Turn on my heater or AC and my temp gauge goes up?

[1986LX2002]

Ok this is really weird, I turn on my heater or just turn on the fan to blow some air to me. And while driving i just watch my Temp gauge almost peg to H. But as soon as i turn off the fan the gauge goes back all the way back down to Normal. This is pissing me off i thought i fixed all the electrical problems on this freaking car. Oil pressure gauge always pegs too, i'm guessing maybe the voltage regulator? Any other suggestions? My alternator is the stock one and is making this whirrling noise lately so this may have something to do with it. When it comes to electrical i'm kinda lost.

 

[UMDSmith]

The electrical and cooling systems aren't really related. Try using a 2nd temp gauge not routed into your dash instruments to see if when you turn on the blower your temps are really pegging or if it is just the gauge. I don't see why turning on your heater would make temps rise, as it runs coolant through the heater core which is in essence a mini radiator. Check your coolant level as well (simple yet a possible issue)

Juding from the fact that oil pressure and temp gauges are pegging, it sounds electrical. Either that or you have a lot of issues.

Probably a simple voltmeter would be able to tell you if you have issues, but I'll let someone with more experience then I give that information.

 

[1986LX2002]

Yah I know it doesnt make sense to turn on the heater and have the temp gauge go up, that why i'm wondering wtf is going on lol. I need to just buy some actual gauges like some auto meters or something and slap them in. One thing ford really jacked up on is putting in those dumbass gauges. I'm seriously thinking its a regulator i was talking to my friend and said that's the classic sign of one that's bad or on its way out. Now question is where is the voltage regulator? My friend currently has my mustang manual which i need to get back.

 

[HISSIN50]

reg is behind the instrument cluster. dont forget to check for an insufficient ground.
or dont bother and get the real gauges, as you said. very worth the $$.

good luck.