art that a few reasons can exist reason for the lack of response in the evaporator temperature at this time one being frost buildup on or near the sensor located on the evaporator fins another being a supply of cold contents in the refrigerated space in fact it takes less than one minute to see a rise in the zone 3 bypass tube vapor temperature while it takes over twelve minutes before the first change is noticed in the refrigerated space line 164 referencing line 167 on the graph fig5 at this point the ventilation fan was turned off to show the effect of ventilation fan failure in a less than desirable ventilation arrangement such as upper sidewall vent in a camper slide out room again an immediate response from the vapor temperature of the zone 3 bypass tube 163 and now gradual response from the temperature sensor in the refrigerated space 164 it should be noted that within just minute of ventilation fan failure the zone 3 temperature sensor represented by line 163 can determine that the refrigeration process is no longer continuous and take several actions to correct the rise noted in the zone 3 vapor bypass temperature or interrupt power to the absorption cooling units heat source if corrective measures fail to reduce the vapor bypass temperature it is the intention of the current invention to conserve power and limit thermal stress on the cooling unit if the refrigeration process is observed to be no longer continuous it should be obvious from the graph data that the.