What are the recommended fan on/off temps? Any suggestions for a '67 Impala with 99 LS1 auto being used for long haul driving? Thanks!!

 

Mine has a 160° T stat and about 190° fan turn on setting.

Fan settings will vary with the T stat temp.

 

180 T-Stat.. with low on at 185 and high at 200, I use a SPAL standalone controller and can adjust it on the fly.

 

Does anyone have the factory specs for the on/off temps for fan 1 and 2? Thanks!!

 

Wow.. that one hasn't been asked in some time.. I can't recall but I think low comes on around 212 and high at 227 ?.. I am should someone will ping in and correct me.

 

This is what the GM service manual says for a 2005 Vette

Cooling fan speed is effected by many different conditions and can be adjusted from 10% to 90% duty cycle (PWM), 90% is considered high speed fan. When multiple cooling fan speed requests are received the ECM uses the highest cooling fan speed of all the requests. The ECM commands the cooling fan ON under the following conditions:

Cooling fan duty cycle starts when engine coolant temperature reaches approximately 95°C (204°F) and reaches high speed at temperatures above 113°C (235°F).
Cooling fan duty cycle starts when A/C pressure reaches approximately 1100 kPa (160 psi) and reaches high speed at A/C pressures above 2480 kPa (360 psi).
At engine oil temperatures above approximately 150°C (302°F) the cooling fan duty cycle will be commanded to high speed.
At transmission oil temperatures above approximately 132°C (270°F) the cooling fan duty cycle will be commanded to high speed.
After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 113°C (235°F) or the A/C pressure is greater than 1720 kPa (249 psi) the cooling fan duty cycle is set to 50%, low speed. If the coolant temperature drops below 110°C (230°F) and the A/C pressure drops below 1660 kPa (241 psi) the fan will shut OFF. The fans will automatically shut OFF after 2 min. regardless of coolant temperature.


And this is for a 2001 F body LS1

LS1
The PCM commands low speed fans on under the following conditions:

Engine coolant temperature exceeds approximately 108°C (226°F).
When A/C is requested and the ambient temperature is greater than 10°C (50°F).
A/C refrigerant pressure exceeds 1482 kPa (215 psi).
After the vehicle is shut off if the engine coolant temperature at key-off is greater than 113°C (235°F) and system voltage is more than 12 volts. The fans will stay on for approximately 150 seconds.
The PCM commands High Speed Fans on under the following conditions:

Engine coolant temperature reaches 112°C (234°F).
A/C refrigerant pressure exceeds 1710 kPa (248 psi).
When certain DTCs set.
Under normal operating conditions with A/C requested, the PCM will command the cooling fans on until vehicle speed exceeds 105 km/h (65 MPH).