W210 Compressor clutch slipping? - PeachParts Mercedes-Benz Forum

deltajetfixer · #1 08-28-2006, 05:36 PM

I don't have much experience with repairing air conditioning but here's the story:

Today I noticed the lack of cold air from the vents when the AC was "on". Plenty of airflow, just no cooling.

Auxiliary fans are not coming on nor is the compressor engaging.

Found the info on obtaining the Actual Values and came up with reasonable numbers (range from 95-111 degrees F)for all the temperature sensors. The refrigerant pressure reads "08" which seems legitimate with no compressor operation.

Codes pulled are:
B1419 Electromagnetic clutch
B1226 In-car temperature sensor
B1234 Sun sensor

Here's the wierd thing. The compressor clutch is producing a burned smell with the climate control set to OFF. You can hear it and see it barely making its way around in rotation about an 1/8th of an inch at a time per revolution. It sounds like a dragging brake disk. I can also move the clutch by hand quite easily.

I just replaced the coolant, fan clutch, aux fan belt, and main belt and the car was operating fine until this afternoon.

Oh yeah, if anyone can tell me where the fuse is for the clutch, I'd really like to know about it. I've been through all three fuse boxes and can only find one labled Blower Motor AC.

Ideas? Thanks in advance!

Gilly · #2 08-28-2006, 06:40 PM

Disconnect the wires going to the compressor to disengage the clutch. Try to turn the inner part of the pulley (on the front of the clutch) and see if the compressor is seized. Is the "EC" light on on the AC control panel?
Gilly

Matt L · #3 08-28-2006, 06:47 PM

A dragging clutch would heat up the pully. That could blow the thermal fuse which is built into the clutch.

See if you have continuity across the clutch windings.

deltajetfixer · #4 08-28-2006, 06:59 PM

Quote:

Originally Posted by Gilly

Disconnect the wires going to the compressor to disengage the clutch. Try to turn the inner part of the pulley (on the front of the clutch) and see if the compressor is seized. Is the "EC" light on on the AC control panel?
Gilly

I've got the car off so I'm assuming that there's no current going to the clutch.

Clutch turns freely. "EC" light is not stuck on. It illuminates when pressed and goes out when pressed again.

deltajetfixer · #5 08-28-2006, 07:06 PM

Quote:

Originally Posted by Matt L

A dragging clutch would heat up the pully. That could blow the thermal fuse which is built into the clutch.

See if you have continuity across the clutch windings.

I'd LOVE to test the continuity but it'll have to wait until the morning.It would REALLY be easy if there was an associated fuse for the sucker but I can't find it!!! Probably controlled by some computer somwhere.

I'm aware of the thermal fuse. From what I've read in my copy of WIS, it seems to indicate that a seized compressor would generate enough friction to set it off.

This thing is slipping ever SO slightly. I fear with the new engine fan clutch I installed a week ago that the underhood temps have been reduced to the point where this tiny amount of slippage won't melt the thermal fuse! I can rotate the clutch easily by hand so I doubt the compressor's seized.

I'm just curious as to why a compressor clutch would fail in this manner? Maybe a return spring is broken?

Would you happen to know if it's possible to replace just the clutch on this beast without possibly removing the refrigerant lines? Clutch is about $150 versus $600 for the compressor. Only thing holding me back in figuring out how I would hold the compressor shaft still to remove/install the clutch. WIS doesn't detail the procedure.

Gilly · #6 08-28-2006, 10:22 PM

OK, there is the outside of the pulley, the part the belt spins, and the inside of the clutch, the part that rotates the compressor when the clutch is engaged. You just need to hold the inside part of the clutch and I believe you'll see a nut in the center which is removed to take off the clutch and pulley assembly, so no need to take off lines and can be done on the car. Not sure what's used to keep the inside of the clutch from rotating, I believe that nut is pretty low-torque, may be able to hold it by hand.
Gilly

deltajetfixer · #7 08-29-2006, 10:50 AM

Quote:

Originally Posted by Matt L

A dragging clutch would heat up the pully. That could blow the thermal fuse which is built into the clutch.

See if you have continuity across the clutch windings.

OK. I got to the electrical connection at the clutch windings. They are OPEN. Control voltage to the windings with the panel showing OFF is @6.5-7.0 volts. With panel ON, voltage goes to 13.5.

So here's my proposed plan of attack and please critique anything you find unnecessary. I plan on:

1) Buying a new clutch and installing it. I figure I can keep the shaft from rotating via a strap wrench. The bolt in the center of the clutch looks to be @10-12mm so I figure it's not on that tight.

2) Since the radiator has to come out for optimum visibilty and working ease I'm also considering replacing the waterpump and thermostat/thermostat housing as preventive maintenance. Car has 91500 miles.

Comments PLEASE!

deltajetfixer · #8 08-29-2006, 10:52 AM

Quote:

Originally Posted by Gilly

OK, there is the outside of the pulley, the part the belt spins, and the inside of the clutch, the part that rotates the compressor when the clutch is engaged. You just need to hold the inside part of the clutch and I believe you'll see a nut in the center which is removed to take off the clutch and pulley assembly, so no need to take off lines and can be done on the car. Not sure what's used to keep the inside of the clutch from rotating, I believe that nut is pretty low-torque, may be able to hold it by hand.
Gilly

Agreed. Diameter of bolt appears to be less than 13mm.

Have you ever heard of a clutch failing in this manner?

Gilly · #9 08-29-2006, 05:19 PM

Can't think of one right offhand, no. On the clutches I saw more failures on air pump clutches than AC for some odd reason. You need to find out the clearance for the clutch and make sure that gets set up correctly. Shims are small, around the shaft area. IIRC it's kind of opposite what you would think, meaning more shims=tight, less=looser.
Gilly

Eltee · #10 08-29-2006, 09:27 PM

I think the coil is held on by a large snap ring located inside the magnet. You will see it once you take off the front of the clutch. I don't think you will have to take the radiator out to do the job.

samiam4 · #11 09-02-2006, 01:43 AM

Gilly,

So do you shoot for nominal or to the large side of the tolerance? Mine is a little less than the 0.5mm nominal. It's plus or minus 0.15 mm.

YOur comment makes me wonder if I should shoot for 0.6mm? Can I find shims on a holiday weekend for a Nippendenso 10P15 Compressor?

Michael

deltajetfixer · #12 09-08-2006, 01:25 PM

Quote:

Originally Posted by Eltee

I think the coil is held on by a large snap ring located inside the magnet. You will see it once you take off the front of the clutch. I don't think you will have to take the radiator out to do the job.

Thanks to all who contributed.

Due to time constraints and lack of a third vehicle I wasn't able to take any pictures. The procedure however, is pretty straightforward:

To replace the clutch:

1) VERIFY that your compressor isn't "shelled out".
2) Remove the belt from the compressor pulley and see if it rotates by hand. It should do so quite easily. My pulley had an extraordinary amount of play in it due to a failed bearing.
3) Check the Actual Values display on the A/C control Panel or hook up some gauges to verify that there is an appropriate amount of freon in the system.
4) Perform continuity check on the electromagnetic coil. Mine was OPEN.Also check that you can get power TO the coil from the associated wire.
5) Remove fan shroud, engine driven fan, serpentine belt, and sheetmetal crossmember in front of radiator.
6) Remove auxiliary fans and horn.
7) Remove front lower splash shield.
8) REMOVE RADIATOR! I tried doing this without doing so and it just didn't work. I left the hoses connected to the radiator. You're going to have to break the two ATF lines loose as well as lift the condenser UP on the left and right sides as it sits in two "L' brackets on either side of the radiator. You'll also need to remove two 10mm bolts at the bottom front of the intercooler attaching to the bottom front of the radiator.
9) Use a strap wrench to hold front of compressor and remove 10mm bolt holding front hub on. It'll come off quite easily. BE SURE to put one hand underneath to catch shims.IF you lose one, don't panic as 6mm washers work quite nicely plus you get three spare of varying thicknesses in the replacement clutch kit.
10) Use a GOOD pair of external snapring pliers to remove first snapring then remove pulley. You get new snaprings in the kit so feel free to destroy the old. A good mirror is a necessity here and in the next step.
11) This next snapring is a *****! It's nestled about ONE INCH inside the coil cavity. This is why the radiator had to come out as you're going to approach it head on with straight tip external pliers. I had to cut the handles down on mine. Cut down ONLY as much as you barely need as your leverage will suffer. Maybe someone has some really long 90 degree tips but I couldn't find any.
12) Remove screws holding coil ground and power wires and remove coil. My coil was BAKED!
13) Reverse steps to reinstall.
14) When you get to setting the airgap (instructions in kit specify 0.45mm, +0.15mm or -0.10mm) be sure you check it AGAIN after reinstalling the serpentine belt. The preload affects the clearance. I set mine at 0.51mm. Also be sure your feeler gauge is between the friction material on the pulley and the clutch hub. The first time I did this, I set it too close (didn't take into account the friction material, I just measured at the edge) and burned the friction material off the pulley. This caused me to have to buy a new clutch and just replace the pulley and hub. I managed this without having to remove the radiator again.

The clutch is available from Phil for $148. He got me mine (the second one) in two days.The Stealer wanted $750...just for the clutch!!! God knows how much they would've charged to do it! This is the first time I've ever done a compressor clutch. Hopefully it'll last me another 7 years.

Total ATF lost was about one pint. I elected not to replace the waterpump and thermostat as preventive maintenance. Only thing left to do is clear the DTC's from the A/C panel.

nhdoc · #13 09-08-2006, 01:54 PM

Just wondering delta...it seems like it might have been easier to just remove the compressor and change the clutch on the bench rather than mess with moving all the stuff in front of it out of the way.

I realize this would mean having to evac and recharge the system and you'd spend a few $$$ on refrigerant but still I have seen the procedure for the R&R of the compressor and it looks like it can be done in about an hour or so...how long did it take to do it your way?

It's weird that MB charges more for the clutch kit than an entire rebuilt compressor sells for. Even their list price for the entire compressor is only $900, or $190 more than the clutch, but I don't know if that is rebuilt or new for $900.

deltajetfixer · #14 09-08-2006, 03:25 PM

Quote:

Originally Posted by nhdoc

Just wondering delta...it seems like it might have been easier to just remove the compressor and change the clutch on the bench rather than mess with moving all the stuff in front of it out of the way.

I realize this would mean having to evac and recharge the system and you'd spend a few $$$ on refrigerant but still I have seen the procedure for the R&R of the compressor and it looks like it can be done in about an hour or so...how long did it take to do it your way?

It's weird that MB charges more for the clutch kit than an entire rebuilt compressor sells for. Even their list price for the entire compressor is only $900, or $190 more than the clutch, but I don't know if that is rebuilt or new for $900.

It took me @4 hours start to finish including refilling/rebleeding the coolant system.
The air conditioning was working flawlessly prior to this event and I didn't want to risk creating other problems, namely leaks. I'm not set up with A/C service equipment nor do I have any experience with it. I also HATE to have other folks work on my car.

My labor is basically "Free" so I saw it as an opportunity to return the vehicle to its former status quo with minimal cost on my part. Besides, I would've STILL burned the clutch up doing it the way you suggested, as I was going for the literal "air gap" rather than the friction lining/hub clearance.

I do enjoy working on the car. Would've been nice to have gotten away with it for $150 versus $300 but it beats the Hell out of what The Stealer would've charged! Live and learn.

nhdoc · #15 09-08-2006, 03:36 PM

Yeah, if you don't have the gauges and vacuum pump then your way would have been best...sooner or later you will need them anyway though