[luis77]

My radiator fans switch from low speed to high speed every 5 seconds. If engine is hot enough, they will stay on high speed. If I turn on the A/C, the fans start at low speed and immediately swithch to high speed cycling between low and high every 5 seconds. If I disconnect the thermo-switch, same problem occurs when I turn on the A/C. If I disconnect the a/c pressure switch, or both the pressure switch and radiator thermo-switch and switch on the a/c, still the same problem. If engine is off, still the same problem every 5 seconds until car cools down, and then it stops after 3 mins or so (something it has always done in low speed when system worked properly).





Please help!!!



I am worried this might damage the fans and power lines.



Thanks!



P.S. Resistors and wiring look fine. I am suspecting a bad relay.

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[DaveN]

I'd almost guess low coolant in the rad. Air pocket playing tricks with really hot rad fluid on the thermo switch. Do you have coolant flow?

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[RS Barn]

Is the A/C Compressor cycling also? Too high a head pressure will cause that problem

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[luis77]

Compressor is NOT cycling. It is working fine. Engine temperature is also ok

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[RS Barn]

You need to fly Max to Caracas

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[John]

Luis77, go to the Topic "Electrical Trouble-Shooting the 968 Cooling System" located under Elec. Gauges... in the DIY section,

and download the file "968CoolingSysDiagTests...". There find tests relating to the fan relay and the thermo switch, which may

(or may not) help you determine the fault.

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[tamathumper]

That is one first class DIY document!

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[jg968]

My car exhibited the exact same behavior. I went through the DIY document and it said I had an open circuit. Turned out to be a bad spade connection on one of the resistors. Have you tried cleaning them to make sure you're getting good contact.



Jerry

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[luis77]

Problem solved! Cleaning the contacts on my resistors worked! My fans are working perfectly now! I was about to spend $$$ on a new relay.



Thanks for your help!

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