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Old 19th November 2019, 17:02   #34
alanaslan
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75 Tourer Automatic conn, 75 Saloon Automatic Conn, The Monograme Spice Tourer

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Quote:
Originally Posted by SD1too View Post
Poor flow through the heater won't cause high coolant temperature Alan.

Dave's fan has two speeds, as he states in the post you've quoted.

Simon


Simon you are quite correct but the control circuit has three, and it can not know what fan is fitted, what happens is the slow and medium speeds become speed 1 and the high speed remains the same. Hence the need for a resistor heat sink on the wiring.
So the three speed protocols still apply.
As to the possible poor water flow you are correct it would not cause a high coolant temp but it could cause the poor heat transfer on the passenger footwell.
The only way to check the possible overheating would be to run the engine and take digital temperatures of the coolant temp.
Then remove the engine thermostat and see what the difference in the graphs are on the same protocols used with the stat in place.
This will allow to determine if the engine is running hot or not or if a sensor is off. You can buy adhesive colour strips in 5 degree and 10 degree increments. These small inexpensive strips are often used in CHP units worldwide and also in motor sport. There great for a reference check.
Hope this info helps any confusion I caused.
Basically the fan runs at two speeds but the car thinks it has three.
Which is one of the reasons we fit heat sink resistors to protect the fan.
Alan



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