[Pancho22]

Hi all, wondering if someone can point me in the right direction.

The radiator fan is not turning on causing the car to overheat. It does not come on when the ac is turned on and it doesnt come on even though the temp is climbing all the way to 217-219 degrees,

I shut it off after this to not let it keep climbing. I researched the overheating light is illuminated at 244... I'm checking the temp with a scanner.

I've checked fuse 28 and it's good.
I've checked the fan directly with 12v and it turns on.
Is this due to a faulty SAM?
Bad Relay?
I've checked the 3 relays behind the SAM but not entirely sure if those are busted or which one is for the fan?
Kind of thinking of wiring something directly but would rather leave it stock since it's for my gf's mom.

Any help is appreciated, thanks!

 

[toaster]

The radiator fan is driven by the SAM. It receives engine temperature data from the ECU via CAN. Since you are able to read temperature data, I'm guessing this communications link is good.

See the following for radiator fan connector and wire/pin information (connector N11-10, pin-3, Red/Blue):

451 SAM Unit Pin Out | Evilution

www.evilution.co.uk

This site IDs many (but not all) of the relays on the SAM, however there is not one labeled for the radiator fan:

SAM unit relay configuration

The home of modification and maintenance for your smart.

www.fq101.co.uk

A few additional relays are ID'd on the Roadster SAM, but again nothing for the radiator fan:

Relay Configuration

The home of modification and maintenance for your smart.

www.fq101.co.uk

Possibly the fan is driven by an IC driver, especially if it is operated at multiple speeds, ie low for engine cooling and high for A/C.

~toaster

 

[jwight]

According to this site there is a relay (K59) for the fan motor, located on or near the SAM: Fuse Box Diagram Smart Fortwo (W451; 2008-2015)

 

[Pancho22]

Appreciate the responses, I will check those things out today. I also saw on a previous post someone used contact cleaner and crc 2-26 and this worked for them. I did this yesterday but let it dry overnight. I will check today if this worked or helped at all. Along with the wiring and a relay.

 

[Pancho22]

Okay so after cleaning the connections on the SAM and relays the fan kicks on!
But I still see the temperature climbing, now I gotta track the overheating issue. I doubt the coolant temp sensor is on the fritz but I'm going to order one anyways just in case it is. That might explain why the fan wouldnt turn on sometimes? Unless there is another sensor somewhere?
I was thinking of bleeding the system in case there is air trapped in there.
Anyone have tips or tricks in case it is the water pump or t-stat?
Is it better to lower the engine or remove it all together?

She just got the car a few days ago and now this is happening.. first time working on a smart car for me.

 

[gtdump]

Okay so after cleaning the connections on the SAM and relays the fan kicks on!
But I still see the temperature climbing, now I gotta track the overheating issue. I doubt the coolant temp sensor is on the fritz but I'm going to order one anyways just in case it is. That might explain why the fan wouldnt turn on sometimes? Unless there is another sensor somewhere?
I was thinking of bleeding the system in case there is air trapped in there.
Anyone have tips or tricks in case it is the water pump or t-stat?
Is it better to lower the engine or remove it all together?

She just got the car a few days ago and now this is happening.. first time working on a smart car for me.

Have you tested the thermostat itself?
They're usually cheap, but I have been known to pull a thermostat and toss it in a pan of water to test. Put the pan on the stove and the thermostat should open before the water boils, if not it's bad. They can also be stuck open, but then the issue is not getting enough heat rather than too much.

 

[Pancho22]

Have you tested the thermostat itself?
They're usually cheap, but I have been known to pull a thermostat and toss it in a pan of water to test. Put the pan on the stove and the thermostat should open before the water boils, if not it's bad. They can also be stuck open, but then the issue is not getting enough heat rather than too much.

The thermostat is my next guess and issue. I was attempting to bleed it right now and checking it out. I get no coolant, coming from the hose right above the temp sensor on the head. My guess is bad tstat, but I'm leaning to replace both the water pump and tstat while in there. Now I just gotta see how difficult it is to drop the engine and whether, I'll do it or if I take it to a shop.

No coolant was coming out at operating temp and I shut it off before it keeps climbing.

 

[jwight]

Have you checked the oil for any signs of coolant? If there's no coolant coming out of the hose at normal temp, where did it go? 🙂

 

[Pancho22]

I have checked the oil, through the dip stick and no mixing there or in the reservoir. I have not drained the oil though. No bluish smoke from the exhaust.

 

[Pancho22]

Update: swapped out thermostat and water pump. (I believe tstat was bad as it didnt open in hot water) Put coolant and bled the system. Car was doing good while stationary. I let it sit and the fan kicked on then dropped the temp twice (2 cycles). After that I took it on a short drive and the temperature seemed to be doing great. I thought I was done....
So I was driving it to my gf's house and I have my scanner plugged in monitoring the temp and I see it starts climbing, the fan is still on but it kept going up. I pulled over and shut it off.
Could this still be air in the system or is this the radiator? It's the last thing left before the head gasket and I dont have coolant mixing with the oil, or any weird color exhaust fumes. This car is driving me nuts lol..