On my 2001 2.0 Hdi c5 the rad fan does not come on so I thought I'll have a go. Took the fan off and gave it a clean and a squirt of wd40 and attached to a spare battery and it ran like a good un. I cleaned all the relays. I then put it all back together and started the engine and let it run for ages. I switched the aircon on and the fan didn't move. I disconnected the lead into the fan and checked the loom and it was giving power so why wasn't the fan turning. I checked the voltage and it was giving just under 12 volts. Put the fan back to a spare battery and it worked fine. Connected it all back together and nothing.
I'm flummoxed, any thoughts please.
Rad Fan Odd Problem
Moderator: RichardW
More confusion now. With the engine running and the aircon on I get 12v from the car loom measured on a multimeter. I put a 12v test bulb on the loom and it doesn't light (it worked on a check test to the battery). I reconnected the voltmeter and got 12v but this time I connected the test lamp to the clips on the multimeter and the light didn't light and the voltage dropped to zero, I disconnected the test lamp and the voltage returned. What is going on?
Any help please.
Any help please.
Haven’t been there yet, but it may be that the 12V is a permanent supply to the fan, while the switching is done on the earthy side with the relay and the resistors.
If possible, try to measure where the motor’s earth wire goes.
If it doesn’t go straight to earth, it then goes to the relay box for switching.
If possible, try to measure where the motor’s earth wire goes.
If it doesn’t go straight to earth, it then goes to the relay box for switching.
2002 C5 2.0i AL4 230,000 km 76372389
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Does the C5 have a Bitron unit?
I posted elsewhere on the Forum about the op-amp drivers inside a climate control module; it's possible similar effects could be felt with a Bitron fan controller if the relay switching terminals are making poor contact - the signal amplifier could cook or become dry jointed.
I posted elsewhere on the Forum about the op-amp drivers inside a climate control module; it's possible similar effects could be felt with a Bitron fan controller if the relay switching terminals are making poor contact - the signal amplifier could cook or become dry jointed.
Fixed mine today. If you take the tie clip off and unwrap the insulation you can see the flow of power much easier.
Two blue wires come from the main loom and one of these goes straight to one side of the Fan.
The other one also goes to the Fan but via the High speed relay first. This relay is blue in colour.
My Hi speed fan was working okay so I knew that this circuit was good.
Half way along its route from the hi speed relay to the fan, the blue wire also branches off into the medium speed relay and this was also showing 12 volts when energised. the blue wire then goes to the 2 resistors and then into the low speed relay. My current flow went into the grey resistor but didn't come out the other side so I tested it for continuity and the coil inside was good, but the small diode type thing wad not. I shorted across where the diode was and the circuit is now complete to the low speed relay and on to the fan. The haynes diagram was a great help in understanding it.
Two blue wires come from the main loom and one of these goes straight to one side of the Fan.
The other one also goes to the Fan but via the High speed relay first. This relay is blue in colour.
My Hi speed fan was working okay so I knew that this circuit was good.
Half way along its route from the hi speed relay to the fan, the blue wire also branches off into the medium speed relay and this was also showing 12 volts when energised. the blue wire then goes to the 2 resistors and then into the low speed relay. My current flow went into the grey resistor but didn't come out the other side so I tested it for continuity and the coil inside was good, but the small diode type thing wad not. I shorted across where the diode was and the circuit is now complete to the low speed relay and on to the fan. The haynes diagram was a great help in understanding it.
