Fan Problem

[Road Snake]

Just wondering if it normal for the fan to Jump on and off about every 20 seeconds or so? and also does the fan stay on with air conditioning operating, or depending on the temprature of the engine. replaced Temp guage sending unit a couple of weeks back, because it stopped working. The Fan seems to turn on and off even before 200* degrees! Do I have another sensor gone bad? I own a 98 R/T 10.

 

[Tom F&L GoR]

It seems a little odd that it turns on and off that fast, but possible. The fans turns on at 209F and off at 204F.

The fan should come on and stay on with the AC on, in fact, it should run at high speed whenever the AC is on. The fan should come on even if the coolant temperature is below 204F, if the AC is turned on.

The idiot light, the gauge, and the PCM all use different temperature sensors. The PCM controls the fan, and it also knows when you've turned on the AC. (a little "Hal".) A bad gauge sensor has no effect on the PCM or fan operation.

A little news to those with 180F thermostats - on my Gen 1 the PCM temp is lower than gauge. So while your gauge is lowered with the theromostat, your coolant is even lower. Not that good for the oil.