Yes, 419 is either the clutch coil, or the wiring to the coil from the controller.

With the engine off try turning the clutch (there is a 10 mm bolt in the center clockwise). It should turn a turn or two. If not, the compressor is seized.
Then start the engine, with the a/c on. you should see the compressor clutch engaging (turning with the pulley). If not, it confirms the 419 code.

There is no need to "palm read" when the writing is on the wall .

 

How can the system be at 12 bar with compressor seized?

Sixto
98 E320 wagon 197K miles

 

compressor does not appear to be seized, i can turn it by hand (too little effort?).

i also notice the front part (where the bolt is) is stationary with the a/c on and engine running.

 

That sounds like a wiring issue to the coil. Typically if the compressor is seized, the coil thermal fuse opens up, and you will have some burning smell due to belt friction at that instant.

Then you need to remove the connector at the top of the compressor (with everything turned off, of course, and measure the resistance between the body of the compressor and inside the black connector where the controller wire is plugged into. It should read few Ohms. This is to test the wiring between the coil and the black connector on the compressor (sometimes it gets corroded).

To answer Sixto's question, there is really no difference between a seized compressor and a compressor with a bad coil, as in both cases, the compressor will not turn. Why is there 12 bars ? 1) system is grossly overcharged, or 2) the compressor clutch fault is intermittent. or 3) refrigerant pressure sensor is flaky (thus code 232)

 

yikes! it's oily and hot and very tight down there, think i'll wait until things cool...

is what i'm looking for the black round connector in this compressor pic?

on a side note, some of the insulation of the wires to the headlights is disintegrating. i haven't yet seen it elsewhere but, if it becomes more widespread, could this be the end for my poor w210?

 

Yes. There is a mating connector from the controller (via the fuse box cross-connect). You need to remove the connector very gently, holding from the connector body. Sometimes the wiring in the compressor end is damaged, and sometimes the wiring from the controller (collapsed engine mounts at some point may put strain on the wire).

The headlight wiring, you can repair (substitute wiring, soldering, heat-shrink tubing). or you can buy a headlight harness for $25 or so. Search EBay.

 

ok, thanks. i'll give that a try later tonight or in the cool of tomorrow morning and report back.

as always, your help is much appreciated! 🍻

 

wow, it's tight in there. after moving the washer reservoir aside, i think i'm able to see what i need to unplug. have a look at the pic (sorry for the poor quality), is my screwdriver pointing at the right part? on closer inspection of the compressor pic above, i think the line of separation is just above (to the right in the pic) the screwdirver tip?

the wire still appears to be attached to the male end of this plug. i was hoping i could just poke one of my multi-meter probes in to get a reading but, no luck. i'm checking ohms between what's inside the female end and compressor body, correct?

it appears the only way to reach this on the v8 is from below (blind). i'll push the car out of my cramped garage to get up on stands and have a go from underneath after we run a few errands (using another car).

yes, it's very messy in there. i also need to redo the valve covers / breather...

 

Yeah, that is the connector, and that is the connector on the compressor you need to take the measurement (after you remove the wiring from the controller which can be a bit challenging).

BTW, You took the above readings with the engine off, right ? Then the voltage reading is normal. Never rely on the voltage readings from the climate controller. Always check the battery voltage across the battery terminals or the charging points under the hood (with and without engine running).

 

Another AC problem with low voltage. How many miles on alternator brushes?
Fix the charging problem before worrying about AC.

 

yes, the readings in the original post were engine off, key #2 position.

battery voltage (checked at the terminals in the engine bay with a trusted digital multi meter) is 12.6 off, 14.18 running.

where's the controller i also need to disconnect? i can't simply pull that round male end out and put one probe in to the open end left on the compressor?

kajtek - as far as i know, it's still the original alternator with 270+k miles.

 

where's the controller i also need to disconnect? i can't simply pull that round male end out and put one probe in to the open end left on the compressor?

Yes, I meant the removal of the black plug is challenging especially if you cannot easily reach it.

Here is the drawing for the climate control system.

N22 at the top is the climate controller (the unit in the dash with the buttons and display). Pin 25 is the compressor coil control signal wiring which first goes to the fuse panel at the drivers side, and then cross-connected to a wire that goes to the compressor A9. The X1 is the black connector. You remove the wiring and insert the multimeter lead tip into it and then the other lead is connected to the chassis of the compressor or chassis metalwork around there.

There does not seem to be anything wrong with the battery or the charging system. If there were, you would know about it in other ways (like the ABS/BAS/ASR indications).

 

ok, car's in the air, driveway beneath is cooling. after retrieving my wife's now repaired cell phone, i'll remove the plastic under engine tray and try to remove that plug.

muchas gracias!

as an aside, the cell repair shop's inside an asian (mostly vietnamese) mall in the "little saigon" district of san jose. we observed a reduced amount of indoor shoppers - mostly masked & a fair amount of outdoor diners... dammit, that food smells good! i sooo wanted to sit down and pretend there's no pandemic... and, it's warm out, the eye candy's pretty nice too...

 

i don't seem to get any readings between the plug and compressor body.

it's quite difficult to know if the probe was actually touching the single metal pin deep in the female end of the plug. i ended up poking a stiff braided wire, slightly splayed, at least as deep as the male end of the plug while having my wife read the ohm meter from above - no readings unless i connected the probes through my various alligator clips and wires.

i wish i could be absolutely confident i was making contact down there but, feel this was the best i could do without removing the compressor (that appears to be a questionable possibility, even from below, ha ha!)

 

Go to the pick-n-pull on Commercial St. The one on Monterrey Rd. closed for good. Remove the connector from any V6 or V8 210 (maybe any MB of comparable vintage), cut the connector with as much wire as you can. Now you have a test connector to check the clutch or force the clutch to engage for refrigerant charging.

Sixto
98 E320 wagon 197K miles

 

Have a look at this thread:
2000 E320 No AC (broken clutch wire)

Then this.

Photo DI'M'- A/C Clutch Coil R/R

If you do not have something less than 5 Ohms on the compressor body and the connector, either the coil is open or the connection to the coil (as shown in the second thread).

You can insert a very fine bare wire into the male connector and insert it into the female on the compressor. The wire will get squeezed between the pin and the socket (male side). If you leave enough pigtail, it will allow you to read the resistance on the pin.

The other option is to insert a needle into the wiring between the compressor connector and the coil (at the top of the pulley) and measure between the needle and the compressor body.

 

thanks for those links, very instructive. g-amg in his usual excellent write up was referring to his '98 e320, correct?

i'm finding my working quarters are so much more tight thanks to that big v8... i don't see how to access the top of the compressor. if i removed the belt, could the compressor swing downwards? also unclear at this point is if i'd be able to access the snap rings at the front of the clutch without removing the radiator.

i plan to take tabijan's excellent advise to get a plug from pick-n-pull and try again later today.

 

if i removed the belt, could the compressor swing downwards?

Having done the E55 swap, so memory is fresh.

Assuming healthy motor mount, then yes, you can shove forward the AC when unbolted 3 bolts and disconnect belt....few inches only, but its all you need.

Space is tight, but doable.

 

2.6 ohms between the compressor clutch plug and housing is the reading i get with my cobbled together tool (thanks tabijan!). here's a pic of that setup and what else i got done under the hood.

while at pick-n-pull, i succumbed to mission creep... the '97 e420 that yielded the compressor clutch plug 1) also had a pristine windshield washer reservoir (5 instead on 5.5 liters but a screw top & drain hose!) to replace my brittle yellowed original with cracked lid and broken mount. 2) can one man ever have enough bosch maf's in reserve? 3) a passenger mirror "frame" (?), mine no longer holds tight against it's stops... 4) i attempted to remove some drilled (holes chamfered) front rotors but, didn't have the proper wrench. rusty but, only the slightest of edge felt on the inboard side. i'm contemplating returning with penetrating spray and the proper tools for those... where are the black market "helpers" (friendly mexican guys with tools) when you need 'em?

i humbly await your thoughts on next steps.

deplore, i wish you were local. i'd totally try to help / wipe your brow / stay out of the damn way, just to try to sponge up some of your knowledge and experience!

all in all, not a bad day off. now, i'm gonna ride my bike with the dogs to the park and drink beer! 🍻 😋

 

If you have a 12V source apply it to the cable you just got and chassis ground see if the clutch engages (key in your pocket). If it does, then the problem is in the wiring, likely in the connector to the compressor from the controller.

You can check the continuity by measuring the resistance between the connector terminal (inside the black male plug) and somewhere along the cable that you need to pierce with a needle. If open, it is in the connector, and you need to repair the connection or replace the connector with the JY one with its pigtail, somewhere convenient to work around. If you have continuity, then the open is somewhere else.

 

not so confident on electrical, not sure i really understand your instructions...

can i connect a small wire from the 12v battery post on the nearby fender well to my "testing plug" - this is the "apply 12v source"?

the next part i'm not clear on - "and chassis ground" - do i need to ground the compressor body by running a wire from anywhere metallic on it to somewhere solid and metallic on the car body?

when i'm doing so, i'm assuming i'll hear some sort of click or other indication the clutch is engaging?

it's back to work for me the rest of the week, might be the weekend before i get back to this. thankfully, the bay breezes have resumed.

 

You can apply 12V from the battery charging post under the hood, but I would use a 10 to 15 amp fuse in series, just in case you accidentally short the wire to ground (so the fuse will open to clear the short).

The compressor clutch coil is wired to the compressor body at the top of the compressor (the other wire goes to the black female connector). The compressor is also bolted to the engine metalwork which is bolted to the chassis. So, all you need to do is to connect the compressor wire to the battery charge stud with a fused wire. You should hear the clutch engaging. Also check that the clutch is not turning when engaged (clutch clearance adjustment / weak coil check).

 

thanks for the clarification, i'm now confident with this next step!

 

If you test with the engine running, you should see the compressor spinning when you apply 12v. If you test with engine off, you won’t be able to spin the compressor by hand against the belt when you apply 12v.

Sixto
98 E320 wagon 197K miles

 

if this works, i can see me riggin' some sort of appropriately janky switch to convert that clutch to manual operation?

perhaps something like this?

the purists won't be happy...

 

update; per mr boca's suggestion, i applied 12v to the compressor clutch (round plug on the housing). nothing, nada. this with the engine off, using the positive post on the driver's fenderwell. i could still spin the clutch by hand.

i redid the resistance test to make sure my plug was making contact and got 4.6 ohms between the wire coming off my plug and the compressor housing.

i'm guessing this means the compressor clutch is kaput and needs to be replaced?

 

That is very strange.
Measure the resistance between the compressor cable and the chassis ground (the grounding stud close to the charging point under the hood). The coil terminal is bolted to the compressor body which in turn is bolted to the engine.

There is a possibility that the coil is energized but not enough to pull the clutch plate (too much clearance). In some cases, tapping the clutch with a bar towards the compressor encourages it to stick to the pulley surface .

But you need to make sure that the compressor is well-grounded.

Looking at your post #20, you measured 2.6 Ohms, NOW you say it is 4.6 Ohms. Anything changed ?

 

only thing i can think of is this time, the wire was longer with a 10 amp fuse. i do notice the ohms jumps around until i have the probe on the body securely, past all the grime...

in the picture, i tested at the exposed wires at the bottom of the pic. the connector at the end of the curled wire, fit pretty well into the positive post on the fender well. i used my test light to be sure i was sending 12 volts at least as far as the last twisted splice before the compressor plug.

i like the "tap it with a bar" next step, just my speed!