Cooling fan operation question

[zul8tr]

Some base info

I have a 98 I30 auto and the cooling system is in top shape. New OEM thermostat installed and checked on stove to verify correct open temp and amount of valve opening. No overheating issues both fans operate at low and high speed. Fluid changed each 18 months. All check temps measured with an infrared gun.

Per the FSM generally:

(1)With AC off Elec cooling fans will operate in low speed if coolant > 203 degrees F and in high speed > 230 F (I think 230 correct)

(2)With AC on the low speed fan is always on (<50mph) and high speed will come on for coolant >203 degrees F.

Questions:

(1) Is the temp signal provided for the 2 cooling fans operation from the coolant temp sensor?

(2) With AC on the cooling fans go into high speed with coolant temps at the coolant temp sensor < 203 degrees F and at the thermostat location about 178 degrees F. What can be defective with this high speed fan operation coming on with temps < 203 F? Is it a defective relay? What else can I check?

[MaximA32]

There is nothing strange about the high speed fan operation with the A/C turned on. All vehicle's fans operate at high speed when the A/C is in operation. The vehicle needs cool air to keep the condensor at operating temperature. As I said, nothing strange going on there.

[zul8tr]

I realize that but the high speed fan setting should not come on when coolant temp is below 203F per the service manual and I have mine coming on with temps below 203F. That was what I was questioning. Please see my questions again.

Thanks

[MaximA32]

I need to know if you have automatic or manual temperature controls in order to look in the correct area of the FSM. Also, you're 100% sure that the fan is operating at the high speed setting? Could it possibly be the lower setting and your ears are playing tricks on you? Also, you have to understand how difficult it is to diagnose problems over the internet without the car being in front of you.

[zul8tr]

Car has Auto temp controls, the fan is definatly in high mode because when car warmed up and the AC off the fan rpm reduces to low (very quite) and sometimes no fan is on. When AC put on there is an immediate increase in fan rpm and not so quiet. I have checked the coolant temp sensor at 2 different temps (about 170 and 130F) and the Ohm readings agree with the spec (I actually used a graph in the Haynes manual for the Maxima/Infiniti which agreed with some values I found in the FSM).

I realize that it is hard to diagnose over the I NET so I will provide whatever info you want that I can obtain.

Thanks