tboneportly
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| posted on 4/6/09 at 01:05 PM |
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sierra 2.0 DOHC radiator fan wiring
hiya
trying to work out why my rad fan isn't coming on
I have the carb version of the Ford 2.0 DOHC - approx 1990, with a basic engine management system
there is a sensor on the thermostat housing (or thereabouts) which has 4 wires:
2 x black - joined together and connected to what I think is the E/M module power relay
Black/Red - goes to the fan connection block, but no further
Black/Blue goes to the fan.
The fan has a seperate earth
I'm guessing that the power comes from the relay and the sensor switches it through to the fan - is that right?
any clues as to how I can test it please?
cheers
Terry
 
Rescued attachment rad_fan_wiring.jpg
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r1_pete
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| posted on 4/6/09 at 02:31 PM |
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As standard the dohc sierra had two fans, it was very susceptable to head warpage and cracking through heat. The wire you show as not connected is for
the second fan.
The two blacks should be live when the ignition is on, if they are not thats where your fault lies.
[Edited on 4/6/09 by r1_pete]
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deezee
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| posted on 4/6/09 at 02:41 PM |
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Surely the Thermostat should run across the input on the relay, and the fan connected direct to the output relay. After all, thats how a relay
works.
Its seems your way has all the load going through the thermostat to supply the fan. I make no claims to being an electrical expert, but thats not how
I'd wire it.
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dinosaurjuice
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| posted on 4/6/09 at 03:09 PM |
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quote:
Originally posted by deezee
Surely the Thermostat should run across the input on the relay, and the fan connected direct to the output relay. After all, thats how a relay
works.
Its seems your way has all the load going through the thermostat to supply the fan. I make no claims to being an electrical expert, but thats not how
I'd wire it.
i have to agree, fans can draw a lot of current on startup.
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sprouts-car
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| posted on 4/6/09 at 03:22 PM |
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I thought there should be a relay too, but asked at got this:
Linky
HTH
Chris
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t16turbotone
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| posted on 4/6/09 at 04:27 PM |
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R1 pete is correct, the thermostat has 2 poles (switches) inside, one set to close at 85 degrees the other about 90 degrees. i.e two stage, you need
12v on blacks (relay energized) and then as temp rises thermostat contacts close
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tboneportly
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| posted on 5/6/09 at 11:57 AM |
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ta very much!
I had my suspiscions about 2 fans, but mine runs really cool - hardly used to get above cold on the original ford temp gauge, and the fan very rarely
came on. I'll assume it's working for now and do a bit of testing after the MoT this afternoon.
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tboneportly
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| posted on 10/6/09 at 08:08 PM |
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can I wire in a manual switch (in case of emergencies) like this:
wire from black to switch
wire from fan to switch
so basically I bypass the fan sensor if I need to turn it on manually
cheers!
 
Rescued attachment rad_fan_wiring_with_switch.jpg
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