Cooling Fans-when should they come on?
10-12-2009, 08:13 PM
#1
Cooling Fans-when should they come on?
I have a 1998 C5: It appears that the passenger side fan comes on only when the AC compressor is on. The drivers side is what I'm not understanding- sometimes comes on when the engine is cold. Can someone tell me when it should come on? What temp? Thanks
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Onthat_Z06 (08-14-2019)
10-12-2009, 11:00 PM
#3
Burning Brakes
I would start from the motors and work back. Both motors seem to work, so maybe one of the relays are shot. Probe the relay sockets and make sure the pcm is trying to energize them, and check that they are actually switching.
10-13-2009, 08:22 PM
#5
Le Mans Master
C5 Cooling Fans Operation
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).
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).
10-14-2009, 12:09 PM
#6
Melting Slicks
Member Since: Dec 2003
Location: pawleys island sc
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C5 Cooling Fans Operation
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).
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).
03-04-2010, 06:57 PM
#8
Interesting that 226 & 235 degrees F are the temps. for low & high fans to start. I just bought a '98 LS1 & seen 221 F with A/C off & thought I had a problem. I suppose this is normal & not to worry. Thanks for great info.
01-01-2017, 04:36 PM
#9
If you have only one fan running then you have a problem that needs to be diagnosed. When the fans run both run at the same time at either high speed or low speed.
With the AC on the fans (both) come on at low speed at 185 degrees. They both go to high speed at 194 degrees.
With NO AC running the fans come on at low speed when the coolant reaches 226 degrees. The both go to high speed at 235 degrees.
When the vehicle speed reaches 35mph the fans go OFF no matter what the coolant temp is. Air flow through the radiator is better with the fans freewheeling than with them running.
Hopefully ByronHunter will post the wiring diagram that can help you troubleshoot what may be happening. There are 3 relays involved in the fan operation. One or more may have failed or the fan that runs only on occassion may be worn out.
With the AC on the fans (both) come on at low speed at 185 degrees. They both go to high speed at 194 degrees.
With NO AC running the fans come on at low speed when the coolant reaches 226 degrees. The both go to high speed at 235 degrees.
When the vehicle speed reaches 35mph the fans go OFF no matter what the coolant temp is. Air flow through the radiator is better with the fans freewheeling than with them running.
Hopefully ByronHunter will post the wiring diagram that can help you troubleshoot what may be happening. There are 3 relays involved in the fan operation. One or more may have failed or the fan that runs only on occassion may be worn out.
04-14-2019, 03:39 PM
#10
Instructor
I installed a lower temperature thermostat and would like them to come on sooner.
Not looking for the expense of a full tune.
04-19-2019, 03:57 PM
#11
Drifting
Most of the hand held tuners allow you to set the temps when the fans kick on.
I know the Diablosports do, along with a lot of other handy things, including the ability to buy and load canned tunes from professional tuners.
I know the Diablosports do, along with a lot of other handy things, including the ability to buy and load canned tunes from professional tuners.
