Gransport 2007 blower fan not going off when ignition turned off

[Tony h]

Ok. Do you have 12v at the cigarette lighter socket with the ignition off? If I recall correctly, this was not powered on my GS when the ignition was off.

Hi Zep
When I measured the voltage in the cigarette lighter before turning the ignition to Acc position it read zero V then 12v at key position Acc when I turned the ignition off again the cigarette voltage went to 5.8v and stayed there, its almost as if there is an earth problem which is feeding back somewhere

 

[Zep]

Hi Zep
When I measured the voltage in the cigarette lighter before turning the ignition to Acc position it read zero V then 12v at key position Acc when I turned the ignition off again the cigarette voltage went to 5.8v and stayed there, its almost as if there is an earth problem which is feeding back somewhere

Ah ha! Perhaps this is enough to keep the HVAC controller alive and your fan going but not some of the other kit.

At this point I’d pull relay C and check the resistance across the contacts when de-energised. It might be that the contacts are not clearing fully when off, giving a high resistance connection, hence the low voltage.

 

[Tony h]

Fuse 5 is shown as Air Conditioning and Ventilation system and fuse 45 also lists Air Conditioning and Ventilation, but shows it as cut out during starting (I.e. fed by relay C). The suspicion is that the controller is doing something it shouldn’t, running the fan when off. Either because it thinks the ignition is on, or because it’s broken.




There aren’t any diagrams I am aware of, so the next option to that is probably the preferable one.

Hi Zep both the fuses mentioned above are Ok. Zep you mention the controller which controller is this? the Air con?

 

[Tony h]

Ah ha! Perhaps this is enough to keep the HVAC controller alive and your fan going but not some of the other kit.

At this point I’d pull relay C and check the resistance across the contacts when de-energised. It might be that the contacts are not clearing fully when off, giving a high resistance connection, hence the low voltage.

Hi Zep I have tested both these and both coil resistance readings are the same 80 odd ohms and the contacts are showing open circuit. In addition I swapped the relays over but still no change

 

[Zep]

Now I’d look at the quality of the earth connections. Check the resistance of the ground in the cigarette lighter to a clean ground somewhere else on the car. Plus I would see which of the two HVAC supply fuses, when removed, stops the fan. Maybe find the earth point in the footwell and clean it up.

 

[Tony h]

Thanks so much for your advice, will do this over the next day or so. I have checked the battery earth and that looks good but it only takes a small bit resistance to cause a problem and as I have had water in the footwell from the anti con drain last year there is a chance that there is corrosion in this area. Thanks for all of your support appreciated.

 

[Zep]

No problem, I’m sure you’ll get there.