Alfa Romeo Forum banner

1 - 5 of 5 Posts
L

·
Guest
Joined
·
0 Posts
Discussion Starter #1
Hi,

My father in law has a 155 TS 1995. The heater fan packed up working. I checked the motor by giving it 12V (OK), checked the resistor pack with a DVM (OK) Checked the operation of the switch with a DVM (OK) and checked security of all cabling (OK). The fuse is OK and the Brown wire on the fan is showing +12V with the ignition on. My question is, where does the orange wire go to that is on the other side of the fan motor. Orange doesn't appear anywhere else on the heater fan circuit and it seems to dissapear somewhere up into the instrument cluster. I don't have a circuit diagram so I am only guessing when I say that the motor is fed with a +12V on the brown wire then the fan speed is regulated by switching various resistor values into the negative. Is that right? or better still, does anyone have or know where I can get a copy of a wiring diagram from. My father in Law loves his Alfa but, if my experience of italian motorcycles are anything to go by, a wiring diagram is a must......or am I being a little unfair ;-)
 
W

·
Guest
Joined
·
0 Posts
Discussion Starter #2
Does it have air conditioning or a manual heater?

wrinx
 
M

·
Guest
Joined
·
0 Posts
Discussion Starter #4
Hi
The orange is the 12v feed from a relay that should power the rear windows & radio via a 30A fuse. The brown wire goes to the fan speed control knob. From there 4 wires go to the rheostat- 1 green, 1 grey, 1 red and 1 black.
The black one also goes to earth and all of the rheostat circuits come back through the black and hence to earth.
Therefore you should have 12V on the orange.
I would suspect the connections/or the rheostat.
As a safety device the rheostat has a thermometric device which deactivates the fan if the temp reaches 90degC.
Hope this helps
 
F

·
Guest
Joined
·
0 Posts
Discussion Starter #5
The Heater resistor pack, the green think under the dashboard, has a thermal cutout, if this is open circuit the 3 reduced speeds will not work, position 4 (?) will still work.
The thermal sensor is spotwelded in , because it gets hot in there, looks like a silver diode. If tested with a multimeter it should read 0 Ohms, if it reads high Ohms or O/L its buggered. They are in the RS catalogue, i just got one to replace mine, 172 Deg C cutout, 10Amp. Part No. 176 9312. The trick is to crimp the new device in on to the old leads without pullling the spotweld off
 
1 - 5 of 5 Posts
Top