Since its gotten cold out I was going to use my heater the other day. I turned on the heater and The blower fan blows air out of the vents but no heat on any of the vent settings. Not even defrost. The coolant reservoir is full so its not because of low coolant level. This is the first winter I have driven this car so I have no idea if it worked last year. The A/C does not blow cold either. Not sure if the two are related. Please help, Its cold out!