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Temperature of water in engine

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These temps are all dependent upon the outside temps

The fans have 2 modes of operation AC OFF and AC ON.   You will notice that with the AC on, you will see less 'swings' or extremes in coolant temperature

Highway temps should range between 195 and 205

Local driving in the summer will run 212 to 217, traffic bumper to bumper in the summer will run 217 to 235 depending upon the outside temps

Here is info from the Factory Service Manual on the cooling fan operation. When the AC is on, the fans are commanded to LOW speed operation, with the AC off, the fans are off until the temp reaches 229, when the temp drops to 216 the fans will go off (unless the AC is on)... The fans do not kick into high speed operation till 234

The PCM will command fan operation when:


  • Low Speed Fan Operation
    • Engine coolant temperature exceeds approximately 106°C (229°F).
    • Transmission fluid temperature exceeds 150°C (302°F).
    • A/C operation is requested.
    • After the vehicle is shut OFF if the coolant temperature at key-off is more than 151°C (304°F) and system voltage was more than 12 volts. The fans will stay ON for approximately 3 minutes.


The fans will switch from low to OFF when the coolant drops below 102°C (216°F).


  • High Speed Fan Operation
    • Engine coolant temperature reaches 112°C (234°F).
    • Transmission temperature is more than 151°C (304°F).
    • When certain DTCs set.


The fans will switch from high to low (except DTCs set) when the coolant drops below 106°C (229°F).

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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