Help with a specific episode

When I was younger, I used to watch this show all the time - even when it went into syndication in the early 70s. I remember one episode in which there is a scene where Sister Betrille and Sister Sixto are cleaning rooms - not sure if it's in the convent or in some other building ( a hotel?) and they were either looking for something or hiding something. It was a rather funny epsiode that stuck with me for a while - I recall Sister Sixto being very nervous and at one point she said something like 'I clean every room with a four on the door'.

Does anyone recall which episode it was? I've been doing a marathon of Seasons 1 and 2 on DVD, and am curious if I will come across it.

I prefer fantasy over reality TV - like Fox News. - B.Streisand