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Premium Member
1998 E320 base sedan @ 160kmiles
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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.
 

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1998 e430
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437 Posts
Discussion Starter #22
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.
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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7,215 Posts
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).
 

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1998 e430
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437 Posts
Discussion Starter #24
thanks for the clarification, i'm now confident with this next step!
 

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1998 E320 wagon
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1,142 Posts
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
 

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1998 e430
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437 Posts
Discussion Starter #26 (Edited)
if this works, i can see me riggin' some sort of appropriately janky switch to convert that clutch to manual operation? :p

perhaps something like this? :LOL:

the purists won't be happy...
 

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1998 e430
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Discussion Starter #27
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?
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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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 ?
 

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1998 e430
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Discussion Starter #29
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! :sneaky:
 

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1998 E320 base sedan @ 160kmiles
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Don't forget to measure with the lowest Ohms scale. Also, as I mentioned between the car chassis and the coil wire.
 

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1998 e430
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Discussion Starter #31
my multi meter is digital, no hi / low scale. it's after i'd buttoned things up, i though to double check with a different meter...

i found many times, i'd get no reading with my test plug. i'd re-insert a few times and finally get a reading; 5.25 ohms between that and the negative post on the fenderwell. i tried bending the plug's female contact just a bit to insure better contact with that male pin at the bottom of the connector, didn't seem to have any impact.

when i was getting an ohm reading, i connected 12v and still nothing on the clutch. used a jack handle and hammer to lightly tap the compressor body and points on the fan clutch, still nothing.

couple possibilities come to my mind; the clutch is stuck open or there's an electrical connectivity issue?

think i'm going to call it a day under the hood, feeling just a bit frustrated with this one. 🏳

after getting a spouse hair cut (2nd time, she's pretty good!) i'm gonna clean fish tanks and then take the dogs for a bike / run (if the wildfire smoke's not too thick), better chance of reward for easy work there. 🐠:)

a big mahalo, mr boca! if there's anything i can do for you (perhaps a favorite charity?), i owe you plenty!
 

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Premium Member
1998 E320 base sedan @ 160kmiles
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7,215 Posts
Yes, it is frustrating. I happened to have a compressor, and I measured the resistance right from the connector to the case (after zeroing the resistance reading by shorting the lead tips to discount their resistance), and mine was 4 Ohms. Connected the battery supply and the clutch engaged.

If you know how to measure the current with your meter you can connect in series with the 12V supply (making sure that the current setting at or more than 10 amps), and measure the current. It should be around 3 amps. If significantly less than that, I think the wiring may have been damaged similar to G-AMG's case.

Have you done the resistance measurement on the original clutch wiring? Connect the meter lead at the connector socket, and pierce the blue wire with a needle. If it reads open, you can splice the JY connector with its pigtail to the existing wire.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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4,343 Posts
Thinking bad clutch here, either magnetic coil is defective with thermal fuse popped, but still somehow connected that voltmeter still reads it. Seen that in a few honda AC compressors.

You could try swapping the clutch and coils from a junkyard unit and see what's up, otherwise you're looking at replacement compressor.
 

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1998 E320 base sedan @ 160kmiles
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7,215 Posts
If it is the original old style compressor, I would not even bother with the clutch coil and clutch replacement. It is very likely either the compressor needs to be taken out, or a bunch of stuff in front, and above it. I would just replace the compressor.
 

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Outstanding Contributor , SDS Guru
1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG
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4,343 Posts
Depends on how easily it's possible to remove the clutch.... From pictures, it seems to be a single bolt, unknown how difficult it's going to be take out without a vice or a way to grab the pulley from spinning. The E320 engine bay is pretty spacious as it is, so were it up to me I'd at least attempt that, with the next action simply replacing the compressor if the clutch isn't easily removable.

In Honda's depending on compressor pulley behavior, I just replace the clutch and send it.
 

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1998 E320 base sedan @ 160kmiles
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7,215 Posts
The clutch part is not the problem. It is a 10mm bolt and easy to remove, and the clutch too (and not letting the shims inside to drop and disappear). It is the C- clip access to remove the pulley to reach the coil. It is a E430 so space is limited, and you need to have the right tool to reach the c-clip. Then if you are lucky, the pulley will come out without too much persuasion, using a flat lever. It can be done, but best done with the compressor removed , or at least clutch side turned up a bit. After the coil is replaced, you need to make sure the clutch clearance is just right. Outside the car, it would take 15 minutes or so. Then, 6 months later, the old and tired compressor leaks from the front seal :eek:.
 

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1998 e430
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Discussion Starter #37
just to be sure it's not the signaling of the clutch, should i see 12 volts to that plug with the engine running and a/c on?

i've seen a video or two of compressor removal and it doesn't look fun. that coupled with my lack of tools / knowledge for evacuating and replacing refrigerant means i'm going to let a shop have at this project. i'm guessing a couple hundred for a rebuilt unit and a couple hours labor, $500-600?

not to mention i'm pretty sure that unit's original to the car with over 270k miles!
 

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1998 E320 base sedan @ 160kmiles
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7,215 Posts
You should see less than 1V when compressor is switched off and about battery voltage when switched on.

Have a look at the diagnosis procedure in item# 19.0 in the attached. "EC" button means EC is pressed (LED lit), and the "defroster" button depression turns on the compressor, as the defrosting function needs low humidity airflow.

STAR TekInfo

I came across a good DIY write-up that shows how to remove and install a compressor in a E430. Maybe a bit involved but doable.

W210 E430 AC Compressor Replacement Write-Up

Get a Denso compressor for about $250, and you also need a receiver/drier replacement which is not a big deal.
 

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1998 E320 wagon
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On a V6 I found compressor installation to be particularly tedious because the compressor isn’t indexed to the block. You have to hold it in just the right place to start a bolt. You either work with your arms extended or risk dropping the compressor on your face.

Why did MB update the hose between the condenser and receiver? Or can the old hose be reused despite what that excellent writeup discount parts websites say?

Sixto
98 E320 wagon 197K miles
 
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