intermittent temp malfunction

The heating and airconditioner stops working. E comes up as outside temp. Then the heat and cold does not work. This happens intermittently and then nothing works for both air conditioner, heat, no air flow not change in vents. How to I diagnose what is wrong?

 

I've had that same thing happen a few times. It's so intermittent I forget all about it until it happens again

 

Check the connector on the resistor pack down by the blower motor also check the connector at the motor. They may be burned due to a loose connection. Common problem.

There are two down by the blower motor under the passenger side dash ( behind the glove box).

One goes to the resistor and has 4 wires. The other goes to the actual blower motor and has only 2 wires.

Resistor image:



Blower motor connector: