Method for monitoring the refrigerant level in an air conditioner

A method for monitoring the refrigerant level in an air conditioner, with a compressor which subdivides the refrigerant circuit into a high-pressure side and a low-pressure side, having the following steps:

• measuring a pressure and a temperature on the high-pressure side at predetermined time intervals;
• determining an assigned temperature using the measured pressure with the aid of a refrigerant-specific function;
• and
• determining a refrigerant undercooling value which can be evaluated as a measure of the refrigerant level by subtracting the measured temperature from the assigned one;
• characterized in that, at least during prescribable operating phases of the air conditioner use is made for the purpose of assessing the refrigerant level of a maximum value and a minimum value which are set at the start of this operating phase to the last determined undercooling values and are set in the course of this operating phase to the respectively newly determined undercooling values when the undercooling value is greater than the maximum value present at the corresponding instant and the undercooling value is smaller than the minimum value present at the corresponding instant.