What causes heater and AC fan motor to quit working on Chevy blazer?

Answer 1

There are several possible reasons. First check the fuse. If not the fuse, find the fan relay which is on the firewall under the hood next to the blower. Depending on the model year there may be more than one relay there. This is most likely the problem. If only HIGH speed is missing, it is the fan relay. If you have HIGH speed but none of the LOWER speeds, it is most likely the resistor. It could also be the blower switch on the dashboard, but my guess is "the relay".

Before anyone goes on changing any switches or relays check the 5 wire connector next to the fan area by the firewall. Over time the connector gets weak. you will see signs of overheating in the plastic. There is an Orange heavy wire and a Black heavy wire. The other 3 wires will be a lot smaller. Cut the 2 heavy wires on both ends of the plug and splice and reconnect then making sure that they make a good and solid contact. Once you do this, you will find that your High fan speed will be working just fine. It worked for me. Good luck !