Some times a bad battery or a bad ground can do this.
The instrument cluster is what houses the speedometer, and the gauges.
Analog gauges do not use digital numbers or digital displays. Analog gauges use dials or a pointer. Think hands moving around a dial as in an analog speedometer. If it has digital numbers then it is not an analog gauge it is a digital gauge.
you need a new instrument cluster about $350 same happened to mine.
There is no speedometer cable anymore, it's all electronic.
The power or ground connections to the instrument cluster could be bad. Check the fuses, then the wiring to the dash to find a common problem for the heat, gauges and speedometer.
Nothing
it coulld have a blown fuse wich operates the instrument cluster
Cluster means all the gauges and warning lights on a vehicle i.e. fuel gauge,temp gauge speedometer, odometer, oil pressure warning lights etc.
There are many places where one could purchase digital HVAC gauges. One could check online shops such as Amazon or eBay for deals on digital HVAC gauges.
It's totally fixable. This is pretty common on the 2005 Mustangs, it's caused by failing stepper motors in the instrument cluster, they control the movement of the gauges. There's a guide on how to fix them here - www.2005-mustang-speedometer-problem.com
If striking the dashboard encourages or clears the fault then either a bad earth or bad solder joints on the membrane sheet behind the dials.
Fuel, Temp, and Speedometer