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Trying to diagnose temperature increase in my current hot Florida weather. I suspect a fan problem because whenever moving the temps decrease dramatically. I have read many if not all the threads on this and want to clarify one thing. Do both fans always operate at the same time and at the same speed setting? If so, does this hold true for fan actuation due to a/c compressor being engaged? Thanks, Paul
From the factory service manual: The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph)
Yes, both fans should always run or not run together, at the same speed. I have looked at the wiring diagram and it seems that there are no relay failures which would affect only one fan.
I have had several fan motor failures and also had to have my radiator cleaned a year ago. Not plastic bags or such, just dirt.
[QUOTE=wrmiles;1601983126]Yes, both fans should always run or not run together, at the same speed. I have looked at the wiring diagram and it seems that there are no relay failures which would affect only one fan.
These relays are shown not engergized in the schematic .
If relay 43 does not energize only RH fan will be affected (high speed) , while if relay 44 does not energize only LH will be effect ( high speed )
Also, if Relay 45 fails no low fan speed so both don't run AND no LH high speed and if the closed contact of relay 44 fails there is no low fan speed either.
I have been playing with mine for a week with a few different settings. I have EFI Live, though, so I can edit engagement temperatures at will. Running a factory thermostat temperature I took the car out today at lunch and an the AC while idling as I ate. It never crept over 198 parked in what the outside temp gauge in the nose read as 98 to 100*. Prior to this, it was climbing to 215 or so on oem settings under similar conditions.
Yes, both fans should always run or not run together, at the same speed. I have looked at the wiring diagram and it seems that there are no relay failures which would affect only one fan.
I have had several fan motor failures and also had to have my radiator cleaned a year ago. Not plastic bags or such, just dirt.
What did you replace yours with? Is there a brand/model you recommend? These have not failed yet on my 1998 but it is my paranoia of all things!
Don't know the brand the shop got. The second failure was the same side as the first a year prior. Not sure about warranty, but the shop gave me a pretty fair deal.
Where in the manual can you find this? I just got a copy of Restoration Parts 3 volume manual and I cannot find the theory of operation section which I'm pretty sure GM always published in the factory manuals.
Quick Cooling Fan Question
