Likely, your blower (fan) is out.
Sounds like there is a damper closed somewhere.
Try checking the fuze located underneath the panel which you remove to replace the batteries. Put new batteries in, a new fuze and don't forget to cut off the circuit breaker before doing all this. I did and I now have warm/hot air coming through my vents!
By conduction, convection and radiation.
In The Basment
Heat energy leaves the house due to convection, conduction, and radiation. Convection occurs when warm air rises and is replaced by cooler air, carrying heat energy out. Conduction transfers heat through direct contact with colder objects like windows and walls. Lastly, radiation allows heat energy to escape as infrared radiation through windows and gaps in insulation.
the heat blows out the defrost when it should blow out floor vents only
Because the air selector died.
you need a head casket
Because most likely there is still coolant circulating through the system.
Having the ceiling fan blow upwards will circulate the heat through the entire room.
somtimes a mouse moves into the blower motor and makes a nest ?
Yes. The heater core provides the heat which blows out your vents. The heater core has engine coolant flowing through it (it is like a mini radiator) which creates the heat which warms the air that comes out your vents. If you have low coolant, there may be no coolant circulating through heater core, thus causing cold air to blow out vents.
perhaps because the engine running heats coolant that cycles through the heater core and has air blowing across the aluminum to exchange the heat into the air that is forced through the vents
More than likely you will not have heat being the water wont be circulating through the heater core , When the hot water passes through the heater coil the air passing through the heater coil makes heat blow out the vents when you have selected a heat setting on your controls.
Fuel level, heat or air conditioning up, both high and low, high only, floor only. Center vents are for air conditioning output only, no heat. Heat is designed to blow out side and floor vents only. NOT center. Center is only for air conditioning or summer vents.
You dig hole in living room floor and wait for magma to come out. Then house is br00tally warm.
some thing is probley cloging the vents take it appart and ckeck.