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Jim Kanomata
Applied/GMC, Newark,CA
ji...@appliedairfilters.com
http://www.gmcrvparts.com
1-800-752-7502
Jim,
Let me try to work that switch for you. I did work in the cooling group at Jeep for a couple of years.
The reason for the thermostatic clutch on the fan being controlled by radiator temperature is a very simple explanation. It was the least cost
method. As a supplier that got beat up by buyers for a one penny per piece price increase, I can affirm that they are that sincere.
Next, why the thermostatic fan clutch at all? One "word" -
CAFE (Corporate Average Fuel Economy)
A typical engine driven fan pulls a lot (~2~4Hp) depending on speed. The power drain is the CUBE of the speed. A bare engine without a fan will turn
in much better performance values.
Lots of smaller cars had electric cooling fans years ago. Yes, and most were trans-verse engine so a engine driven would be impractical. That pried
the door open.
Then, came along the ECU/C (Engine Control Unit/Computer). As these soon got to the stage where they were observing all the engine's conditions,
adding a coolant temperature switch was only adding a couple of lines of code to book the size of a city phone book and another pass transistor on the
heat sink. When engine power went up, the fan power had to increase too, so an number of vehicles had to have a fan control module to handle the
load.
Then they could loose the **** thermal clutch and the associated calibration issues and warranty. And as an added benefit, not having the fan on the
waterpump shaft reduces the load on those bearing and with it off the FEAD (Front Engine Accessory Drive) reduces the load that those components have
to address.
Now, I going to intentionally muddy the water just a little...
When running test engines for a client, they were always run with a regulated coolant out temperature because that is what the client specified.
When running a development engine for our own use, we would control the temperature of the coolant in and monitor the coolant out just as a
reference.
When I can finally do the study, I am going to change the control on my fan clutch to water in and let the thermostat be the control on water out.
If there is a question there that I did not answer, please ask away.
Matt
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Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
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