Engine warning light say "engine over heating" and heater blows only cold air and the vehicle looses speed

SOURCE: Faulty Fan Heater - The main vents are just blowing out cold air.

all cars have a recycled air weather its called max or just recycle its doing the same thing. So if your getting cold air in one spot and hot in another it means your vents are not blocking where they are suposed to. It could be just a simple fix, by getting into the dash where your vent controls are and looking at the flap that tells air where it can and cant go. if its stuck then it needs to be cleaned and oiled. If the cable is corrodend clean it and oil it so it can move freely, or just reconnecting it may be the fix. it sounds like you are going to have to be adventurous, and play with the mechanics of your vents. Typicaly theres really nothing tough there to work on, just REMEMBER WHEERE ALL THE SCROOS AND CLIPS GO. I have forgotten where a few went in the past and had to listen to sqeaking noises till I took it apart again. There are vent seals wich are no more than the weather stripping you buy at the hardware store the 1/8 inch thick tape. You may need to thin it down with a razor, usually not. but it works great for fixing the seals in car heaters, because its the same thng just a different color. Which no one will ever see.

SOURCE: 1998 BMW 328i heater/AC blower is not running

You have clean the blower unit , may be its dirty then . and then check the blower resistor unit for malfunction.

SOURCE: my 2003 325i blows cold air, heater never heats

Potential causes: Low coolant- fix by adding coolant Thermostat stuck closed- would also cause engine to overheat Thermostat stuck open- would eventually blow at least luke warm air Heater core plugged- Get it backflushed or replace it These are the most common causes