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Does anything sound off when the A/C goes on?

rolfe.oliver

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2017 GT350. Just shy of 26,000 miles. Been noticing this intermittent sound coming from the engine bay and I think its primarily tied to when the A/C is on. Anything sound off? I have a third-party warranty, so we'll see what the deal is if anything is wrong.



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If your AC works, I wouldn't worry about. Pumps whirr and make noises, that's normal.
 

sk47

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Hello; Two of the things that make noise are the compressor and the electromagnetic clutch that engages the compressor.
The video sounds like a possible compressor noise. Some depends on how the compressor operates. On an older Ford van I owned, the compressor was a piston sort and mads a distinct sound. Some are rotary type pumps which make a different sound.

The AC clutch is essentially an electromagnet mounted (EM)around a bearing assembly. You set the temp to some level and when that temp is reached the electromagnet is switched off to stop the compressor from being driven. The interior warms up and the electromagnet is energized which slams the plates together so the compressor will turn. When the AC is turned off the clutch assembly allows the AC drive belt to spin the disengaged pulley to freely rotate on a bearing.
There are also a couple of other pressure switches which can be involved. Add too much AC freon and the system gets over pressurized, so the AC EM clutch keeps cycling on and off. The AC clutch is a quick sound and not what you recorded.

There can be a sound if the bearing in the clutch assembly is failing. Had a bearing go bad on a 91 SE-R. I was lucky in that the AC compressor had it's own separate belt. Cut that belt and still had the water pump, alternator and PS working. It was a pain to get at but I bought a puller tool set and managed to replace the bearing/clutch assembly without having to remove the compressor. Did not lose the freon charge. That puller tool set has been only used that one time so far in over 20 years. The sound you have is likely not a bad bearing. When the bearing is going bad you hear a sound when the AC is off. The sound goes away when the ac compressor is engaged.
 
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rolfe.oliver

rolfe.oliver

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Hello; Two of the things that make noise are the compressor and the electromagnetic clutch that engages the compressor.
The video sounds like a possible compressor noise. Some depends on how the compressor operates. On an older Ford van I owned, the compressor was a piston sort and mads a distinct sound. Some are rotary type pumps which make a different sound.

The AC clutch is essentially an electromagnet mounted (EM)around a bearing assembly. You set the temp to some level and when that temp is reached the electromagnet is switched off to stop the compressor from being driven. The interior warms up and the electromagnet is energized which slams the plates together so the compressor will turn. When the AC is turned off the clutch assembly allows the AC drive belt to spin the disengaged pulley to freely rotate on a bearing.
There are also a couple of other pressure switches which can be involved. Add too much AC freon and the system gets over pressurized, so the AC EM clutch keeps cycling on and off. The AC clutch is a quick sound and not what you recorded.

There can be a sound if the bearing in the clutch assembly is failing. Had a bearing go bad on a 91 SE-R. I was lucky in that the AC compressor had it's own separate belt. Cut that belt and still had the water pump, alternator and PS working. It was a pain to get at but I bought a puller tool set and managed to replace the bearing/clutch assembly without having to remove the compressor. Did not lose the freon charge. That puller tool set has been only used that one time so far in over 20 years. The sound you have is likely not a bad bearing. When the bearing is going bad you hear a sound when the AC is off. The sound goes away when the ac compressor is engaged.
Thank you for the in-depth response. Does the sound make you think that it is normal operation or potentially an issue with the compressor? I know compressors are a "common" issue on GT350s, but I don't want to take it to a dealership unless there is a potential issue.
 

sk47

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Thank you for the in-depth response. Does the sound make you think that it is normal operation or potentially an issue with the compressor? I know compressors are a "common" issue on GT350s, but I don't want to take it to a dealership unless there is a potential issue.
Hello; Something to consider. Is the noise new and different or is it something that may have been going on all along and you just now noticed it? I recall the first time i changed the oil in my new truck. After putting everything back in and oil in I started it and crawled under o check for leaks. Heard a noise while running. Been near 18 years and all is fine.
If it is a new noise or louder than before then some better chance of an issue. Did not sound too unreasonable from the clip you have. That said I am not familiar with the normal AC noise of a GT350. Maybe a GT350 owner can chime in.
Thing about it is if an issue is already started running the AC more will not make much difference. It is a closed system and any wear parts are already circulating. The likely is a small filter built in which helps catch stuff, but that will need to be replaced anyway.
The question is about the third party warranty terms and time frame. If you have lots of months and time left run it the way it is.

NOTE- I am not up on newer AC units which may be some different. My actual hands on experience is dated. Especially AC units which run using an electric motor and not a belt such as in an EV.
 

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to the OP, i heard sounds in my car that were similar to your first video. the sounds eventually got worse and had to have the compressor replaced in July 2022. (Metal shaving in the compressor). and now today: my car is back at the dealer for them to diagnose a non-working A/C because the compressor doesn't turn on so it's not blowing cold air. i don't know if it's the compressor, low on refrigerant or something else. fortunately i have the extended Ford warranty and was told that the issue will be fixed at no cost to me. 😐 good thing for me is that the A/C hasn't been needed recently....
 
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rolfe.oliver

rolfe.oliver

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to the OP, i heard sounds in my car that were similar to your first video. the sounds eventually got worse and had to have the compressor replaced in July 2022. (Metal shaving in the compressor). and now today: my car is back at the dealer for them to diagnose a non-working A/C because the compressor doesn't turn on so it's not blowing cold air. i don't know if it's the compressor, low on refrigerant or something else. fortunately i have the extended Ford warranty and was told that the issue will be fixed at no cost to me. 😐 good thing for me is that the A/C hasn't been needed recently....
I'm sorry to hear your fate. Thank you for chiming in. I'm getting a wheel repaired next week, so I think I will reach out to warranty company for guidance on whether diagnostic is covered and will probably take it in to get looked at. I am weary of A/C removals/replacements since it seems bad service departments can really screw things up.
 

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NOTE- I am not up on newer AC units which may be some different. My actual hands on experience is dated. Especially AC units which run using an electric motor and not a belt such as in an EV.
You're about 98% right I'd say lol, compressors haven't really changed much aside from newer variable displacement units (piston/swash plate stroke is adjusted) and what seems like Asian specific variable displacement units that run 24/7 (no clutch).

As for OP - yeah definitely compressor. You can hear the typical squeaky pump-type of whine when the compressor is running. Probably a bad shaft bearing, swash plate piston bearing, or piston from the ones I've torn down. I've probably replaced a lot more GT350 compressors than other Mustang compressors - for whatever reason it's very common. I haven't had one grenade itself yet though unlike other Mustangs...I guess Shelby owners pay more attention to their cars? lol
 

sk47

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You're about 98% right I'd say lol, compressors haven't really changed much aside from newer variable displacement units (piston/swash plate stroke is adjusted) and what seems like Asian specific variable displacement units that run 24/7 (no clutch).

As for OP - yeah definitely compressor. You can hear the typical squeaky pump-type of whine when the compressor is running. Probably a bad shaft bearing, swash plate piston bearing, or piston from the ones I've torn down. I've probably replaced a lot more GT350 compressors than other Mustang compressors - for whatever reason it's very common. I haven't had one grenade itself yet though unlike other Mustangs...I guess Shelby owners pay more attention to their cars? lol
Hello; Thanks for the new information. No clutch in some newer units. Reminds me of a ride i had with an old high buddy not long ago. It was cold. We were in his car. I asked why he had the heat turned off. He was used to waiting for the engine core to warm up before opening a valve on the heater hose line.
I told him how the newer cars did not have a shutoff valve any more. That the coolant runs thru the heater all the time. That we have doors that open and close to direct where the air goes.

I still have an old vacuum pump and some r12 fittings. I bought an R134 manifold gauge setup but have hardly used it.
 
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rolfe.oliver

rolfe.oliver

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The car is finally in service. The advisor and porter both heard the sound before taking the car away. Hopefully the third-party warranty covers it if there is an issue.
 
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rolfe.oliver

rolfe.oliver

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Service advisor called this morning and said compressor is bad. They are ordering a new one and and replacing the old belt. Extended warranty did cover replacement.
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