Is This Noise Normal?

[Gulfstream]

A guy in the grocery store parking today has inspired this post. He was standing in the next parking spot and when I shut my truck off he asked me if my hamster had just died ?.

I've had this sound since my truck was new and always just chalked it up to just one more weird noise emanating from my 2021 F150 PowerBoost Hybrid. I have already eliminated the annoying backup beeper, but I don't think I have seen anyone else ask about this exact noise. This happens when turning the truck off, regardless whether in ICE mode or in Electric mode. This sound is the AC (fan?, compressor?, I don't know) winding down and happens every time. Is this the normal sound? You may need to turn up your volume to appreciate this quite loud, noticeably embarrassing sound. The attached recording doesn't do justice to how this sounds in person. Thanks!

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[HammaMan]

Where is the noise at? Sounds like an old brigs motor spinning down post spark cut-off.

 

[Gulfstream]

Where is the noise at? Sounds like an old brigs motor spinning down post spark cut-off.

Yes, a motor spinning down is a good description. The sound is coming from the engine compartment. I guess I need to duplicate the noise again while closely looking for the exact source. It definitely is an AC sound because even when in full power accessory mode (power-on-engine-off) when I turn the climate control off I can hear the spinning down sound. I'm just curious if other's have heard this when turning off their climate control or just shutting off the engine.

 

[HammaMan]

That's not the AC. It spins down faster than that and doesn't free wheel. I was expecting to hear the traction motor spin down with a light sprague clutch click sound.

 

[Gulfstream]

That's not the AC. It spins down faster than that and doesn't free wheel. I was expecting to hear the traction motor spin down with a light sprague clutch click sound.

Okay, thanks. I will have to try to pin this down a little more precisely tomorrow. Two thoughts regarding your comment: 1. In full power accessory mode (engine off), why would the traction motor spin-up in the first place? And 2; If that is the traction motor would that be a noise/condition that would be normal?

 

[HammaMan]

Okay, thanks. I will have to try to pin this down a little more precisely tomorrow. Two thoughts regarding your comment: 1. In full power accessory mode (engine off), why would the traction motor spin-up in the first place? And 2; If that is the traction motor would that be a noise/condition that would be normal?

The traction motor doesn't spin in accessory, nor does the AC for that matter. The fans shouldn't be on either unless there's a high temp condition which even then I'm not sure of the exact logic (though I do recall them running in acc before but haven't dug further into the variables)

In accessory the only things that should be working is the HV cooling pump for the DC-DC and that's only when it's on. The HVB will run the 12v system in accessory mode only when the HVB SOC is greater than 42%. Below that the 12v batteries are the source of accessory power. I wouldn't be surprised to hear that the the cooling pump on the HV loop still runs as ford has some poor logic in the EVs that defaults all cooling pumps on despite the vehicle not being used (ie: updates).

That noise sounds like something is out of balance. Have you looked at the cooling fans? With the vehicle in a safe condition, inspect / spin each one to make sure all is well.

 

[Gulfstream]

The traction motor doesn't spin in accessory, nor does the AC for that matter. The fans shouldn't be on either unless there's a high temp condition which even then I'm not sure of the exact logic (though I do recall them running in acc before but haven't dug further into the variables)

In accessory the only things that should be working is the HV cooling pump for the DC-DC and that's only when it's on. The HVB will run the 12v system in accessory mode only when the HVB SOC is greater than 42%. Below that the 12v batteries are the source of accessory power. I wouldn't be surprised to hear that the the cooling pump on the HV loop still runs as ford has some poor logic in the EVs that defaults all cooling pumps on despite the vehicle not being used (ie: updates).

That noise sounds like something is out of balance. Have you looked at the cooling fans? With the vehicle in a safe condition, inspect / spin each one to make sure all is well.

Great info, HammaMan. As you have suggested, I will have a much closer look at those fans. But, one confounding item is that the noise can be easily duplicated in ACC mode by just turning the climate control off. If you turn it back on and then off again, the noise will repeat.

 

[HammaMan]

Great info, HammaMan. As you have suggested, I will have a much closer look at those fans. But, one confounding item is that the noise can be easily duplicated in ACC mode by just turning the climate control off. If you turn it back on and then off again, the noise will repeat.

Check the cooling fans. The AC compressor on my MME is much louder than the one in my truck. Both are HV driven units. The MME's is so loud ford changed its logic where it only ramps up to full when the vehicle is in motion to hide just how loud it is. As the vehicle slows down, it winds down to a quieter level. Inspecting the cooling fans is easy, use a bucket or something to look down in there. Might even try turning it on w/ AC to see if it's the fans if the off check doesn't reveal anything.

 

[Gulfstream]

Check the cooling fans. The AC compressor on my MME is much louder than the one in my truck. Both are HV driven units. The MME's is so loud ford changed its logic where it only ramps up to full when the vehicle is in motion to hide just how loud it is. As the vehicle slows down, it winds down to a quieter level. Inspecting the cooling fans is easy, use a bucket or something to look down in there. Might even try turning it on w/ AC to see if it's the fans if the off check doesn't reveal anything.

I just went out and tried to pin down the exact source of the noise. Had the wife sitting in the truck pushing buttons while I hovered over the engine compartment standing on a two-step ladder. So, a slight modification of the circumstances; The noise is definitely AC related. With the engine running and the AC on, the sound can be initiated by turning the AC off. There is no noticeable sound when the AC is turned on, but, each time you turn the AC off with engine running the sound is there. Also, every time you turn the engine off, while the AC is on, the sound occurs. The sound actually does not occur (at least not today) with just the ACC on.

As far pinning down the exact location, I had no luck. It is almost impossible to see very much in there but I tried listening using a 20 inch screwdriver with the tip set on various areas of the engine compartment and the handle gingerly placed on my ear opening, sort of like a shade-tree-mechanic's stethoscope. The sound was mostly very noticeable on the top front of the engine block with no other area, including the fan, producing anything suspicious as far as I could tell.

Now I'm wondering if it could be the compressor?

 

[Ford Motor Company]

A guy in the grocery store parking today has inspired this post. He was standing in the next parking spot and when I shut my truck off he asked me if my hamster had just died ?.

I've had this sound since my truck was new and always just chalked it up to just one more weird noise emanating from my 2021 F150 PowerBoost Hybrid. I have already eliminated the annoying backup beeper, but I don't think I have seen anyone else ask about this exact noise. This happens when turning the truck off, regardless whether in ICE mode or in Electric mode. This sound is the AC (fan?, compressor?, I don't know) winding down and happens every time. Is this the normal sound? You may need to turn up your volume to appreciate this quite loud, noticeably embarrassing sound. The attached recording doesn't do justice to how this sounds in person. Thanks!

Hi there, I'd be happy to look into your F-150 concerns on my end. Will you send us a message with your VIN and dealership info? I can look into things on my end.

 

[HammaMan]

I just went out and tried to pin down the exact source of the noise. Had the wife sitting in the truck pushing buttons while I hovered over the engine compartment standing on a two-step ladder. So, a slight modification of the circumstances; The noise is definitely AC related. With the engine running and the AC on, the sound can be initiated by turning the AC off. There is no noticeable sound when the AC is turned on, but, each time you turn the AC off with engine running the sound is there. Also, every time you turn the engine off, while the AC is on, the sound occurs. The sound actually does not occur (at least not today) with just the ACC on.

As far pinning down the exact location, I had no luck. It is almost impossible to see very much in there but I tried listening using a 20 inch screwdriver with the tip set on various areas of the engine compartment and the handle gingerly placed on my ear opening, sort of like a shade-tree-mechanic's stethoscope. The sound was mostly very noticeable on the top front of the engine block with no other area, including the fan, producing anything suspicious as far as I could tell.

Now I'm wondering if it could be the compressor?

It could be, the vin bot results leave much to be desired. Did you inspect the fans with the key off? Could be a bad AC -- anything unusual with its function?

 

[Los150]

To me, it sounds like a fan blade slightly clipping something. I had a PC that ran fine once but when I shut it off, the fan would shift slightly on the shaft as the air pressure dropped. It was moving slightly toward the front grille and clipping it.

It's reminding me of that situation.

 

[Gulfstream]

It could be, the vin bot results leave much to be desired. Did you inspect the fans with the key off? Could be a bad AC -- anything unusual with its function?

Thanks, Hamma, for the effort. I guess it's time to schedule a trip to the dealer.

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