Temp Gauge varied with 'fan speed'????

[Flye]

Since I replaced water pump, belts, hoses, thermo I've had a 'pulsing' temp gauge. After reading posts here, I replaced cap, both sending units, and another thermo. Same problem. I learned to ignore it.

NOW, TODAY.........

I looked down and the temp gauge was almost pegged, but motor was running fine. I watched briefly, then turned A/C off. Not only did gauge drop to 'normal', it dropped IMMEDIATELY.... I knew A/C could not have truly affected temperature that quickly.

I then started experimenting with fan switch. I figured out I could make TEMP gauge go up and down by FAN SPEED, regardless if it was simply on vent or A/C (no difference between the two).

After my next stop and restart, it was 'fine', and I had no issue with temp gauge regardless if fan was on or off.

Does dash have a separate voltage regulator?

ANY STARTING POINTS? This one was weird enough to post for input.... Thanks,

 

[ezrider440]

hey buddy
i honestly couldn't tell you becaue i struggle from the same issue, i do not know what motor you're running but i have the 5.0l and the temp guage jumps up and down not noticable but pulsing like, i don't know i've checked my temp with a laser type thermometer and it's constant so maybe it's a dashboard problem?

 

[Flye]

It is 6 cyl

Explorer is a 6 cylinder.

Question for you: Did you replace water pump on yours yet? It seemed several people had the problem after they replaced water pump. This is exactly when the pulsing of temp needle started.

The temp needle being affected by fan speed has only happened once and hasn't come back.

Thanks,