Air Bag light comes on intermittently and heat goes on and off intermittently.

What is your question?

I recently had a tune up and the car runs great. No problem with the engine. However, a couple of days ago the air bag light came on and would not go off. I always fasten my seat belt before turning on the ignition. With that, heater is not working either coincidentally. The fan does turn on at all. However, when I turned on the ignition today the air bag light came on then went off which is good, and the heater starter working perfectly. It seems these 2 issues are happening intermittently. Does anyone know what's the problem? Fuses? Sensors?