Heater blower motor

[/6Volare]

Hi guys.
I'm having an issue with the blower motor in my son's 77 volare working intermittently. When it works its great but it will stop working without reason. I changed the switch yesterday and it seemed to solve the issue until this afternoon. The fan makes no unusual noise. Hard to resolve when its random. Irs a pretty simple system.
Any thoughts?
Jeff

 

[80mirada]

Loose ground, corroded connectors, thermal resistor failing, or a bad spot in the motor contacts/ bad brushes

 

[/6Volare]

Contacts all seem good. Havnt found any loose wires.
Possible that the motor works intermittently from faulty / aged winding? How difficult is it to remove heater box to change out the fan?

 

[BudW]

What 80Mirada said pretty much sums it up:

Loose ground, corroded connectors, thermal resistor failing, or a bad spot in the motor contacts/bad brushes

The switch might be the most likely cause – but you said you already changed that.
The other “main” components of that system is the blower resistor and blower motor.

The blower resistor usually is either good or bad – and not intermittent.

The wiring harness (including connectors/connections and ground connection) and blower motor can be intermittent.

You didn’t mention what year car or with or without A/C – so instructions to getting to the blower motor can be properly given.
BudW

 

[Aspen500]

If not done already, look at the resistor connector and be sure there isn't a melted terminal. I've seen that before and it can cause sporadic fan operation.