[degibbo]

G'day,
2008 Smart ForTwo (1l Turbo - Australian).
The AC button responds (toggles the LED indicator on or off) but has no other effect.
The compressor cycles on and off as normal and it cools nicely. So, a few questions:

Does anyone know how the AC is actually powered?
Is there an AC relay (with stuck contacts) somewhere?
If so, where is it actually located?

Any advice would be appreciated, as would access to a wiring diagram!

Cheers & thanks,
Degibbo

 

[stevenjb]

Try turning the fan to off, if this turns the compressor off then it could be a bad switch.

 

[degibbo]

Thanks for responding to my query. Yes, the compressor requires the fan to be on, just as per normal operation (Fan off = Compressor off).
I am not sure which switch you are referring to. The AC button on the dash is a momentary switch that correctly reports to the SAM that the button has been pressed. The apparent "state" is reflected by the button LED illumination. The state is also remembered by the SAM. If I press the AC button for AC on, & the LED illuminates, then when I turn the car off, and press the AC switch again, when the car starts next time the AC LED is still on, thus eliminating any problem with the AC switch. The SAM doesn't know that there is any issue.

Somewhere there has to be a relay to enable / disable the AC power for the compressor when the Fan is on. This may be inside the SAM or external somewhere.

Cheers & thanks for your interest,
Degibbo

 

[Rustedwrench]

I am not completely clear on your issue. If the a/c is on when the ignition is switched off the a/c will still be on when the car is restarted. If you want the a/c off then turn it off before you turn the car off, then it should be off when the car is restarted.

 

[degibbo]

G'day Rustedwrench,
You are right of course, but in my case the AC is ALWAYS on regardless
of the AC state indicator LED on the AC switch, which toggles on and off
with every second press of the AC switch. The AC cannot be turned off
by pressing the AC switch - ever, but the LED turns on and off as normal
and follows the function rules that you described.

Any suggestions as to where the problem might be?

Cheers & thanks,
DG

 

[Rustedwrench]

The a/c switch on the hvac control unit results in a networked signal for a/c request sent to the SAM (fuse/relay panel) by way of the CAN network. The SAM has a internal relay that sends power to the a/c compressor.

 

[degibbo]

G'day Rusted wrench,
Now we are getting there. I have had a look (at evolution) at the internals of the SAM, but there was no relay identified as being for the AC. I will investigate though, now that I know where the relay is. It is now just a question of which one, but with suspected frozen contacts, it should be easy to identify.

Thanks for your help,
Degibbo