Blower motor on AC only works on two of four speeds so I ordered a blower motor relay from The Parts Place. Thought I was getting the unit that fits inside heater box. When I opened the package there was a relay that fits on the exterior of the box or firewall?. Did I order the wrong part or are there different relays used for the same application

 

The blower motor relay is a relay (an electric switch) that bolts to the firewall and only provides power to the blower motor on HIGH speed. The thing in the HVAC box is the resistor that lowers voltage on the other speeds to slow the motor down.

 

Thx Mr P ! I'll replace the relay in hand first since I have power to the lower two speeds and none at high. Then see where I am. I am nearly done with the car after three plus long years. Will post pics soon