93-95 GM 3.4 PCM fan temperature values

[limey222]

Can anyone confirm that the stock PCM for these years sends a command to turn the fan on at 223 degrees F and back off at 185 degrees F?
I am reading this out of the 1994 GM factory Service manual (book 2 0f 2), am I interpreting this correctly?

[Scott Costanzo]

Michael,

If you're using the PCM to control the fan it's an easy thing to confirm yourself with an infrared gun. The PCM takes feedback from the coolant temperature sensor and the GM CTS isn't known for being real accurate. Probably not a bad idea to check just so you'll know.

[limey222]

Well i purchase an infrared gun and I wasn't far off.  The electric fan definitely turns off around 185 F.   The top limit for turning on was a bit sketchy, seems to be around 220 F even though the temp gage was reading around 225-230 F.  Evans waterless coolant boils around 350+ F so the only concern would be oil temperature since I don't have an oil cooler installed.

[MGBV8]

O course, that gun is only reading surface temps. Also, the the readings will be off based on what it is pointed at because of emissivity. Doesn't work as well on shiny objects.  You can add a spot of flat black paint that can be cleaned off later.