cooling fan operation

Topcat

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First of all hi to all , been away a long time .
I have been super busy but I hope to have more time now that the summer is upon us..
My 96 Mark VIII has been giving me some trouble
Can someone explain the operation of the cooling fan ? Does it ever shut off when the engine is running and up to temp? If so at what temp does it come on and what temp does it go off... Doesnt it have 2 speeds ?
 
RE: cooling fan operation

According to the BOOK (my car, not yours):

If high side pressure is <150psi, RPM of motor = 1000
As pressure increases up, the Control increases RPM
At 295psi, fan speed is 1800 RPM
If high side reaches 425psi, AC compressor stops, but fan still runs
at 200 psi, compressor is allowed to operate.

The fan is turned off at speed > 47 MPH.
Fan turns back on when speed drops to about 42MPH

I did not see any reference to actual water temperature/fan operation.
 
RE: cooling fan operation

I suspected as much with the AC..The speed info, 47 and 42, is interesting ...Here is the problem I just siezed my cooling fan motor on the road and had it replaced ,you dont even want to know how much !! Anyway the mechanic said to me the fan never shuts off after the car is warm , and that might have been the cause of the failure, .I dont know if its on when you first start the car in the AM..I wont know till the morning..if it is maybe the relay is welded together from the motor burning up...With the car idling in my drive and the engine at its normal position on the guage , and the AC off the fan does not go off ..Thus this post ... Any further info would be appreciated ..
Thanks Jerry for the info you supplied
 
RE: cooling fan operation

I remember testing my '93. With the AC off, the fan would turn on at 215* and back off at 205* when it was stock.
 
RE: cooling fan operation

[div class="dcquote"][strong]Quote[/strong]
I remember testing my '93. With the AC off, the fan would turn on at 215* and back off at 205* when it was stock.
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Hi John
Been a long time , I remember when you were doing the whole thermostat thing ...I have a "chip in my car also" its not stock either ...What is your fan doing now ? Mine will probably work the same way..I didnt think of the reprogramming, but I guess "they" might have changed the on /off temps for the fan...If those temps are right then my fan is stuck on...
 
RE: cooling fan operation

I haven't actually tested it, but I know I requested lower fan set points on the switch chip.
 
RE: cooling fan operation

Sorry guys I didnt get back to you after you all were so helpful.My job is taking way to much of my time these days , The Fan is working correctly , and does come on and off as expected...So I am a happy camper , thanks again for your help.. I will try to get on on this weekend to say hi to all..
 
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