Author Topic: Alfa 75 heater fan problem...  (Read 16251 times)

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75Guy

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Alfa 75 heater fan problem...
« on: August 18, 2010, 02:35:51 PM »
Hello all, I am at my wits end trying to solve a problem preventing my car from being registered. It's the only thing the mechanic said that needs to be fixed before I can be driving it every day so understandably I'm rather tense right now.

The 75 is a 1985/6 2.5 V6 with air con of the same style used in the same year 90's.

The fan for the heater must be able to blow air onto the windscreen (defog purposes). Turn knob for heater fan and theres nothing.

Heres what I have done:

Checked fuses with test light: aok.
Checked switch with test light: receives power as it should.
Warm car up and hit the fan: nothing.

All other heater related controls work fine. That makes me suspect its the switch but as above, as the switch is changed power is as expected.

Really all I need is it to blow air, thats it even if it is like an asthmatic.

Any help would be great.

dehne

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Re: Alfa 75 heater fan problem...
« Reply #1 on: August 18, 2010, 05:53:11 PM »
i have the same prob with my 90, a mate had the same with his 90 and he fixed it it is something to do with the switch behind the unit im pretty sure he swaped the wires around so the fan then was either on or off no adjustment, ill try find out and post it if someone else has not already done
now
1x 85 mdl road 90
2013 Giulietta 1.4
2015 Launch Edition Giulietta
Past
Multiple Alfa 90’s, Alfetta’s and 147’s

75Guy

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Re: Alfa 75 heater fan problem...
« Reply #2 on: August 18, 2010, 06:32:57 PM »
That would be beautiful. I have had a stress headache all day from this problem...

For a bit I was so mad with it I was going to give up and buy a corolla  ;)

dehne

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Re: Alfa 75 heater fan problem...
« Reply #3 on: August 18, 2010, 06:36:39 PM »
thats not mad thats completly INSANE
now
1x 85 mdl road 90
2013 Giulietta 1.4
2015 Launch Edition Giulietta
Past
Multiple Alfa 90’s, Alfetta’s and 147’s

75Guy

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Re: Alfa 75 heater fan problem...
« Reply #4 on: August 18, 2010, 06:45:07 PM »
I have a absolute love/hate relationship with this car. Today it was all hate. Yesterday (driving to the mechanics from twisty country roads...) it was all love.

I can only assume the balance will shift once I can drive it every day.

P.S Also wouldn't buy a corolla, a twinspark 75 maybe if I went through this again though...






Typhoon90

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Re: Alfa 75 heater fan problem...
« Reply #5 on: August 18, 2010, 10:06:02 PM »
With older cars, every time I have had an issue like this, it has been the resistor pack for the fan motor. In fact, I repaired this exact problem on my 90 on the weekend.
The first thing you need to do is establish that it is the resistor pack. The easiest way to do this is to use  a test lamp and check that the blower control knob has power going in to it and out of it when you turn the knob.
 You will need to find the resistor pack if it tests good. On the 90, it is up and behind the bottom of the blower/heater casing. If you are REALLY skinny, you might be able to get to it from the passenger's foot well. At the least you will need to remove the console and find a very bright light. The resistor pack is about the size of  a box of matches and clips into an opening in the side of the blower case. There will be a metal spring clip at the bottom edge holding it in, it is  a circuit board with wire coil resistors that sit into the heater box. The resistor pack will have four wires going to it, one will be  a big red wire, a purple, grey and yellow. I took a photo as luck would have it:
 

 I couldn't get a photo of the resistor pack installed, all you could see was the spring clip.
 So, you have two options here. One is to join any of the other wires to the red wire to get the blower working, or, spend an extra 10 minutes and fix the resistor pack. The big red wire in my photo is the wire that powers the blower motor, the three other wires feed power from the rotary switch into one of three resistors, which then flows into the red wire, giving you three speeds. See how the red wire has  a piggyback terminal? Pushing any of the other three wires onto this terminal will give you full blower speed in only one switch positon, but fixing it properly is easy if you are this far in.
 The resistor pack on most all cars is placed into the heater box, to ensure a cooling air flow over the resistors. With age, they tend to collect leaves etc up against the resistor wires, which overheats them and they either break or burn out. If you look at the resistor pack, you will see a broken wire somewhere, simply replace it, or if it's  a coiled wire, bend it then reattach it to where the old piece has broken off it's terminal. Changing the length of the wire changes the resistance, and hence blower speed on that fan setting, but it's rarely noticeable and you still get three distinct speeds. Once you have it repaired, plug the wires back in and test it with the resistor pack out of the case. You will find a whole heap of leaf litter blows out of your heater box through the resistor pack hole, you can help it out by digging it out with your finger.
 Now, bear in mind the description was specific to my 90 with regards location of the heater pack, but I am betting that Alfa Romeo didn't change much between the 90 and 75, they were both 160 series cars and shared a lot of components and auto makers love reusing stuff that already works well.
 I hope this helps, it sounds like  a much worse job than it is, but believe me, by far the hardest part is getting to the resistor pack in the first place, and the convenience that a working blower fan brings makes it well worth the effort!

 Regards, Andrew.
« Last Edit: August 18, 2010, 10:11:00 PM by Typhoon90 »

75Guy

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Re: Alfa 75 heater fan problem...
« Reply #6 on: August 18, 2010, 10:11:25 PM »
Thanks so much for that informative post! Really very helpful.

Tomorrow I'll have a crack at it. If its a case of having the dash out that's no problem - I've had the entire dash out before and once you have done it once it's not all that bad.

I'll let you all know how I go.

Cheers!


Typhoon90

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Re: Alfa 75 heater fan problem...
« Reply #7 on: August 18, 2010, 10:31:21 PM »
You'll just need the console out at worst, you should be able to see what you are doing once it's out. I'd consider pulling the passenger's seat out if you can, it makes access easy, just lay down on the floor with head up under the dash.
 The easiest way to find the resistor pack will be to follow the four wires from the back of the rotary blower speed control, or work back from the red wire on the blower motor.

 Regards, Andrew.

Anthony Miller

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Re: Alfa 75 heater fan problem...
« Reply #8 on: August 19, 2010, 07:30:43 AM »
Well done Andrew, sound advice. Alfa engineers were a lazy bunch in the 70's & 80's (the 75 is just a Joolie on steriods) they used the same switch gear all the way through. Two of my joolies suffered from the same problem and were rectified with replacing or repairing the resistor pack. Good luck 75Guy
Now-  '99 156 2.5l V6 (rosso)
         '88 75 3.0l V6 (grigio)
Then- '81 Giulietta 2.0l transplant (ol whitey)
         '82 Giulietta 2.0l transplant (ol brownie)
         '82 Giulietta 2.0l TS transplant (ol red)

75Guy

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Re: Alfa 75 heater fan problem...
« Reply #9 on: August 19, 2010, 04:05:54 PM »
EUREKA!

Everything fixed!

My resistor was a different design to the one you posted but was similar enough to work a solution.

Thank you so much Typhoon and if I ever meet you in person beers will be on me  ;D

Typhoon90

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Re: Alfa 75 heater fan problem...
« Reply #10 on: August 19, 2010, 05:26:27 PM »
Great that it worked out!

 Regards, Andrew.

oz3litre

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Re: Alfa 75 heater fan problem...
« Reply #11 on: August 19, 2010, 06:36:51 PM »
EUREKA!

Everything fixed!

My resistor was a different design to the one you posted but was similar enough to work a solution.

Thank you so much Typhoon and if I ever meet you in person beers will be on me  ;D

Did you have to take the console out or were you able to get at it from underneath? My fan has stopped working too. I have a parts car with a fan that works though.
2008 159 TI 2.4 JTDM Sportwagon. Stromboli Grey. Wife's daily driver.
2004 GT 3.2 V6, Stromboli Grey. My daily driver.
1989 75 3 litre, black.
1988 75 3 litre V6. Red. Son's daily driver.
2000 156 Twinspark manual. Cosmo Blue. Daughter's daily driver.

75Guy

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Re: Alfa 75 heater fan problem...
« Reply #12 on: August 19, 2010, 10:08:27 PM »
Basically what I did was remove the centre console, disconnected the radio and sat it to the side. Then I reclined the passenger seat, laid down and followed the wires until I found the resistors. Hardest part was getting it off theheater itself - stuck on pretty tight.

Apart from that it was easy - as soon as you know what your looking for its very, very easy.

For a quick guide to getting the console out go here:

http://www.users.on.net/~craigf/heaterconsole.htm

cheers!

dehne

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Re: Alfa 75 heater fan problem...
« Reply #13 on: August 19, 2010, 11:10:48 PM »
i also have done mine today i left every thing in tacked as i looked at the race car first found where it was then just went straight to the source and bang away it went, shlt i forgot how bloody hot the heater was
now
1x 85 mdl road 90
2013 Giulietta 1.4
2015 Launch Edition Giulietta
Past
Multiple Alfa 90’s, Alfetta’s and 147’s

bteoh

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Re: Alfa 75 heater fan problem...
« Reply #14 on: August 20, 2010, 01:03:07 PM »
Hey Andrew,
I wish I had read your post a few days earlier as that is what happened to mine. Ripped out the whole dash etc on wednesday and found the resistor pack . However, someone had modified it and soldered a 15Amp fuse between the slightly thicker coil. The fuse blew and that's why the fan stopped working?
Any idea why anyone would solder a fuse between the resistor coil? (There's 2 coils on the pack - a slightly thicker coil and a thinner one; the fuse was linked to between the thicker coil) Will tyr to take a pic when I can.
Anyway, will try to blow out any debris in the box - there's a rattle when the fan is on......  :)

Cheers,
Brian