Phenomenon: Temperature Gauge needle: 1996 Mustang SVT convertible.

[retiredly]

Folks, using the below baseline, I discovered the heater fan effects the water temperature

Gauge.

BASELINE: Fan knob in low position, temperature setting neutral position, select mode in off position
My vehicle was running and the temperature gauge was midway.

When the select knob is set to a function and the fan speed is increased, the needle for the temperature gauge will increase when a fan speed is selected.
And when the fan speed is decreased the temperature gauge will decrease.

NOTE, the temperature gauge needle does not increase when a select function mode was selected and the fan was in the off/low position.

Any thoughts?

 

[manicmechanic007]

Check all the grounds
Check the cluster ground in particular
I do not have an EVTM for a 96 but the grounds are always in about the same place
I believe you are looking under the left kick panel or below the left side of the dash lower metal brace
Your local library should have AllData where you can access Ford manuals for free
Whenever weird stuff happens it usually boils down to a bad (loose) ground wire

 

[manicmechanic007]

I used to drive cop car mustangs around when I worked at the dealer in the 80's thru the 2000's
We used to play with their radar detectors
You could aim the ray gun at the blower motor and get any speed you wanted