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· He's not mine
9,655 Posts
Discussion Starter · #1 · (Edited)
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.

· Premium Member
1,576 Posts
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

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.

· Premium Member
1,576 Posts
Ok so I found the blower motor for my target price of 75.00 new, but taking my own advise I am riding the car to see if all else is OK.
The blower works fine with no noise but for the ,4th speed I believe due to a cracked fan. The radiator fan kicks on at 213 degrees and that spins without noise and it shuts off as temp lowers to 200 degrees and winds down with no noise as temp goes back to 186 to 188 degrees. It is only when I push the AC button the noise starts. The AC blows ice cold but the noise is heard and stops when the AC is shut off.

So its time to dig in there and repair this.

What I actually should do.

Radiator support. (broken since purchased as there was front end damage)
New condenser. (Lower tube was bent as part of the front end damage No leaks)
New Fan (source of noise)
New headlights (cracked Housings from Front end Damage)
New struts (I'm already Torn down)
New brake pads. (why not at this point)

Do all those things while I am that far into the front end any way.

On the fantasy level

Radiator support will be Stock.
Condenser will be Stock.
Fan would be dual aftermarket.
Headlights will be Brabus.
Struts will be dual adjustable.
Brake pads will be ceramic. Vented Rotors

All right now, how do I get what I need done with a touch of the fantasy all on a poor mans budget. Lol

· Premium Member
1,576 Posts
NCC1701 .......... After driving My smart to confirm noise I have decided to consider mine Very Serious and intend to put it out of service next week.

What I found is that my Condenser Fan is turning on and off at its triggered temp points. most of the time when its is active it is spinning at low speeds with no noise. There are times where it is triggered to spin at a higher speed and I can hear some slight noise. Since the AC triggers the fan to spin at much higher speed that is when the most noise is heard. So I need to repair or replace my radiator fan.

I have no doubt I can take it apart and make the physical repair or replacement But the coolant drain and recharge is beyond my capabilities. So I am going to leave it to the professionals. I'll get a Quote from the dealer so I can feel better about what the inde shop will charge. lol

The Electric fan on the front is an option I could do Myself, I'll ask some questions regarding that in the next post.

· Premium Member
1,576 Posts
Yup!! It is either the front cooling fan motor, or a broken mounting bracket. To repair it, the whole front end will most likely need to come apart. A second cheaper option is to install a pusher fan in front of the radiator and wire it in place of the stock fan. I did this a few years ago and it was much easier. The front clip needs to come off, but we are talking about maybe a dozen screws and it lifts off in one piece.
If I use the same fan as you did,

My question is could I get the old fan off and discard it with out tangling with the coolant lines? My thought is if I go with the inde shop I would prefer to remove the Original broken fan and go with a front mounted pusher fan in any case.

And this is the the only rewiring that has to be done? ..... Looking for your input.

If I want the new condenser the inde route for sure, If I wait on the condenser (mine is not leaking just visual damage) I could get this done this weekend.

· Premium Member
11,314 Posts
I left the old fan in place with no problems.The bracket that attaches it to the front radiator support is bolted from the back and you have to pull the support to get to it. Leaving it in place won't hurt anything or slow down the air flow.

Only 2 wires you need to mess with are the 2 that go to the fan. Use the wires going to the old fan and attach them to the new one. Just be sure the fan is turning the correct direction before making the connections permanent.

· Premium Member
1,576 Posts
I think it's a bad radiator fan bearing. That's the only moving item in the front end. AC compressor and water pump is all in the rear
That is a comfort. Although I intend to have rear belly pan removed and take a look to see what's lurking under there.
As these seem to be some of the least lubed cars I am sure there is a need for something to be lubed under there and might benefit from a full rust prof coating. Also a chance to check for leaks.
I do not intend to put the front belly pan back on as it hinders my access to the chassis points I periodically spray lube. I had removed the small piece of this front belly pan that was left when I got the car. 2 years I feel no I'll effect as my car is set up.

So this weekend I will make my attempt to see if I can do something small to remedy this fan condition after that, early next week inde shop Bay Diagnostics will be where I initially take the car for evaluation.

· Super Moderator
18,079 Posts
I'll also say NCC's problem is the radiator fan. Could be something stuck in there or more likely the bearings are gone or the fan itself is cracked/broken.

· Administrator
29,959 Posts

· Premium Member
1,576 Posts
So there that will not be a whole lot of misunderstanding and wasted time here is what the shop "Bay Diagnostics of Brooklyn NY" is tasked with.
We will see how it goes.

2014 Smart Fortwo passion Coupe.

Purchased in 2017 with front end damage.
Pieced back together.
Axle changed under warranty, Brake light Switched replaced,
Driven two years with out any other issues.

Primary reason for service.
Radiator fan noise

Expected repair.
Replace electric fan.

Opportunity Repairs.
Radiator bent....... Replace radiator with coolant drain and recharge.
Radiator support damaged....... Replace radiator support.

Evaluation items.
Front Struts
Front Brake Pads
Rear belly pan remove Inspect for leaks, debris, rust build up.
Transmission/gear fluid evaluate for change.
Bosch Navigation system Update.
Spare Key

Notable Items.
No front belly pan..... I do not wish to put a front belly pan back on.
Heater Blower noise at speed #4 due to cracked Hamster wheel fan .... already have new blower will swap in later.
Scratch on right side across Tridion ..... uck!
Missing hood latch covers ...... intended future signal light/reflector area.
Cracked head Light housings ....... intention is to replace with Brabus type head light after radiator support replacement.
Cracked left rear tail light....... A "One Lap Of America tour" battle scar. No intention to ever replace.

For You at SCOA to know, My Mind would not put on the factory fan, but instead sandwich the radiator/condenser with two of the O'Reilly Auto part type. One in front pushing air, one in back pulling air. I believe ( in my mind) that that would be best with fewer crackable and failure prone parts to deal with. with the hard pothole shots the Smart is subject to, any plastic composite parts that are part of structure are subject to crack failures and as I intend many more hard cross country runs this Factory Fan must be expected to fail again. Now I fully believe this car was engineered very well, minus the lack of lubrication for anything moving, rotating or pivoting lol. I will be putting the Factory fan back on. Still I may have an O'Reilly type installed on front anyhow. This car is scheduled to run NYC to Seattle WA., then down the Pacific Coast Highway to LA, Plan is to then attempt route 66 patterned run to Chicago on the way back to NYC. So the cooling system I am repairing now will be what has to endure all that that trip will require next May. Yeah. The secondary fan is in lol.

So we will see how much I can get done on this, the front, Less expensive, end of the car. The rear high Dollar end of the cars spruce up, should come during the fall and winter months.

May the sticker shock of repair estimates be kind to me.
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