heater unit / fan not working - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 13 (permalink) Old 10-04-2016, 09:47 AM Thread Starter
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heater unit / fan not working

Hi everyone

This is my first post in this forum. I already read a lot of interesting threads and hope to be able to contribute in the future .

I have a question regarding the heater unit in my 75. My fan is not working at all. The heating does though. I searched in the technical and model specific forums and already got some hints or ideas what it could be. Some people faced the problem that leafs and other stuff is getting stuck in the fan. This is not the case, it rotates freely when turned by hand. I also check the fuse and it seems to be fine.

I wonder if maybe the fan motor is broken. Unfortunately I have no 12V source to check if it still working, but that would be the next step. I also saw that there seems to be one cable missing on the back of the fan knob that lets you choose how strong it should blow. Will post a picture later on.

Do you have other ideas what could cause the vents to stop blowing?

Thank you for your help!

Last edited by papajam; 10-23-2016 at 04:34 AM. Reason: correct title spelling for search function
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post #2 of 13 (permalink) Old 10-04-2016, 10:10 AM
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Why no 12v source you have the 75 don't you? Can you access the wires to the fan motor? There is a three wire resistor in system too for different fan speeds.

Does your 75 have A/C too or just heater?

Ciao, Alfisto Steve
Lakeland, Florida
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Alfa Semi-Daily driver: USA model - BB2 1991 164S Black Beauty II ALFISTO [U]

[U] BB1 1991 164L w/S engine and A/T now excess to inventory [U]

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post #3 of 13 (permalink) Old 10-04-2016, 11:08 AM
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I'm posting this for Jonas because he cannot yet post links.

We found some wires coming from the heater unit. Below a picture.



We also wondered, if on the back of the fan knob there should be one cable more connected. It seems like there is one missing..



Regarding the three wire resistor. The fan doesn't work at all. Do you think the fan won't work at all if this resistor is broken?

Learning, learning..
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post #4 of 13 (permalink) Old 10-04-2016, 05:21 PM
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What model and what year 75 do you have?

Jonas

What year and what model is your 75? Most European 75's have a very different heater assembly than the ones sold in the USA and other countries.

USA 75s (Milanos) all came with Air Conditioning and a big combined box which housed a heater core, an air conditioning evaporator core, a single element squirrel fan, and various ducting. Th box(and others like it) is called a HVAC box. HVAC meaning Heating, Ventilation, & Air Conditioning. The HVAC box was actually made by BEHR of North America in Dallas Texas and shipped to Italy for installation in Milano's.

Most European 75 came with a simpler box with just a heater core and a double element squirrel fan.
If your fan was working one day and then not the next, then I strongly suspect that the fan motor has indeed failed. In general ten to twelve years is a good life span for a heater / ventilation fan.
In regards to the fan resistor, the way they normally work is that at the highest fan speed the resistor is not involved at all. So even if the resistor was broken, the fan should operate at the highest setting. high.

Do you have the factory service manual for your 75? If not, I may be able to get it to you.

Hope this helped,
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post #5 of 13 (permalink) Old 10-04-2016, 11:20 PM Thread Starter
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Hey Milanoguy. Thank you for your input.

I'm Sorry, I forgot to clarify this. My 75er is a European Model TS 2.0 without AC, year 1991.

I bought the car with not working heater / ventilation fan. So it is possible that the fan is broken - 12 year already passed . Do you know which wires to connect if I want to test if the fan is working?

I do have the service manual for the 75er and already had a look, thank you for offering it. Unfortunately the troubleshooting area does not cover my case. However I used it to disassemble the middle console and dash and get an idea how the heater unit looks like.

Jonas
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post #6 of 13 (permalink) Old 10-05-2016, 06:44 AM
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Check the GROUND. Mine disconnected and hooked it up and ran fine. The ground wire is screwed to tunnel under the heating unit.

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post #7 of 13 (permalink) Old 10-05-2016, 09:56 AM
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If you can see heater blower motor wires what color are they. Usually black or green are ground and red, red/black or pink are power source. apply 12v to power wire and ground other wire and see if fan motor will spin if it spins freely with no power.

Is it a motor in center with two hamster/squirrel wheels one on each end?

Milano with A/C had pink power wire and black ground wire for blower motor.

Ciao, Alfisto Steve
Lakeland, Florida
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Alfa Semi-Daily driver: USA model - BB2 1991 164S Black Beauty II ALFISTO [U]

[U] BB1 1991 164L w/S engine and A/T now excess to inventory [U]

Daily driver and parts hauler but not car hauler 2004 Jeep Grand Cherokee Overland 4.7L H.O. V-8

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post #8 of 13 (permalink) Old 10-05-2016, 02:03 PM
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Hey Alfisto

Yeah its the one with the two hamster/squirrel wheels.

We will look into it thanks a lot!
-Alessandro

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post #9 of 13 (permalink) Old 10-10-2016, 12:59 PM Thread Starter
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I tested the fan in the meantime. It spins up freely when connected directly to a power source. So it can't be the fan itself.

As Alfisto Steve mentioned earlier there is the heater resistor. I found another thread with a discussion where people talk about replacing broken open coil resistors on the heater resistor board. So next I will check this resistor coil - when I had a look this weekend, I didn't realise that you can remove it and that there are the coil resistors on the back of the board.

Does anyone knows if it is ok when there are only four of the five connectors connected on the back of the fan speed knob?

Jonas

Last edited by JonasBerg; 10-10-2016 at 01:18 PM.
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post #10 of 13 (permalink) Old 10-18-2016, 12:58 PM Thread Starter
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I (finally) removed the heater resistor board. the resistor coils don't look that bad, except of the the two pins that face each other. between those two pins there is/should be a straight wire that should have a resistance value of 0.5 ohms according to another thread. on my board, this wire has a "gap" where it is not connected. In addition the pins are pretty rusty. I will try to clean the pins as good as possible and replace the disconnected wire with a new resistor. However, I'm not sure if I can use a ceramic resistor to replace it.

Does anyone have experience with replacing the resistor coils?
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post #11 of 13 (permalink) Old 10-22-2016, 05:28 PM
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The fan will not work if that straight resistor wire is blown. I've had trouble with those in the past. I replaced it with a piece of solder wire which seemed to work. It will blow if the bearings in the fan are getting dry and tight. They are sintered brass bushes and the oil in them dries up over time. If they are dry, they tighten up after the fan has been running for a while. I think your fan assembly would be the same as ours in Australia, so unfortunately to lubricate those bearings you have to remove the whole dash to get at them. I am trying to work out a way of cutting an access panel so that it is easier to get at if needed in future.

Current Alfas
2010 159 ti 1750 TBI sedan (red).
2004 GT 3.2 V6 (Stromboli Grey).
2008 159 TI Sportwagon 2.4 JTDM (Stromboli Grey).
1987 75 3 litre (red). My first 75 and now my son's.
2000 156 2 litre Twin Spark, ( Cosmos Blu metallic), my daughter's car.
2000 156 Monza Twin Spark, (Cosmos Blue metallic), son’s girlfiend’s car.
1999 GTV 3 litre 24 valve V6, metallic black, (son’s new car).

Non Alfa
1988 Range Rover Classic Highline 3.9 V8

Past Alfas
1989 75 3 litre, written off by runaway van.
1990 75 3 litre Potenziata (black), now sold & living in Newcastle NSW.
1990 75 3 litre Potenziata (grey, sadly deceased due to fire).
1982 GTV 2 litre, red, (daughter's first Alfa)
2 x 1992 164s, (1 red, 1 grey).
2 x 1988 33s, (both red).
1985 GTV 2 litre, (white).
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post #12 of 13 (permalink) Old 10-23-2016, 12:50 AM
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@oz3litre We only tried full throttle with the fan (full 12v) and there was quite some bearing noise - is that normal? Needless to say were a bit reluctant to remove the whole dash...

Learning, learning..
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post #13 of 13 (permalink) Old 10-23-2016, 02:28 AM
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Quote:
Originally Posted by AlessandroM View Post
@oz3litre We only tried full throttle with the fan (full 12v) and there was quite some bearing noise - is that normal? Needless to say were a bit reluctant to remove the whole dash...
All four of mine have been noisy on full speed. They vibrate a bit. The bearings tend to squeal when they are dry and the fan doesn't spin easily by hand. I don't know what they are like if the bearings are well oiled because I have never had the energy to remove the dash just to add a bit of oil to them. If I figure out a way of gaining access without dash removal I will post it on here. Our American friends are better off than us because I believe they can get the fan out from the footwell.

Current Alfas
2010 159 ti 1750 TBI sedan (red).
2004 GT 3.2 V6 (Stromboli Grey).
2008 159 TI Sportwagon 2.4 JTDM (Stromboli Grey).
1987 75 3 litre (red). My first 75 and now my son's.
2000 156 2 litre Twin Spark, ( Cosmos Blu metallic), my daughter's car.
2000 156 Monza Twin Spark, (Cosmos Blue metallic), son’s girlfiend’s car.
1999 GTV 3 litre 24 valve V6, metallic black, (son’s new car).

Non Alfa
1988 Range Rover Classic Highline 3.9 V8

Past Alfas
1989 75 3 litre, written off by runaway van.
1990 75 3 litre Potenziata (black), now sold & living in Newcastle NSW.
1990 75 3 litre Potenziata (grey, sadly deceased due to fire).
1982 GTV 2 litre, red, (daughter's first Alfa)
2 x 1992 164s, (1 red, 1 grey).
2 x 1988 33s, (both red).
1985 GTV 2 litre, (white).
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