Uh oh, odd noise on shutdown, A/C related, 451 - Smart Car Forums
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post #1 of 38 (permalink) Old 06-24-2019, 02:18 PM Thread Starter
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Uh oh, odd noise on shutdown, A/C related, 451

This just surfaced a couple days ago and is repeatable & consistant.

When I turn the A/C off, I hear a sustained (5-10 second) noise apparently coming from the front end, which slowly winds down.
It sounds like a bad bearing. It happens whether the car is warmed up or not, whenever the A/C is turned off, even if the engine remains running.

I'm fearing an expensive and manditory repair may be in my near future.

Any other thoughts would be appreciated.

2009 smart 451 passion, 59K miles.


EDIT: I've added a recording which may be helpful. Still sounds like a bad bearing to me (but where?). I accidently recorded with AGC switched on on my recorder, which exaggerates the A/C noise. Placed inside front with service flap off.

Last edited by NCC1701; 06-24-2019 at 05:19 PM.
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post #2 of 38 (permalink) Old 06-24-2019, 02:49 PM
 
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That’s the pressure going through the expansion valve it’s normal
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post #3 of 38 (permalink) Old 06-24-2019, 03:00 PM Thread Starter
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Quote:
Originally Posted by Goofybutsane View Post
Thatís the pressure going through the expansion valve itís normal
I wish I could accept that. But, I've been driving 451's for nearly 11-years, never heard this before.
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post #4 of 38 (permalink) Old 06-24-2019, 03:51 PM
 
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If it’s a hissing noise after you kill it that’s the expansion valve. It’s on the front of the firewall that’s why it only does it when the ac is on.
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post #5 of 38 (permalink) Old 06-24-2019, 04:19 PM Thread Starter
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Quote:
Originally Posted by Goofybutsane View Post
If itís a hissing noise after you kill it thatís the expansion valve. Itís on the front of the firewall thatís why it only does it when the ac is on.
I've added a recording of the sound to Post No. 1
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post #6 of 38 (permalink) Old 06-24-2019, 05:45 PM
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I'll bet it's a bearing in the motor that runs the fan...
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post #7 of 38 (permalink) Old 06-24-2019, 06:06 PM
 
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Yeah just watched the video. Sounds like the bearings in the fan are on their way out. Dig around you may get lucky and just have a dead bird or something in there
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post #8 of 38 (permalink) Old 06-24-2019, 06:39 PM
 
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I had same noise. Exact same noise. The blower fan is my source. Easy to take out if you know how. 5 min to take off, 5 min to put back in. Took mine off dusted it off, oiled it up. My plastic fan has a crack in two places, but I put in back in. No more noise and the air blows fine. I also checked my cabin air filter I but dusty for being a year and a half old. Now due to cracked plastic fan speed 1,2,3 and 4 are fine. speed 5 the fan must expand and contacts the outer housing and that makes a noise.

Ill try the cheapest thing first..... Never use fan speed 5 ...lol.

Second, when I change the cabin air filter I will take the blower out again and glue the cracked area.

Third, get a new blower or if doable just a plastic fan replacement. So I will be on the look out for one. My buy in desire is $75.00 if I run in to one at the price i will get it.... if not speeds 1 -4 only lol.

Not a big deal fix. for your car just drive the car around with the blower off and insure the car is fine other than this blower noise.

Your Smart is not critical juts read and watch videos on how to remove the blower fan and cabin air filter.

Last edited by twcom; 06-26-2019 at 10:54 PM.
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post #9 of 38 (permalink) Old 06-24-2019, 08:24 PM
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^^^
Radiator fan, not the HVAC fan.
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post #10 of 38 (permalink) Old 06-25-2019, 06:56 AM
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If you have the service flap off and watch the radiator fan you'll probably get a better idea of where the noise is coming from.
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