Mitsubishi L200 Fan Heater blower Fuse keeps blowing

blown fuse..burnt up resistor block..bad ground..

sound's like a earthing problem , try a continuity test from blower LIVE to chassis , if get continuity then def got a wiring problem , very difficult to diagnose without seeing vehicle , get a auto electrician

could be the fuse or the actual heater blower system an the only way to acces the system is by removing your dash i would start by replacing the fuse then going from their

I would disconnect your blower motor resistor then try fuse again, if it does'nt blow then it is either blower motor or resistor,these resistors are common for going bad/and or blower motor. Good luck let me know if you need more info or if this didn't fix it, I will research it more for you

The three most common problems for heater fans are

1. Burned-out blower motor resistor. This is usually located on the engine side of the firewall. Sometimes one section of the resistor is burned out but others are still good, so the blower only works on the highest speed settings. If you have a burned-out resistor, check the blower bearings to make sure they are not stiff and causing the motor to draw too much current.
2. The blower is actually working, but either the intake vent is plugged (I've seen vehicles with the heater core completely blocked by dirt, leaves and insects that came in through the vent), or the heater door is stuck closed.
3. The motor bearings have gone bad (see # 1). This can cause the fuse to blow, although the resistor usually fries first.

I'm not sure how your car's cabin environmental control system is fused. Check any fuse that might apply, such as Vent/AC, HTR, FAN, etc. Generally you can identify the state of a blade-type fuse by inspection without removing it. If you have a blown fuse, check the blower motor before wasting money on a new fuse that will probably blow. Like any fan, it's supposed to turn easily, and there should not be any roughness or side-slop in the bearings.

check switch at contacts for continuity. Check heater blower fuse and relay If fuse is blown and new fuse blows right away there is a short to ground or power. (either in cab or under hood in power distribution box). Check wiring running to blower for possible short. Check blower.

What can go wrong with a blower motor?
There are several things that may cause your blower motor to stop working. The simplest cause would be a blown fuse. If you replace the fuse and it quickly blows again, then you probably have an electrical short. Disconnected wires on the exterior of the blower motor can also cause it stop working, and if your blower motor gets dirty, it can get clogged or muddy which keeps the fan blades from spinning.

How do I test my blower motor?
When you are troubleshooting your blower motor, it is best to start by running the air conditioning or the heater to see if you can hear the sound of the fan. If you can hear the fan, it could be clogged or corroded with dirt. If you do not hear the fan, then you may have a bad resistor, blown fuse, or a loose wire. Next, you should replace any blown fuses in your car's fuse panel and try to start the blower motor again. If another fuse blows right away, you have an electrical short. If it doesn't blow out and the motor is still silent, then something else is wrong. In the case where the fuse lasts for a little while as the fan spins but then the fuse blows again, that usually means you need to replace the brushes on the motor. Finally, you can pull the motor out and visually inspect it for loose wires. If you don't see any and still want to test, try hooking it up to the battery to see if the motor will start. If all these tests still find you with a dead blower motor, it's definitely time to replace it.

How do I replace it?
Usually located under your vehicle's instrument panel, the blower motor can be removed and replaced. You'll need to disconnect the blower motor connector and remove the retaining screws holding it into place. Detach the fan retainer clip from the motor shaft that's located in the center of the blower wheel. You may need to save that piece if you are not replacing the whole motor. Inspect your new motor to ensure nothing is broken and the blades can properly spin. Re-attach the fan retainer clip, the retaining screws, and the connector so you can test your new blower motor out.

More than likely the fan motor its self is short to ground try to unhook the wires to the fan motor and install a new fuse and then turn the fan on with the wires removed and if the fuse is still good you know it is the fan motor its self

Replace the fan resistor located under dash near passenger side on the side of the heater box.

Check the blower motor speed control resistor, and all connections for good fitment.