If opening the door of a refrigerator causes an electrical event to occur, one may not open the door on Shabbat. Most refrigerators have an electric light inside that goes on automatically when the refrigerator door is opened. Thus, if the light has not been removed before Shabbat, one may not open the refrigerator on Shabbat. There are also refrigerators where a fan turns on or off whenever the door is opened. These refrigerators and any with similar electrical mechanisms may not be opened on Shabbat.
In contrast, if it has been ensured that opening the refrigerator will not turn anything on or off, one may open the door on Shabbat. Indeed, some permit opening a refrigerator when the compressor has cycled on but prohibit opening the refrigerator when the compressor is off, as opening the door causes warm air to enter the refrigerator. Since the compressor is activated by an internal thermostat, opening the refrigerator may cause the compressor to go on immediately, or at least sooner than it would have otherwise.
However, in practice one may open the refrigerator even when the compressor is off. There are a number of reasons for this. First, it is unintentional: The person opening the door does not intend to turn on the compressor. Second, it is uncertain whether opening the door will cause the compressor to turn on, as it is possible that the compressor was about to cycle on anyway. Third, even if opening the door does cause the compressor to cycle on, this was only done indirectly, via grama, as opening the door does not itself turn on the compressor. It simply causes warm air to enter, which may in turn affect the compressor. Accordingly, one does not need to worry about a case where there is uncertainty regarding grama combined with lack of intent.
For the same reason, one may drink cold water from a water cooler without checking whether or not the compressor has cycled on. One may also enter a room that has a working air conditioner that is controlled by a thermostat, even though opening the door may cause the air conditioner to cycle on. First, it is not certain that opening the door will cause the air conditioner to cycle on. Even if it does cycle on, this was accomplished via grama. Similarly, one may open a door or window in a room that has a thermostat-regulated heater or air conditioner. This is because the person opening the door or window does not intend to affect the machine, it is not certain that opening the door or window will in fact do so, and if the machine is affected it will have been accomplished through grama.
However, many are stringent regarding an oven that is controlled by a thermostat and will not open such an oven when the heating element has cycled off. Since it is a small appliance, opening the door is more likely to cause it to cycle on. To avoid this problem, some ovens have a Shabbat setting in which the oven produces a steady heat and does not respond to a thermostat. When the oven is on this setting, all agree that it may be opened and shut at will.
. As explained in 9:9 above, some permit grama even le-khatĥila, while most only permit it in cases of need. Here, even if the act of opening the oven door will definitely turn on the heating element, since he does not intend to turn it on, it is simply a psik reisha de-lo niĥa lei, which is permitted even under normal circumstances. This point is even more relevant if it is possible that the oven would have cycled on even if left alone. In that case, opening the door accomplishes nothing. R. Shlomo Zalman Auerbach writes this regarding a refrigerator (Minĥat Shlomo 1:10), as do R. Ovadia Yosef (Yabi’a Omer, OĤ 1:21) and R. Eliezer Waldenberg (Tzitz Eliezer 8:12). However, many recommend being stringent and opening the refrigerator only when the compressor is already on; only then is it impossible for opening the door to cause the compressor to turn on, as it is already on. Even though the influx of warm air will lead the compressor to stay on for longer, this is not prohibited (Responsa Har Tzvi, OĤ 1:151; Ĥelkat Yaakov 3:179). Nevertheless, the bottom line is that one may open a refrigerator without checking whether or not the compressor is on.The law regarding opening a refrigerator is more lenient than the law regarding opening an electric oven. There are two reasons for this distinction. First, an oven is small, and thus opening the door is likely to cause it to cycle on. There is a slight possibility that this would not be considered grama, but rather a direct action. In contrast, a refrigerator is large, and it is unlikely that opening the door will affect it immediately. If this were to happen, it would definitely be considered grama. Second, according to many poskim, turning on the refrigerator’s compressor is only a rabbinic prohibition, since there is no heating element (above, n. 1). In contrast, turning on the oven’s heating element is prohibited by Torah law according to all opinions. Reflecting this distinction, SSK 1:35 is stringent about opening the door of an electric oven, while when it comes to a refrigerator he records the lenient position as well. In contrast, Igrot Moshe, OĤ 4:74, Bishul 28 is lenient even in the case of an electric oven with a thermostat. He maintains that one may open the door even when the oven has cycled off, because it is an uncertain psik reisha in the case of a rabbinic prohibition (as it is performed via grama), and such a combination is permitted. Regarding opening the door of a room that has a radiator or air conditioner, almost no one is stringent. Since there is a relatively large distance between the door and the air conditioner or radiator, even those who are stringent would agree that this is considered grama. See above 10:17.