Technical Cooling Fan issue

[barrage54]

Hello. Im having a bit of an issue. My cooling fan will not engage. I also needed to do the water pump so I went ahead and did all the Cooling components. New Fan Switch sensor. Both temp sensors on the engine, new hoses, thermostat and I added the high point coolant filler connector to the High point on the Heater hose. The car reaches temp and there is no air in the system. Problem is the Fan will still not engage once they temp is reached. If im driving the temp stays in range. If I stop or am in traffic it will creep up slowly but I never let it get too hot. I replaced the Fan Sensor twice just in case the first one came in faulty but still no fan. If I touch the 2 wires of the fan and set the ground the Fan works. Any suggests. Only thing I have left is run a switch to manually engage the fan.

Thanks in Advance
Alex

 

[bugsymike]

Hello. Im having a bit of an issue. My cooling fan will not engage. I also needed to do the water pump so I went ahead and did all the Cooling components. New Fan Switch sensor. Both temp sensors on the engine, new hoses, thermostat and I added the high point coolant filler connector to the High point on the Heater hose. The car reaches temp and there is no air in the system. Problem is the Fan will still not engage once they temp is reached. If im driving the temp stays in range. If I stop or am in traffic it will creep up slowly but I never let it get too hot. I replaced the Fan Sensor twice just in case the first one came in faulty but still no fan. If I touch the 2 wires of the fan and set the ground the Fan works. Any suggests. Only thing I have left is run a switch to manually engage the fan.

Thanks in Advance
Alex

Can you test the sensor in a pan of water using a good thermometer and wires to a meter to see when it actually cuts in. Some sensors have the temp. written on them. Cars run more efficiently when nearer 100 degrees Centigrade /212 Fahrenheit , a lot of cars run thermostats these days set in the 90s Centigrade, the temperature doesn't damage the engine as long as the pressurised cooling system is functioning correctly. For every 1lb of pressure the water will boil at 1.5 degrees Centigrade higher, so a 10lb cap will let the water boil at 115 degrees Centigrade, which is why a mountaineer has a job to make a decent cup of tea .
If the pressurised radiator cap is opened on a hot engine the water boils instantly causing damage, as steam can reach a much higher temperature being a gas, than the water as a liquid, warping cylinder heads and blowing gaskets etc. Hence things like "superheated steam".
Years ago a customer wanted an electric Kenlowe after market fan fitted to his new car, in those days the fan was fixed solid to the water pump not even able to freewheel via a viscous coupling, after removing his old fan the only way we could get his car hot enough to reach the fan cut point was by blanking off nearly all the radiator.
If you are not happy and want it to cut in earlier you can buy from Kenlowe or similar a switch that can give you the option of both a lower cut in point set by you , but also the ability to over ride it if needed. They supply to people who use their cars for competition events as well as everyday drive to work etc.
Sorry if I babble on , I tend to over explain things according to my daughters, but at 70 unlikely to change.

 

[barrage54]

Can you test the sensor in a pan of water using a good thermometer and wires to a meter to see when it actually cuts in. Some sensors have the temp. written on them. Cars run more efficiently when nearer 100 degrees Centigrade /212 Fahrenheit , a lot of cars run thermostats these days set in the 90s Centigrade, the temperature doesn't damage the engine as long as the pressurised cooling system is functioning correctly. For every 1lb of pressure the water will boil at 1.5 degrees Centigrade higher, so a 10lb cap will let the water boil at 115 degrees Centigrade, which is why a mountaineer has a job to make a decent cup of tea .
If the pressurised radiator cap is opened on a hot engine the water boils instantly causing damage, as steam can reach a much higher temperature being a gas, than the water as a liquid, warping cylinder heads and blowing gaskets etc. Hence things like "superheated steam".
Years ago a customer wanted an electric Kenlowe after market fan fitted to his new car, in those days the fan was fixed solid to the water pump not even able to freewheel via a viscous coupling, after removing his old fan the only way we could get his car hot enough to reach the fan cut point was by blanking off nearly all the radiator.
If you are not happy and want it to cut in earlier you can buy from Kenlowe or similar a switch that can give you the option of both a lower cut in point set by you , but also the ability to over ride it if needed. They supply to people who use their cars for competition events as well as everyday drive to work etc.
Sorry if I babble on , I tend to over explain things according to my daughters, but at 70 unlikely to change.

Youre Not babbling. Great Information ! Thank you

 

[s130]

I would suggest you check the 124s electrical circuit diagrams. Fiat cars of that era just had a fan temperature sensor/switch on the side of the main radiator. Is this one of the sensors your changed?

+BAT------[Ignition Switch]--------[Radiator Sensor]-------[Fan]---------EARTH

or

+BAT--------------------------------[Radiator Sensor]-------[Fan]---------EARTH

 

[barrage54]

I would suggest you check the 124s electrical circuit diagrams. Fiat cars of that era just had a fan temperature sensor/switch on the side of the main radiator. Is this one of the sensors your changed?

+BAT------[Ignition Switch]--------[Radiator Sensor]-------[Fan]---------EARTH

or

+BAT--------------------------------[Radiator Sensor]-------[Fan]---------EARTH

Hello

Yes that is 1 of three I switched. The current wiring on the Fan switch in the radiator is +BAT--------------------------------[Radiator Sensor]-------[Fan]---------EARTH

Ive switched out every cooling component in the system except them Fan but if you ground fan switch the fan turns on. Its very strange.

 

[124BC1]

I did as 's130' suggested and checked out a 124 Spider electrical wiring diagram.

There's also a relay in the engine cooling fan circuit.
This, iirc, should be located on the driver side inner fender - I'm not sure which one it is but the cable colors going to it and the associated relay terminal no's are :- Blue- 87, white/black- 86, white- 85 and violet- 30/51.
Because of the inclusion of this relay, the way the fan is switched is a little different to what you might have been thinking.

In short, when the engine get too hot, the radiator switch provides a ground to the relay (white/black cable@terminal 86) which then closes and supplies power (via terminal 87, blue cable) to the fan (blue cable). In other words, the fan is switched on by the relay supplying it with a live feed via the blue cable.
The other cable (black) on the fan motor is always grounded.

The remaining 2 cables on the relay, violet,terminal 30/51 is a live feed from the fusebox; white, terminal 85 is a live feed to the operating coil in the relay.

The usual way of checking out the radiator fan switch is to join the 2 wires (both are white/black) together - if the fan then runs (iirc the ignition needs to be turned on?) the rad. fan switch is faulty. Alternatively, it can be removed and placed in boiling water to check for continuity across the 2 terminals, as described above by' bugsymike'.

The fact that you can get the fan to operate (I'm not sure what you mean by 'touch the 2 wires of the fan and set the ground?), suggests that the fan, fuse, most of the wiring and probably the relay are o.k.

So, what to check? There are 2 wires going to the rad. switch, both are white/black.
One of the white/black wires goes back to the relay (terminal 86). If this wire or terminal is grounded and the fan works, then this wire is ok, also the relay is ok.
The other white/black wire should be grounded, this white/black wire appears (on the circuit wiring diagram that I have) to be connected to the black wire going to the fan motor, both of which which get their ground at the *alternator voltage control box* (large black box on l.h. inner fender) mounting. I would suggest you examine this wire and it's ground.... Also check for ground continuity on the black wire going to the fan - this should also be grounded at the voltage regulator mounting. The simplest solution might be to simply connect both of these wires to a new ground point.

(*I don't know which year your car is, if it's later than my wiring diagram, it's possible that the alternator has a built-in voltage regulator, in which case there won't be a large black voltage regulator box on the inner fender,* but I'm doing the best that I can with the info available to me).

The 2 temperature sensors on the cylinder head have afaik nothing to do with the operation of the engine cooling fan - one is for the coolant temp. gauge, the other is for the high coolant temperature (aka engine overheating) warning light.

Hth.

 

[124BC1]

^^ I was trying to edit the above but ran out of time.

What I'm suggesting is:-

There are 2 white/black wires going to the rad. fan switch.
One of these should be grounded at all times.
The other provides a ground to operate the fan relay.
To check which white/black wire is which, the one which when grounded causes the fan to run is the ground wire for the relay, the other should be the ground.
Simplest solution:- If grounding one wire causes the fan to run, then connect this wire to one of the rad switch terminals, Connect the other switch terminal to ground using a new wire.

Hth.