97 heater problem

The heater on my blazer has been acting up lately. Sometimes it will come on sometimes it won't. Up until now I was able to get it to work by turning off the engine and waiting for a minute or two the starting it back up. The last time I tried this the heater still did not work. Any ideas?

Blower motor relay,
Blower motor,
Fan switch bad,
Bad ground to the blower...
Post us back with your findings.......good luck

Where might the relay be located?