J-rivers

it seems my heater is not blowing air. the control display will light up and i can hear the vent open when i turn it on. but after about 5-10 seconds of not blowing air it shuts off and then resets and trys again and again. is this a motor problem or a relay that may be faulty? i parked the car inside to make sure it just wasn't frozen. i hope to take a look at it tommorrow and could use and input. thanks.