406 Stop light and warning tone - A/C?

Thanks, Mike, I'll have a look at this - someone had suggested a relay in the box behind the front grill being faulty or corroded - we did take it out along with the other two relays in the box, and although they were slightly corroded (we cleaned them up), they all tested out as working ok, so that never got us anywhere - will definitely have a look at your idea though.

Failing that, does anyone know where I can get wiring diagram for a

406?

I can email you one, but do the fans come on slow speed when the A/C is switched on. If not, and they should, then there is a fault with the relays or the resistors or even the wiring. All available seperately.

I'm slightly farther on with this problem - the fan is only coming on when the high pressure side reaches around 16 bar, and then only for a few seconds, enough to bring it down to around 10 bar, then the cycle continues. I don't know if the problem is one, two, or all of the three relays inside the plastic box, or the resistors that sit up beside the fan - anyone any ideas? I'm assuming the fan should be on all the time, is this correct?

TIA

You seem to have only one cooling fan, the earlier 406 had 2 and used the circuit shown on the web site I mentioned. When air con is on you should have the fan running at slow speed to provide cooling for the air con rad. The relays you mention are used in conjunction with the resistors to change the voltage applied to the fan an hence the speed. They are a notorious problem, corrosion being the cause. You should be able to prove the resistors by

1) a resistive check with and OHM meter with the connecting wires removed. 2) with a volt meter connected across the resistors when in circuit you should see a voltage. You cannot get a volt drop across a resistor unless the circuit is made and current is being drawn..