Hello all,

I have a 1983 300D, and I've just developed a loud squeaking noise when the AC is on. It goes away as soon as I hit the Economy button, so I think it's the compressor itself, and not the blower. The PO included some service records showing that the compressor was replaced in May of 2019, so I'm wondering if there's some bearing somewhere that needs replaced after ~37 years. The AC still blows cold, but I don't want to break anything, and I don't want to listen to the squeak haha

I looked at the manual to replace an electromagnetic clutch in the AC system, but I don't know if that's right. https://www.tonk.ca/models/w123/w123CD2/Program/Climate/83-256.pdf

Anybody have any wisdom they could lend me for this?

Checking the compressor belt tension might be a good place to start. That, along with nailing down the exact location of the offending noise.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

I recall hearing that the GM R4 compressors have a seal or something installed in one direction and when installed on a Mercedes engine it is upside down to the standard GM orientation and it can wear out a seal or bearing or something.

I'm probably way off with that memory, but perhaps someone can chime in and correct me.

I had AC on one of my cars begin making a slight squeal, I replaced the belt and it seemed better, I took the car on a 4 mile drive and halfway through there was a massive amount of squealing, followed by a tremendous amount of smoke from under the hood and then a KACHUNK FWAP FWAP HRBDLEDYBRRRF sound, I stopped just in time to see the belt fly from under the car, the compressor had completely seized up.

I'd do as tangofox suggested and determine exactly what component is causing the squealing, is it the belt or is it a bearing?

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1982 300D (w123, "Grey Car")
1982 300D (w123, "Blue Car")
2001 Ford F150 "Clifford" (The Big Red Truck)
1997 Dodge Ram 2500 12V Cummins
1996 Dodge Ram 2500 12V Cummins
Previous Vehicles:
1995 E300D, 1980 300SD, 1992 Buick Century, 2005 Saturn Ion

I would check, as previously stated, the belt for looseness - which can cause squealing. If it's too tight, it could cause the adjuster pulley to squeal as well as wear down the pulley's bearing.

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Don't Chrome them; polish them

My 82 w123 did not have an adjuster pulley on theA/C. It was the compressor that got adjusted using the 10 mm hex nut.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K

If the PO replaced the compressor in 2019, I doubt the sound is coming from there.

I think checking for loose or worn (sinking into the pulley groove) v-belts would be where I'd start.

I replaced the belts about a year ago, so they're all new, and the tension feels good to me. I will double check it, though, because I did have to retighten the bolt for the alternator tension.

Unfortunately(?), I won't be able to tell if that caused the noise, because it went away yesterday after I drove over a fairly bad washboard road. I don't see how this could have fixed anything, though, so I fully expect the noise to return.

Thanks for your help!

That would depend what the compressor was replaced with. Not all replacement parts are new.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

That's true tango- the total for the compressor was only $130 per the invoice I have. It probably was used.

I had your exact same symptoms on my '81 300SD and diagnosed it as a squeaking water pump. So I replaced the water pump, fired it up and had the same exact noise.

Yep, it was the AC compressor all along.

Ah, true.

IIRC these 617's have the AC Delco compressor? I think if air gap is off with the clutch in those, it can cause squeaking.

Yes, the compressor used was a GM R4. Also note that the R4 was not really meant for r134a. It has higher head pressures. When I had my w123, I replaced the compressor with one of the last Hancock Ind made, new not rebuilt compressor. I had to replace the bearing, as the 134a would stall the compressor when the engine was idling, and make the clutch smoke.

The bearing was replaceable without fully removing the compressor from the car.

I then switched to Duracool. That stuff made a huge difference. Lower pressure and as efficient as R12.

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RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K