There is a tiny hole in my 2007 model ford fiesta's coolant expansion tank. I closed it with an epoxy and everything is fine. I drive car and there is no decrease in coolant level, the problem started when i switch ON the AC.
Heater and A/C Problems
Does your air conditioning blow warm? Does the heater stay cold? Is the drivers side dash vent temperature different from the passenger side temperature on A/C or heat? Read these articles.
If the freon charge is good, and the compressor WILL engage and stay on, but the dash vents still blow warm air from all vents, then the air delivery system needs to be checked next.
Depending on the vehicle, there are several doors, actuators and motors that direct the incoming air over the A/C evaporator to cool the air. Any number of problems can cause the air to either be warm, or just a little cool.
The most common thing to cause the A/C system blow warm or cool-not cold air is that the freon charge is low.
Compressed refrigerant from the compressor enters the condenser in a high temperature, high pressure vapor state. As the refrigerant flows through the condenser, the heat of the refrigerant is transferred to the ambient air passing through the condenser.
Drivers Side Blows Cold, Passenger Warm - Or Vise Versa
Most of today's cars and trucks have the ability to blow different air temperatures form the drivers and passenger side. Even if you do not have dual-zone controls, there still may be two separate doors and motors to control the side separately.