A/C Compressor Noise

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A/C Compressor Noise

Postby Mark IV VIenna » Sun May 02, 2021 11:24 am

Hi everyone,

Recently, my A/C Compressor (1973 Mark IV) started making this terrible noise. I figured this is because there was no pressure left in the system. So I pressurized it (with regfrigerant from cans), but the noise didn`t change. Is there anything I might try other than dismantling/replacing the compressor? There should be a video with sound here: https://www.dropbox.com/s/t3xu0ctmq62lo ... 2.mp4?dl=0

The system seems to be without leaks and is producing cool air.

(Background: My ATC used to be stuck on max heat. Eventually I found the issue. That was an interesting story - and a septerate thread. Heater output / vent could be controlled ever since, however A/C was depressurized and out of order. I didn`t care as it was wintertime. And I figured the compressor wouldn`t run anyway as ATC was in heating or vent mode most of the time and as compressors usually have a low pressure cutout switch. Then, a couple of days ago the noise started.)
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Re: A/C Compressor Noise

Postby action » Sun May 02, 2021 3:45 pm

Likely the compressor is failing.
If the system leaks, some oil can come out with a leak. Over time the oil loss can be too great.
Because just adding refrigerant does not put any oil back in the system

Not sure what type of compressor you have. A6???
If bearings are failing, the longer you wait the more metal is spread throughout the system. Getting any debris including metal out of the system after a repair is key to not having a come back repair.
Replacing the receiver/dryer and maybe flushing the system may be needed as well.

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Re: A/C Compressor Noise

Postby Mark IV VIenna » Mon May 03, 2021 2:46 am

Well, like I said, the whole system had zero pressure left in it. And it had been sitting like this for years. As a home mechanic with no prior experience in A/C I just wanted to see whether this could be an easy fix. Thus the regfirgerant cans. I know this is a long shot, but we are in lockdown over here which gives us time to occupy ourselves with things we didn´t care about before. :grin:

Interestingly, I do not have traces of any oil leaks somewhere on the A/C. Also, the noise was there all of a sudden. It was fine before. I know the compressor is probably doomed - I am just looking for advice on things I might have missed that can be checked before dismantling everything. Like - could it be just the clutch?

It is an A6 (OEM) compressor, the belt is new, tension is fine. Also, the compressor can be turned smoothly by hand with reasonable effort.
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Re: A/C Compressor Noise

Postby action » Mon May 03, 2021 2:34 pm

OK now I am confused.

In one post you stated, "Recently, my A/C Compressor (1973 Mark IV) started making this terrible noise."
then you stated, "the whole system had zero pressure left in it. And it had been sitting like this for years"

Even though I have a '66 with ATC I have disconnected the clutch because I do not want the compressor to come on until I go through it. And I am not sure how it is set up. Because some earlier systems did NOT have a low pressure switch to control the clutch. You may or may not, I just don't know.

If the system has had zero pressure for years, it was due to a leak.
Leaks may or may not leave traces of oil.

Diagnose the issue -
If you are not sure of the source of the sound - clutch or compressor
And you have a pound or two of refrigerant in the system, turn it on.
Use a stethoscope or a couple foot section of hose. (Old garden or heater hose will work)
Determine if the sound is from the from the body of the compressor or from the clutch.

Repair/or replace as needed.
And first you might want to find the source of the leak. It may be the leak is in the compressor.
Or it could be a line or fitting.

The A6 compressor is rebuildable. However based on this statement, "As a home mechanic with no prior experience in A/C"
I would recommend replacement if the compressor is bad. And A6 can be had on Ebay with clutch for $250 to $300.
I would also recommend getting a gauge set if you do not have one.
If you don't have one and will not get one, hire out the job.

The other thing I would recommended if the compressor is being replaced is flushing the system. Cleaning out any debris is important. The compressor may be coming apart. The pieces that come apart will get distributed in the system. Removing those pieces is very important.
Replacing the receiver dryer would be required as one of the functions is catching debris. Maybe replace the expansion valve or at least inspect if debris is found during flushing.

This is the time of year for AC repairs. Without the correct diagnosis, tools and instructions or experience, the job can get to be a mess.
It is possible for an inexperienced person to take this on. All techs had zero experience at one point. Doing this without a shop manual, gauge set and a vacuum pump is not recommended. More harm than good can come of AC repairs started without the correct tools.

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Re: A/C Compressor Noise

Postby Mark IV VIenna » Tue May 04, 2021 3:57 am

Sorry about the confusion I caused! It is a long story :grin:
Before I bought it, the car had been sitting for several years, ATC worked on max heat only, and the (low gauge) pressure on the A/C was zero. However, when pushing on the valves, some pressure could still be observed. So I thought the system might just be clean of contamination, thought the loss of pressure over all those years might be normal and some canned sealant and canned refrigerant could just bring the system back alive. That was last September, and I planned to follow that thought in springtime = now. Unfortunately, a few days before I got around to fill the system the compressor started making this noise.
Why did I take half a year (wintertime) in between solving the max-heat-only problem and this attempt? And why didn`t I unplug the clutch? Because I thought that a) the compressor wouldn`t engage while the system is in heating operation and b) that there was a min. pressure cutout switch. The shop manual proves me wrong twice… STUPID, STUPID, STUPID mistake!!!

Anyway, it might just be the clutch, as the noise originates from that area. Also, it gets hot. So before I have a proper system overhaul done by a professional I am still looking for a hunch whether the clutch can be swapped without removing the compressor from the car. After all, if the clutch is the problem, it probably won`t have distributed debris in the system. Also, on the third day after refill, the system is still at 70psi (hi and lo, engine not running) as the manual suggests. So it might be without leaks.
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Re: A/C Compressor Noise

Postby action » Tue May 04, 2021 7:10 am

I am less familiar with the A6 than other compressors.

But I would bet the clutch can be replaced without opening the system and on the car, This is true for many other compressors.
Most of the A6 compressors are located rater high up in the engine compartment. Making access easier.

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Phoenix - Yeah, it's hot, however it's a dry heat
2006 Lincoln Navigator Limited 5.4l 3V
1996 Lincoln Mark VIII 2DR Coupe Diamond Anniversary 4.6l DOHC, 4R70W, 3.07
1970 Continental Mark III Triple Black 460 4v, C6, 2.80 (Used for Woodward Dream Cruise or just generally stored in Michigan)
1966 Lincoln Continental 4DR Convertible 462 4v, C6, 3.00
1966 Mercury Park Lane 4DR Breezeway 410 4v, C6, 2.80
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Re: A/C Compressor Noise

Postby action » Tue May 04, 2021 7:30 am

I thought I could find a vid. No such luck.

Did find this -
https://www.shopcenturyautoair.com/stor ... _7634.html
You may need snap ring pliers as well.

This may help
https://www.youtube.com/watch?v=fe_y7kgM4Rk

And the shop manual will be your friend.

Action
Phoenix - Yeah, it's hot, however it's a dry heat
2006 Lincoln Navigator Limited 5.4l 3V
1996 Lincoln Mark VIII 2DR Coupe Diamond Anniversary 4.6l DOHC, 4R70W, 3.07
1970 Continental Mark III Triple Black 460 4v, C6, 2.80 (Used for Woodward Dream Cruise or just generally stored in Michigan)
1966 Lincoln Continental 4DR Convertible 462 4v, C6, 3.00
1966 Mercury Park Lane 4DR Breezeway 410 4v, C6, 2.80
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Re: A/C Compressor Noise

Postby tomo » Tue May 04, 2021 11:04 am

Are you sure that there is no low pressure switch? I had air-conditioning on cars from the late 1950's all of the way up to 2013 and starting with a 1958 Mercury all of them had low pressure switches to deactivate the clutch circuit.

I saw your video and it sounded like your compressor was toast. This would be a good time to convert your system to R1234yf. The 1973 AC used R-12 and if you tried to fill it with R134A, which is what is easily available at most store, it would destroy the bearings in the compressor. If you system was converted to R134, there should be a tag or sticker indicating this.
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Re: A/C Compressor Noise

Postby action » Tue May 04, 2021 11:56 am

tomo wrote:Are you sure that there is no low pressure switch?


I am not sure of anything on the post York/Tecumseh AC systems.
I have never had a vehicle that had an A6 compressor. (However at one time I guy gave me a crate of 4 Ag compressors to have. I sold them)
I am more experienced with orifice tube systems

If there is a low pressure switch, I have not seen one. Doesn't mean there isn't one.

Action
Phoenix - Yeah, it's hot, however it's a dry heat
2006 Lincoln Navigator Limited 5.4l 3V
1996 Lincoln Mark VIII 2DR Coupe Diamond Anniversary 4.6l DOHC, 4R70W, 3.07
1970 Continental Mark III Triple Black 460 4v, C6, 2.80 (Used for Woodward Dream Cruise or just generally stored in Michigan)
1966 Lincoln Continental 4DR Convertible 462 4v, C6, 3.00
1966 Mercury Park Lane 4DR Breezeway 410 4v, C6, 2.80
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Re: A/C Compressor Noise

Postby TonyC » Tue May 04, 2021 11:57 am

Yes, there has to be a cutoff switch for the clutch; without it, the system would freeze up, literally, from the inside. That switch on old Fords would be placed on top of the evaporator case and have a thin capillary tube running into the center of the evaporator core. That tube senses icing; when the evaporator starts to freeze up, the tube engages the switch and kills power to the clutch, stopping the freon flow and thawing out the system.

But the switch would not operate until it sensed freezing up; I suspect that all that freezing would do a number on an evaporator core and maybe other close parts, which may be one of the reasons they developed a timed switch in the mid-'70s to operate the clutch. Instead of waiting for an icing-over to occur, the timer would cycle the clutch on and off at a preset interval, probably to protect the parts from freeze damage. It also had a minor benefit to fuel economy, which was a big thing by then: If something saved even one milliliter of petrol in a mile's travel (I know, mixing metrics with American again!!), it was heralded as a world-saver.

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Re: A/C Compressor Noise

Postby action » Tue May 04, 2021 12:01 pm

TonyC wrote:Yes, there has to be a cutoff switch for the clutch; without it, the system would freeze up, literally, from the inside. That switch on old Fords would be placed on top of the evaporator case and have a thin capillary tube running into the center of the evaporator core. That tube senses icing; when the evaporator starts to freeze up, the tube engages the switch and kills power to the clutch, stopping the freon flow and thawing out the system.

---Tony


Wrong switch Tony!

That is for evaporator temp control.

The switch in question would be a low system pressure switch. That would sense the system is low on refrigerant and stop the clutch from engaging. This would be a measure to protect the compressor from running when there is little to no refrigerant.

Action
Phoenix - Yeah, it's hot, however it's a dry heat
2006 Lincoln Navigator Limited 5.4l 3V
1996 Lincoln Mark VIII 2DR Coupe Diamond Anniversary 4.6l DOHC, 4R70W, 3.07
1970 Continental Mark III Triple Black 460 4v, C6, 2.80 (Used for Woodward Dream Cruise or just generally stored in Michigan)
1966 Lincoln Continental 4DR Convertible 462 4v, C6, 3.00
1966 Mercury Park Lane 4DR Breezeway 410 4v, C6, 2.80
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Re: A/C Compressor Noise

Postby Mark IV VIenna » Wed May 05, 2021 2:27 am

First of all, I like the idea of saving fuel by cycling an A/C clutch - on a 460 CUI V8 :D
Anyhow, the 1973 Mark IV uses a suction throtling valve system to keep the evaporator from icing. I learned that from the shop manual. Also, there is an ambient temp cutoff switch somewhere on the front of the car that deactivates the compressor below 4 degrees celsius. But no low pressure cutout switch - the manual doesn t mention one either.

I used R600/R290 mixture, which is supposed to be compatible with R12 systems. However, I do not know what the previous owners of the vehicle used...

I will watch system pressure for a couple of more days. If it stays at its current reading I will take a shot at replacing the clutch, if the system leaks anyway I will probably go for a new compressor (and expansion valve and receiver). Or live without A/C.

The fun part is that although the noise comes from the clutch area I cannot explain what could be wrong there. The noise is only there when A/C is engaged. So it cant be the pulley bearing, as this is spinning all the time, A/C on or not. And the cltuch drive plate and driven plate are pressed together once the clutch engages, moving as one. I don t see what could cause friction and noise here!
Last edited by Mark IV VIenna on Wed May 05, 2021 4:38 am, edited 1 time in total.
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Re: A/C Compressor Noise

Postby TonyC » Wed May 05, 2021 2:42 am

action wrote:Wrong switch Tony!

That is for evaporator temp control.

The switch in question would be a low system pressure switch. That would sense the system is low on refrigerant and stop the clutch from engaging. This would be a measure to protect the compressor from running when there is little to no refrigerant.

Action


Okay, if you say so. Maybe that is some new safety doohickey they came up with in the '70s for newer systems (which is what applies to the OP's case here). There was no such switch in the '60s systems; the icing-control switch on the evaporator was the only cutoff switch in the entire system. But, I admit, my best experience with A/C systems has been with the '60s designs; I've been out of touch with later systems for about a generation now.

---Tony
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Re: A/C Compressor Noise

Postby action » Wed May 05, 2021 8:13 am

There will be two bearings in the front. One for the compressor and one for the clutch.
However the compressor bearing does not have to support much based on the design of the compressor.

It may be possible that either bearing only makes sounds under load of the compressor.
And removal of the front compressor bearing may be possible without blowing the charge. However access would be difficult at best
And yes removal of clutch without blowing charge can happen.
All based on this good vid
A good set of snap ring pliers and a special tool might be needed for compressor dissassembly

https://www.youtube.com/watch?v=0c7QXLNqgBU

Action
Phoenix - Yeah, it's hot, however it's a dry heat
2006 Lincoln Navigator Limited 5.4l 3V
1996 Lincoln Mark VIII 2DR Coupe Diamond Anniversary 4.6l DOHC, 4R70W, 3.07
1970 Continental Mark III Triple Black 460 4v, C6, 2.80 (Used for Woodward Dream Cruise or just generally stored in Michigan)
1966 Lincoln Continental 4DR Convertible 462 4v, C6, 3.00
1966 Mercury Park Lane 4DR Breezeway 410 4v, C6, 2.80
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