7. With the ignition switch in the on position, the voltage should be about a volt. Move the temperature wheel from cold to hot. The voltage should increase to about 5 volts, the servo motor should move, and when the servo finds it home, the voltage will drop back to about a volt. If it does not vary, then the amp is bad. If you listen to the servo, you should be able to hear the servo motor running to find the new position. To check the motor in the servo, disconnect the electrical connectors on the servo, and connect 12 volts between pins 4 and 5. The motor should run in one direction and stop. Reverse the voltage and it should run in the other direction. If it runs, only run it momentarily in each direction. Pin 1 on the connector is on the left (towards the engine) side of the servo. There is an inline fuse, located in the relay box on the fender, as I recall. The in-line fuse powers the amplifier when the car is turned off to run the servo to a parked position. The purpose of the parked position is to avoid having the system start up where it was when you last turned off the car. If the fuse is in there and the servo is operating properly, the servo will run to PARK and shut itself off after you turn off the car. If the servo is seized, the servo will run the battery down overnight for no apparent reason - because the motor in the servo is always trying to move the servo to a parked position and can't, thus, the system runs the battery down trying to park the servo all night. It does not hurt to leave the inline fuse disconnected. The system will work correctly, but the servo will not park. For most people, this is generally
Re: [MBZ] Weeping Servo...Weeping Driver
I believe George charges $100 to rebuild an aluminum bodied servo. I bet if you follow Dan's list you will find the problem. George may be able to tell you right away what the problem is. You might give him a call. Barry Yes it is. It served me well last summer. What do you reckon Murphy would charge for a rebuild?
Re: [MBZ] Weeping Servo...Weeping Driver
Re: [MBZ] Weeping Servo...Weeping Driver Bob writes: I suppose I need to devise a systematic troubleshooting methodology for this and get it right this year. Bob, Here is some information I have accumulated over the years of working on this system: If the ACC Servo has been replaced with an aluminum body servo, make sure that you used nylon attachment bolts, and nylon washers to mount the servo, or you might encounter intermittent electrical problems with the servo. Everything in the ACC system is vacuum controlled through the ACC Servo. It is possible that a vacuum line came off or loose. The switch that turns on the fan is a vacuum actuated relay. This relay (or vacuum switch) is located just above the radio and behind the vertical switch assembly. It is the one on the far right side of the relay bank. Near this relay is a coil of green wire located near the passenger foot-well near the glove box. This coil of wire is a controlled vent for the vacuum system. Don't try to find a place to connect it - one end is plugged into a vacuum line; the other end is open to allow air to enter the vacuum system at a very slow rate. If this wire is missing, or has fallen out, the blower will only run in defrost. (The vent line is a German engineers idea of a practical joke). Defrost mode, by the way, bypasses all of these circuits. Assuming that the vacuum is OK, check the servo and servo control system. This system consist of a temperature sensing resistor loop, an ACC control amplifier (located behind the glove box), and the dreaded servo (located under the hood, to the right on the engine). The temperature is sensed/controlled by a sensor chain. The sensor chain consists of a series of resisters; the ambient air temperature sensor (located on the firewall just behind the engine), the temperature dial, the in-car temperature sensor (located in the dash in the right hand speaker grill, and the resister in the servo. If there is a problem in the resistor chain, it is likely with the sensor in the dash. This sensor work by drawing in car air through a tube connected to the blower. If this tube is deteriorated, replace it with a piece of water pipe foam insulation. Generally, a deteriorated sensor pipe will cause erratic temperature control. The temperature dial resister can have a dead spot near the end. To check out the resister chain, 1. Remove the ACC amplifier (located behind the glove box) and connect a ground to pin 3 of the connector plug. 2. At the servo electrical connector, connect an OHM meter between pins 1 and pin 2 on the left of the connector. 3. Place the temperature wheel at max (85 degrees) and the resistance should be between 2.2K ohms, and 4.7K ohms. 4. Place the temperature wheel at 65 degrees, and the resistance should be between 1K ohm and 3.5 K ohms. When you finish, re-install the amplifier. If the circuit is open at any place in the resistor chain, the result is heat. If the chain is OK, then the problem might be the amp. To check the amplifier, connect a voltmeter between pins 1 and 7. With the ignition switch in the on position, the voltage should be about a volt. Move the temperature wheel from cold to hot. The voltage should increase to about 5 volts, the servo motor should move, and when the servo finds it home, the voltage will drop back to about a volt. If it does not vary, then the amp is bad. If you listen to the servo, you should be able to hear the servo motor running to find the new position. To check the motor in the servo, disconnect the electrical connectors on the servo, and connect 12 volts between pins 4 and 5. The motor should run in one direction and stop. Reverse the voltage and it should run in the other direction. If it runs, only run it momentarily in each direction. Pin 1 on the connector is on the left (towards the engine) side of the servo. There is an inline fuse, located in the relay box on the fender, as I recall. The in-line fuse powers the amplifier when the car is turned off to run the servo to a parked position. The purpose of the parked position is to avoid having the system start up where it was when you last turned off the car. If the fuse is in there and the servo is operating properly, the servo will run to PARK and shut itself off after you turn off the car. If the servo is seized, the servo will run the battery down overnight for no apparent reason - because the motor in the servo is always trying to move the servo to a parked position and can't, thus, the system runs the battery down trying to park the servo all night. It does not hurt to leave the inline fuse disconnected. The system will work correctly, but the servo will not park. For most people, this is generally not a problem. While you are working around the servo, check the operation on the aux water pump located beside the servo. The auxiliary water pump tends to short when they stop working. If the pump is bad
Re: [MBZ] Weeping Servo...Weeping Driver
Bob Rentfro wrote: My wretched ACC servo has crusties built up around its base. Is it toast? Here is why I ask: Since it was 93 yesterday, I tried the AC (for the first time since Feb) and it works fine (50 degree air out of center vents) for about 15 minutes then it somehow fails in like a mid position where I get a whisper of cool air out of each cabin orifice (floor, defrost, sides, middle). As an aside, I do need to replace my thermostat...I believe it's stuck open since I can't get above 135 degrees ever. Does this effect the operation of the stickin' servo from hell? I was going to take the 300D to Cal tomorrow to pick up the girls but I don't think I want to hear 400 miles of this AC isn't working again? I still think there is a room somewhere in one of Chrysler's office buildings where they sit and laugh about giving this technology to MB. The stuck thermostat only doubles (or a bit more) engine wear and reduces fuel economy. It has NO effect on AC operation. If there is remnants of fluid residue that's leaked from the servo, then the servo needs to be replaced. Marshall -- Marshall Booth (who doesn't respond to unsigned questions) der Dieseling Doktor [EMAIL PROTECTED] '87 300TD 182Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi, '84 190D 2.2 229Kmi (retired)
Re: [MBZ] Weeping Servo...Weeping Driver
My wretched ACC servo has crusties built up around its base. Is it toast? They aren't supposed to leak. When they do, fluid gets into bad places. Sorry, dude! Don't cry for me get the checkbook... [Evita] I still think there is a room somewhere in one of Chrysler's office buildings where they sit and laugh about giving this technology to MB. Not anymore. Why do you think Chrysler was bought and submerged? Revenge for the ACC! -- Jim
Re: [MBZ] Weeping Servo...Weeping Driver
In a message dated 4/13/2006 8:57:34 A.M. US Mountain Standard Time, [EMAIL PROTECTED] writes: My wretched ACC servo has crusties built up around its base. Is it toast? Here is why I ask: Since it was 93 yesterday, I tried the AC (for the first time since Feb) and it works fine (50 degree air out of center vents) for about 15 minutes then it somehow fails in like a mid position where I get a whisper of cool air out of each cabin orifice (floor, defrost, sides, middle). As an aside, I do need to replace my thermostat...I believe it's stuck open since I can't get above 135 degrees ever. Does this effect the operation of the stickin' servo from hell? Bob, Is that the aluminum housing servo I sold you a while back? I am surprised it is leaking at all! I think George Murphy can rebuild that for you and give you a lifetime warranty. As to your current problem, it sounds like your blower motor is dying, probably very worn brushes. George has replacements for those too, but this isn't going to help you by tomorrow. What happens when the blower dies and you push defrost? Defrost should bypass the servo and put the blower to full speed using a relay. If the blower only runs in defrost, it could be a bad servo. It may be that you have an intermittent pushbutton assy. I understand they can be resoldered, once removed. I have also seen the push on connectors, on the back of the pushbutton assy, melt down. That would explain the failure after a few minutes of heating up, too. I still vote for the blower motor brush failure though. Regards, Jim Friesen Phoenix AZ 79 300SD, 262 K miles 98 ML 320, 141 K miles
Re: [MBZ] Weeping Servo...Weeping Driver
Mr. Jim typed: Is that the aluminum housing servo I sold you a while back? Yes it is. It served me well last summer. What do you reckon Murphy would charge for a rebuild? What happens when the blower dies and you push defrost? Defrost should bypass the servo and put the blower to full speed using a relay. If the blower only runs in defrost, it could be a bad servo. After it fails and I mash the defrost, the blower comes back to life and I get loads of air out the defrost vents and whispers of air everywhere else. Somewhere I have a pushbutton assembly I picked up somewhere. Perhaps I'll swap it out and see what happens. I suppose I need to devise a systematic troubleshooting methodology for this and get it right this year. Bob Rentfro '77 300D, 151K Litchfield Park, AZ
Re: [MBZ] Weeping Servo...Weeping Driver
Bob Oh the old servo. Once a week, summer winter or when ever put Auto II system on defrost and turn the temp reostate to full heat 85 degrees let it run for about 5 to 10 minutes. This is the best maintenace for these. Opens the unit up full and helps to keep her from sticking. I have run these servos with minor weeps for lots of miles. Check level in radiator every few hundred miles when warm or cold. The servo I believe is independent of the cooling water temp and works visa vi the vacuum system to modulate up and down (open and close) depending on the setting on the reostate and the ambient air temp in the car. I could be wrong but have spent some time trouble shooting this in the past in my 1977 300D Of course if your jacket water is only 135 degrees heat might be a propblem. Tom Scordato - Original Message - From: Bob Rentfro [EMAIL PROTECTED] To: Mercedes mailing list [EMAIL PROTECTED] Sent: Thursday, April 13, 2006 11:56 AM Subject: [MBZ] Weeping Servo...Weeping Driver My wretched ACC servo has crusties built up around its base. Is it toast? Here is why I ask: Since it was 93 yesterday, I tried the AC (for the first time since Feb) and it works fine (50 degree air out of center vents) for about 15 minutes then it somehow fails in like a mid position where I get a whisper of cool air out of each cabin orifice (floor, defrost, sides, middle). As an aside, I do need to replace my thermostat...I believe it's stuck open since I can't get above 135 degrees ever. Does this effect the operation of the stickin' servo from hell? I was going to take the 300D to Cal tomorrow to pick up the girls but I don't think I want to hear 400 miles of this AC isn't working again? I still think there is a room somewhere in one of Chrysler's office buildings where they sit and laugh about giving this technology to MB. Bob Rentfro '77 300D 151K Litchfield Park, AZ ___ http://www.striplin.net For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net
Re: [MBZ] Weeping Servo...Weeping Driver
I have the exact same symptoms in my '83 300SD with a freshly resoldered push button unit. I'm interested now. ~Mr. Jim typed: ~ ~Is that the aluminum housing servo I sold you a while back? ~ ~Yes it is. It served me well last summer. What do you reckon Murphy would ~charge for a rebuild? ~ ~ What happens when the blower dies and you push defrost? Defrost should ~ bypass the servo and put the blower to full speed using a relay. If the ~blower ~ only runs in defrost, it could be a bad servo. ~ ~After it fails and I mash the defrost, the blower comes back to life and I ~get loads of air out the defrost vents and whispers of air everywhere else. ~Somewhere I have a pushbutton assembly I picked up somewhere. Perhaps I'll ~swap it out and see what happens. ~ ~I suppose I need to devise a systematic troubleshooting methodology for this ~and get it right this year. ~ ~Bob Rentfro ~'77 300D, 151K ~Litchfield Park, AZ ~ ~ ~ ~ ~___ ~http://www.striplin.net ~For new parts see official list sponsor: http://www.buymbparts.com/ ~For used parts email [EMAIL PROTECTED] ~ ~To Unsubscribe or change delivery options go to: ~http://striplin.net/mailman/listinfo/mercedes_striplin.net -- Luther KB5QHU Alma, Ark '83 300SD (231,xxx kmi) '82 300CD (159,222 kmi) '82 300D (74,000 kmi) needs MAJOR work
Re: [MBZ] Weeping Servo...Weeping Driver
On Thursday 13 April 2006 1:21, Bob Rentfro wrote: If the blower only runs in defrost, it could be a bad servo. It could also be that the circuit board gizmo behind the glove compartment has gone bad. I tried re-flowing the solder on mine, to no avail. Bob, I would recommend taking a drive to south PHX and visiting Dirty Harry. He will let you try used boards until you find one that works, and I think he charges $25 for the used ones. Lee
Re: [MBZ] Weeping Servo...Weeping Driver
Perhaps I will go see Dirty Harry... If I find a good board it will make my day. (Couldn't resist) Bob Rentfro - Original Message - From: lee [EMAIL PROTECTED] To: Mercedes Discussion List [EMAIL PROTECTED] Sent: Thursday, April 13, 2006 1:07 PM Subject: Re: [MBZ] Weeping Servo...Weeping Driver On Thursday 13 April 2006 1:21, Bob Rentfro wrote: If the blower only runs in defrost, it could be a bad servo. It could also be that the circuit board gizmo behind the glove compartment has gone bad. I tried re-flowing the solder on mine, to no avail. Bob, I would recommend taking a drive to south PHX and visiting Dirty Harry. He will let you try used boards until you find one that works, and I think he charges $25 for the used ones. Lee ___ http://www.striplin.net For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net
