The objective of this work is to study the thermal performances of an air-conditioning cupboard conceived and carried out in our laboratory (Solar Applications Laboratory). This a low-cost air-conditioning system allowing exploitation of the available energy sources to low enthalpy. The experimental results obtained made it possible to study the effect of the various operational variables (heat-transfer surface, flow and temperature of water crossing the plaits) on the exchanged thermal power and the total exchange coefficient. The tests show that the air-conditioning cupboard has a good thermal effectiveness of about 80%. In order to dimension this system we propose a model based on the electric analogy which uses convection exchange coefficients. Checking of this model shows a good agreement between the measurements taken and the numerical results.