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Discussion Starter #1
Good Afternoon all.

As the weather is changing here my thoughts turn to the fact that when I switch on my heater/blower switch it blows a fuse.

I ordered a new switch from classic alfa and the one that arrived had 4 prongs on the back and also does not fit in the hole
It's a left hooker 1987 graduate so would someone be kind enough to send me a picture of the back of their switch so that I can replicate the wiring.
I am wondering if the switch that I have in now is wired up incorrectly and hence its blowing the fuse when I turn it on.
Any advice will be much appreciated as I am not great at electrics but since owning the Alfa have certainly learnt a bit more.
I fitted a nice blaupunkt last week and it works !!
Thanks
Steve
 

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But Mad North-Northwest
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Generally I wouldn't expect a bad switch to blow the fuse, that'll usually be the fault of some wiring downstream.

Check the yellow and yellow/black wires out of the switch and see if either has a short to ground. The yellow just goes to the motor, the yellow/black goes to the motor and the light in the dash.

May also want to stick your finger up through the floor vents and make sure the blower motor turns freely. I don't think a stuck motor will blow a fuse but I could be wrong, and it's a common issue anyway.
 

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Generally I wouldn't expect a bad switch to blow the fuse, that'll usually be the fault of some wiring downstream.

Check the yellow and yellow/black wires out of the switch and see if either has a short to ground. The yellow just goes to the motor, the yellow/black goes to the motor and the light in the dash.

May also want to stick your finger up through the floor vents and make sure the blower motor turns freely. I don't think a stuck motor will blow a fuse but I could be wrong, and it's a common issue anyway.
I agree with you about the short not being usually the switch and generally, a stuck motor does not blow the fuse in my experience.
 

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I would check your wires. To see if you have a short you can take your positive wire from the switch and measure the resistance to a ground. Id also make sure there's no coolant in the bottom of the heater box leaking on the fan.
 

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I ordered a new switch from classic alfa and the one that arrived had 4 prongs on the back and also does not fit in the hole
if it doesn't even fit in the hole you are off to a poor start;)
just send it back.

which did you order, this one?
switch front.jpg switch reverse.jpg

show us a pic of the back of your original switch. Basically the alfa switch is a simple OFF/SLOW/FAST switch

the two pinks are power: connect to one spade
single yellow wire is high speed
two yellow/blacks, one is low speed & the other is the dash indicator light: connect to one spade
so I guess the 4th spade stays empty
maybe this wiring snippet is of help?
heater switch.jpg

in case the problem is not the switch:
let's presume you are talking fuse #7...correct?

power comes into the switch via the cigar lighter
check the lighter, perhaps just unplug it and then try the heater fan (with your old switch)
 

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Discussion Starter #6
if it doesn't even fit in the hole you are off to a poor start;)
just send it back.

which did you order, this one?
View attachment 1666628 View attachment 1666629

show us a pic of the back of your original switch. Basically the alfa switch is a simple OFF/SLOW/FAST switch

the two pinks are power: connect to one spade
single yellow wire is high speed
two yellow/blacks, one is low speed & the other is the dash indicator light: connect to one spade
so I guess the 4th spade stays empty
maybe this wiring snippet is of help?
View attachment 1666630

in case the problem is not the switch:
let's presume you are talking fuse #7...correct?

power comes into the switch via the cigar lighter
check the lighter, perhaps just unplug it and then try the heater fan (with your old switch)
Hi

That is all excellent information. I have a bit of time to spare now being in Lockdown so will have a look tonight and report back.

I have now also lost the rocker switch bit it was this one EL044 FAN ROCKER SWITCH - SPIDERS 86-93

Thanks

Steve
 

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Discussion Starter #7
Hi

That is all excellent information. I have a bit of time to spare now being in Lockdown so will have a look tonight and report back.

I have now also lost the rocker switch bit it was this one EL044 FAN ROCKER SWITCH - SPIDERS 86-93

Thanks

Steve




I will take some pictures in a minute but an interesting thing just happened. I put the original switch back in and when I turned it to the second click of the toggle the heater light appeared on the dash which I had never seen before and then the fuse blew. I then took the wires off the back of the cigar lighter and it still blew again. I am guessing that the off position is to the left and when you click once right and then right again that's the second stage ?

I did replace the cigar lighter a while back and don't think it actually works so perhaps I need to look at that again. Will post a picture of the wiring on the lighter too in case that is wrong !

Thanks

Steve
 

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Discussion Starter #8
I will take some pictures in a minute but an interesting thing just happened. I put the original switch back in and when I turned it to the second click of the toggle the heater light appeared on the dash which I had never seen before and then the fuse blew. I then took the wires off the back of the cigar lighter and it still blew again. I am guessing that the off position is to the left and when you click once right and then right again that's the second stage ?

I did replace the cigar lighter a while back and don't think it actually works so perhaps I need to look at that again. Will post a picture of the wiring on the lighter too in case that is wrong !

Thanks

Steve
 

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But Mad North-Northwest
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The dash light should come on dim when the switch is set to low and bright when it's set to high.

The power feed comes from the lighter, but that can't cause the fuse to blow when you flip the heater switch. You need to check the yellow and yellow/black wires out of the switch with an ohmmeter to se if you have a short to ground. Since the light circuit seems to work okay I suspect you're going to find your motor (or the wiring to it) has a short.
 

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Hi

That is all excellent information. I have a bit of time to spare now being in Lockdown so will have a look tonight and report back.

I have now also lost the rocker switch bit it was this one EL044 FAN ROCKER SWITCH - SPIDERS 86-93

Thanks

Steve
It looks like you ordered the correct one according to their site. Have you spoken with anyone there about this?
It does show 4 connections on the site.
I ordered one recently from a vendor in the USA and while it was not like the original, it did fit. Either Centerline or Vick. I don't recall
 

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I will take some pictures in a minute but an interesting thing just happened. I put the original switch back in and when I turned it to the second click of the toggle the heater light appeared on the dash which I had never seen before and then the fuse blew. I then took the wires off the back of the cigar lighter and it still blew again. I am guessing that the off position is to the left and when you click once right and then right again that's the second stage ?

I did replace the cigar lighter a while back and don't think it actually works so perhaps I need to look at that again. Will post a picture of the wiring on the lighter too in case that is wrong !

Thanks

Steve
Has your 87 got blade fuses or bullet fuses?
that no. 7 fuse should be 10A btw.

yes, off is when the left side is pushed down.....then once to right is low and again to right is high.

1: with ignition ON, do you have 12V at the pink wires at the toggle switch?
2: does the fan motor even work?: look up under the dash above your pedals...there you see 4 wires connected to the fan motor. First check those wires are connected properly
Then.....apply 12V to the blue wire, does fan work? Now apply power to the red wire, does other fan speed work?
3: If the fan doesn't work, then manoeuvre those side vents half open and put your fingers in there....can you spin the fan?
4: if fan spins with fingers, but not with power direct, then check the ground...it is on the other side of the heater, quite hidden.

(the yellow and the yellow/black coming into that 4 post terminal should have 12V with toggle switch pushed to relevant position, low or high, but of course that is impossible for you to test as your fuse blows)
fan wires 90 spider.jpg

remember the pink wires (power) join up behind the centre console in a big 15 pin connector, G84a
worth checking that .
 

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Discussion Starter #12
Chaps

I think I had better get the cigar lighter wired up correctly before I do too much else. I have attached a picture of the lighter it is just a cheapie that I bought from a local shop. There is a socket with two pink and two black with a red coming out of the other end and a black that spurs off into two. There is another lead that you will see next to it that has two black and whites going to it and that one was just dangling so if you can tell what goes where I can eliminate the cigar lighter. I am a bit thick on this side of things so really appreciate the help !

The cigar lighter also has a plug on in for the light surround which I did not wire up so perhaps it should be in order to make the circuit.

I have a voltmeter but would not know how to check to see if I have a short to ground ?

Heater plug looks as you say it should so nor worries there.

Thanks

Steve
 

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Chaps

I think I had better get the cigar lighter wired up correctly before I do too much else. I have attached a picture of the lighter it is just a cheapie that I bought from a local shop. There is a socket with two pink and two black with a red coming out of the other end and a black that spurs off into two. There is another lead that you will see next to it that has two black and whites going to it and that one was just dangling so if you can tell what goes where I can eliminate the cigar lighter. I am a bit thick on this side of things so really appreciate the help !

The cigar lighter also has a plug on in for the light surround which I did not wire up so perhaps it should be in order to make the circuit.

I have a voltmeter but would not know how to check to see if I have a short to ground ?

Heater plug looks as you say it should so nor worries there.

Thanks

Steve
You may be on to something with that aftermarket cigar lighter and wiring,
As far as your meter, disconnect the battery and test in the ohms setting to test for grounds.
I assume that the clock is not working either?
 

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But Mad North-Northwest
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Again, don't focus on the lighter. It is upstream power-wise from the switch and thus can't cause the short you're seeing. Besides, you unplugged the lighter and still had the short, that eliminates it as a potential problem.

Set your voltmeter to measure Ohms. Connect the black lead from the voltmeter to a ground on the body of the car somewhere. Disconnect the yellow/black and yellow wires from the switch, and then measure each wire one at a time by connecting the red lead to it. You should probably measure a couple Ohms resistance on each...if it's lower you likely have a short. Report back with what you get.
 

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Discussion Starter #15
Chaps

I think I had better get the cigar lighter wired up correctly before I do too much else. I have attached a picture of the lighter it is just a cheapie that I bought from a local shop. There is a socket with two pink and two black with a red coming out of the other end and a black that spurs off into two. There is another lead that you will see next to it that has two black and whites going to it and that one was just dangling so if you can tell what goes where I can eliminate the cigar lighter. I am a bit thick on this side of things so really appreciate the help !

The cigar lighter also has a plug on in for the light surround which I did not wire up so perhaps it should be in order to make the circuit.

I have a voltmeter but would not know how to check to see if I have a short to ground ?

Heater plug looks as you say it should so nor worries there.

Thanks

Steve

Have just order the new lighter from Alfaholics as only £15

I have blade fuses and will check to see if I can spin it.

Have printed off what you told me to do so will also try the wires.


Thanks

Steve
 

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Discussion Starter #16
Next Update

Its a LHD so I got into the passenger side twisted around nearly broke my back but as stated got to feel the white blades which were stuck. I got a screwdriver up there and now she in spinning. I turned on the switch and got a low light on the dash then went to the second stage got the brighter light and then bang went the fuse but still only a 7.5amp so should I try with a 10amp or do we still have an underlying earth problem do you think !

Progress though !!!
 

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But Mad North-Northwest
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Okay, progress. After you got it unstuck, did the fan spin at all when you turned on the switch? I'm guessing not.

If I had to guess I suspect you've got a short in the motor. The low speed circuit passes through a resistor at the motor, and that's probably enough to keep from popping the fuse. When you switch it to high that resistor isn't in the circuit and the fuse blows.

Try the test above with the voltmeter, see what resistance you measure. In thinking about it, you should also test at the heater box itself. There are two connections on the lower left side for the fan: disconnect the wires from the front of this and measure resistance to ground at each of the two terminals: this'll directly measure the motor without having the light circuit involved.
 

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Discussion Starter #18
I have power at the pink wires on the heater switch with ignition on so that is good.
I will run an independent live wire up to the connection on the fan and see if it works on low & high.
Now the battery light does not come on when ignition is on and the alternator light is on when its running. The only thing I have done is removed the red repay top left of the fuse box and put it in again !!
Never rains when it pours as they say
 

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But Mad North-Northwest
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I will run an independent live wire up to the connection on the fan and see if it works on low & high.
No, no, no. If there's a short in the motor and you run another +12V wire to it, you have a very real risk of melting that wire or doing other damage.

Do the voltmeter test I explained above to figure out where the short is. If you don't have a digital voltmeter then buy one: they are not that expensive and are an invaluable Alfa tool. If that test isn't something you feel you can do then I'd really recommend taking it to a pro.
 

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Discussion Starter #20
Ah I see

I have a meter so will do as you say and come back to you.

You know the saying ' A little Knowledge is dangerous ' Thats me !!
 
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