12V Electric Fan keeps blowing 10A fuse

[bilbo007]

Hi,


I just purchased a 12V 10" electric fan from Supercheap. Brand is Calibre Calibre Thermo Fan - 12 Volt, 10" - Supercheap Auto Australia.


On the box it states max current draw is 7.5A and it came with a 10A fuse. I connected the fan up as per the instructions and it keeps blowing the 10A fuse when I start the car. It doesn't blow the 10A fuse when the car isn't running. I know this isn't recommended but I put a 15A fuse in and it doesn't blow that fuse.


There are four wires to connect on the fan that come off the relay. 1. accessory (Green) 2. battery positive with a fuse inline (Red) 3. ground (Black) 4. power that connects directly to the fan (Blue).


I have wired the accessory to the car ignition, ground to the engine bay, positive to the battery then and there are blue and black wires running directly to the fan.


I've tested the following without the car running:


- Resistance test from electric fan ground to my battery negative terminal and its 0 ohms
- Applied 12V to the relay and tested resistance across it which was also 0 ohms
- Resistance test from blue to black (across the electric fan) 0 ohms
- Battery positive to ground 0.04 ohms
- ACC to ground 0.04 ohms


I can't workout why the fan is blowing a 10A fuse when the car is running. I'm concerned that I will burn out the fan with it drawing over 10A. Does anyone have any other suggestions that I could try to troubleshoot?


Thanks,

 

[telectrix]

measure the current with a d.c clamp meter. try an anti-surge fuse.

 

[bilbo007]

Thanks for your help Telectrix. I bought a clamp meter and without the car running the fan draws 7.5A, with the car running at 14V it draws around 8.8A which is correct when comparing current at 12 and 14V.

I couldn't find a 10A anti-surge fuse, do you think it should be alright to leave the 15A in there?

Thanks

 

[telectrix]

anti-surge fuses come in the round glass type 20mm or 30mm. fit into an in-ljne holder. the 15A should be OK, if only as a temp. measure.

 

[Marvo]

Fuse protection is worked out with respect to the size of the wiring that's been used. If the wiring cross-sectional size is 1mm² or larger then a 15A fuse should be fine.

The other option is to replace your existing fuse with a resettable thermal circuit breaker which would be more tolerant to the fans start current.

Here's a few options;
http://autoelectricalpartsuk.co.uk/...t_Breakers/038010_10_Amp_Circuit_Breaker.html
http://www.ebay.co.uk/itm/Circuit-B...-5A-30A-Marine-Rally-Automotive-/321268071405
http://www.digikey.co.uk/product-highlights/uk/en/e-t-a-1610-thermal-circuit-breaker/1978