Alfa Romeo 159 cooling fan control module test

Later produced models don't have the 2 speed control circuit with 2 relays, so you can not test it with MES (it simply won't start). Here is the way, that I found out to test if your fan control module works properly. I disconnected the water temp. sensor. Connected a 1Kohm (500 ohm is enough) potentiometer to the two terminals. I started around 280 ohm (this is the resistance of the sensor around 90°C). As I turn down the potmeter (lowered the resistance) the ECU thinks that the water temp is rising. Around 100°C the fan starts to work with moderate speed, and above 110°C it starts to spin pretty fast.

[@davidBarrel]

I just test my 2.2jts engine idling 800rpm
TEST 1) aircon ON , temp reaches 90degrees, radiator fan starts bringing down to 87degrees.
TEST 2) aircon OFF, temp reaches 93degress, radiator fan doesn't start.
any ideas why sensor and fan working fine and the fan doesn't receive the signal to start?

[@RubTdi]

Anyone has pinout of this fan module? Its made by Johnson-Gate. It has think power and ground and then a red and green cable which I guess need pwm or so?

[@shomysss]

Does fan starting immediately when AC turn on?

[@pettysct]

I don't think it does.

[@shomysss]

@@pettysct thanks. My fan start on slowly on 99° but when I turn on AC he don't start immediately

[@muhammadfauzi1625]

hi nice work, i had a problem with my alfa 159 jts 2.2. the rad fan only works when ac is on? could you help thanks in advance

[@pettysct]

Thanks! No, the fan should work too, when engine coolant temperature is rising above 100 celsius degrees. In this video my AC is off.

[@mattjacomos2795]

I have the same problem, did you have any success in sorting it out? I have the 2.2 as well.

[@davidBarrel]

@@mattjacomos2795 Hi, did you solved it? I've never hear my fan turning unless the AC is on...anyway the temp never raise above 90deg. according to dash

[@mattjacomos2795]

@@davidBarrel that fan has FIVE speeds and draws a LOT of current. The fan is switched by computer, and the WHOLE system is tied together with the ignition and on board computers as a network. The car will overheat at 100kmh without the fan too, the oil temp is more accurate than the water temp as to what's actually happening inside the engine. basically if the car overheats I'd try disconnecting and reconnecting joiners, as well as checking that the earths are clean. If that does not solve the problem then the computer has failed and the car is basically a throw away (unless you score a write off from the auctions and it HAS to be the same year and model and engine)... Very hard to work out a way to bypass these computers, but a helluva good looking car

[@davidBarrel]

@@mattjacomos2795 I'll try to make a simulation on MES then, I'll check temp and stuff to know if its ok. thank you. Throw away is not an option , cars are very expensive here in Uruguay, this one is 18.000 20.000 U$S

[@shomysss]

Potentiometer from Max to min?

[@pettysct]

No, you only turn it down until the temp gauge goes above 110°C

[@shomysss]

@@pettysct but my start position is Max on potentiometers?