Fuse keep melting

[Kazuo]

One of the fuse in my fuse box in the engine bay keep melting.

 

It's the heater, 30amp. Not just the fuse plastic melt, but the plastic surround that particular connector also melting away.

 

However, the fuse doesn't blow, but somehow affect the functionality of my aircon blower.

 

Any idea what's wrong? or what could be the cause?

[Freifeit]

 

i had similar experience before. one way is to relocate the fuse away from heat source. another way is to replace the fuse casing with batter quality one. good luck!

 

 

[Kazuo]

but then mine is only that particular fuse...

[KVR666]

Kena before. Blower motor carbon brush wear out then somehow short circuit. Every time on blower only, doesn't matter with ac on or not, fuse blow. Check blower motor & associated wiring, could be short somewhere.

[Yeobh]

It's either loose fuse connection or there is a lose live wire grounded resulting in high current drawn.

[Simpleonly]

hi all digging this old post as i m facing the same problem... my fuse surrounding was melted but the fuse is not blow..

 

any particular workshop that is good in tracing such electrical problem?

all recomm is greatly apperciated!!

 

thanks!

[Yeobh]

Make there are no oversize fuse in the system.

[Good-Carbuyer]

One of the fuse in my fuse box in the engine bay keep melting.

 

It's the heater, 30amp. Not just the fuse plastic melt, but the plastic surround that particular connector also melting away.

 

However, the fuse doesn't blow, but somehow affect the functionality of my aircon blower.

 

Any idea what's wrong? or what could be the cause?

A fuse is meant to to protect more expensive items from damage by melting if overloaded

A fuse is sized not to melt within certain tolerance, especially if oversized

Can engage a Vehicle Electrician/Mechanic to check for you.

Ever had a colleague who asked for a replacement fuse every week. One day all wiring insulation on his motorcycle melted off. He spent a few hundreds to re-wire his bike (his bike also cost him a few hundreds to buy 2ndhand).

[Kb27]

A fuse is meant to to protect more expensive items from damage by melting if overloaded

A fuse is sized not to melt within certain tolerance, especially if oversized

Can engage a Vehicle Electrician/Mechanic to check for you.

Ever had a colleague who asked for a replacement fuse every week. One day all wiring insulation on his motorcycle melted off. He spent a few hundreds to re-wire his bike (his bike also cost him a few hundreds to buy 2ndhand).

A fuse is actually sized to protect the wirings.

 

That's why those who keep adding stuffs to the same wiring and upsize the fuse will run into problem.

 

Insulation will burn up and exposed bare wires become fire hazard... and poof...there's goes the car.

[Ender]

Probably a "bad" contact that cause a high resistance. There's no high current drawn, as evidence by your fuse didn't blow. But the same current use to operate your current going thru the "high resistance" of the bad contact is generating alot of heat (I2R). I have seen this with bad switches in my diy hifi amp days.

 

Clean you contact points an see how..

[Ender]

Probably a "bad" contact that cause a high resistance. There's no high current drawn, as evidence by your fuse didn't blow. But the same current use to operate your current going thru the "high resistance" of the bad contact is generating alot of heat (I2R). I have seen this with bad switches in my diy hifi amp days.

 

Clean you contact points an see how..

[Yeobh]

Without proper tools, it's very difficult for the so call auto electricians to rectify existing faults, they will just remove and add until the problem goes away. After all the time and component cost is for the car owners account. As for additional wires used for accessories, I always wonder, do the mech use Automotive Grade wires or just plain normal lamp wires.

[Admond]

Can try one of those automotive breakers, it is one-for-one replacement of the fuse that you can plug in. However, the item is taller hence have to be careful if it fits the height.

 

It's better than fuse where it detects overcurrent too. Anyway the source of your problem still remains n need to be solved

 

If it is loose connection or you ned to break the circuit faster before it burns, try a german brand item E-1048

 

 

 

[Yeobh]

You got the wrong guy, I am just one of the many armchair mech trying to help. If you are keen to use the auto current testers here are some of the latest available from the market.

Edited February 20, 2012 by Yeobh

[Chickensoup]

One of the fuse in my fuse box in the engine bay keep melting.

 

It's the heater, 30amp. Not just the fuse plastic melt, but the plastic surround that particular connector also melting away.

 

However, the fuse doesn't blow, but somehow affect the functionality of my aircon blower.

 

Any idea what's wrong? or what could be the cause?

Best that you consult a wireman....those workshop that service Alternators and Starter.

[Simpleonly]

thanks to all who reply...

 

to re-cap the problem:

 

1 )I got a used car and the rear air-con was not working, dealer sent it to WS to fix before handling the car to me.

2) on the day of getting the car, the rear air con was working at 1st, after a while the rear aircon was gone again.. the front air con is working fine.

2a) also found the the rear brake light & haz light was not working

3) dealer ask me to go to their WS for check again.

 

4)went to the WS 2 days later, WS open the fuse box and found the 1 of the fuse area melt (refer to pic 1)

5) from eye check the fuse dont seem to be blow..

6)from pic 1 u can see that 1 of connector "leg" was disconnect from the holder.. the "leg" was pull out together with the fuse.

 

7)the WS then wanted to remove the whole fuse box and open it up, i think they wanted to re-wiring the internal to another spare fuse connector.

8) but the WS had diffculty opening the fuse box..

9) so the solution by the WS was to extend the fuse connection out; by using 2 wire - 1st wire connect to the 12V input, 2nd wire connect to the original connector using soilder, this shall link to the downstream equipment/device. (refer to pic 2 & 3)

10)The original fuse was rated 30A, the WS use another 30A fuse but of bigger size (compare the melt fuse to the new fuse)

11) after connecting up, the air-con, rear brake & haz light was working again.

 

12)when i ask what is the main cause of this, the WS reply most prob cos by over current.

 

 

my main concern:

 

1) what actually cause the overload? I m very concern in finding the root fault and get it fix to prevent any more overcurrent.

 

2) is this "new" connection/wiring safe? as in term can it withstand the overcurrent shall fault happen again? refer to pic 4, the wire is getting a bit of press due to covering of the cover.. not sure if it will cut and expose the wire.

 

3)is it ok to use a bigger fuse with the same rating?

 

4)if this cause by lose connection at the original fuse connector, can i assume this will like be 1 off type of fault since the current soultion seem secure at the fuse.

 

 

[Briansoh]

Im no expert but it looks like a disaster waiting to happen. Anything that looks botched probably is a botched job. The manufacturers did not make it this way and it shouldnt be like this in the first place. I would suggest you abandon that workshop and find one better who is more capable of finding the root problem rather than just plastering over the fault.

 

Since they bypassed the positive side of the cabling and the car worked, I would suggest you start from there up to the battery/alternator to see whats wrong with that end of the cables.

 

FYI, my car had this problem when I got it as well thanks to some monkey and I spent many days pulling out all the crappy wiring. Most of it were melted and burnt and I was grateful that my car did not catch fire while on the highway or something. Rectify it fast and have a fire extinguisher of some sort ready in the mean time.

[Yeobh]

Here is new innovative short finding tester , very easy to operated and a time saver. It will literally do the moping up operation for the mech.

Edited March 9, 2012 by Yeobh