Confusion about possible double condition in article about fires

Question

I'm reading this article about how air conditioning and electric fans turn into a lot of fires. The final sentence has put me in a little loop though. I cannot tell if there is a double conditional being used here or not.

There is a と but then a little later on there is あったら. I am not really sure what is intended by the と. I know that と has multiple meanings, but I am unsure if it should be translated to a 'if' or a 'when'. Also another major bump for me is the あったら as I have only seen the たら-form being used as a conditional marker. It seems really strange to me to have a double conditional, but ultimately I am unsure

特に２０年以上使っている古いエアコンや扇風機を使うときは、変な音がするなどいつもと違うことがあったら使わないでほしいと言っています。

My translation: The case for old air conditioning units and electric fans that are in use for at least 20 years, which (if they? [based on と]) are always making strange sounds and (if? [based on たら-form]) they are unusual, these are the ones you do not want to use they said.

Answer 1

「特に２０年以上使っている古いエアコンや扇風機を使うときは、変な音がするなどいつもと違うことがあったら使わないでほしいと言っています。」

There is no "double conditional" used in this sentence. There is only one, which is 「あったら」.

The 「と」 in 「いつもと違う」 is not the conditional 「と」. You cannot place a simple word like 「いつも」 right in front of the conditional 「と」 in the first place. It would generally take a whole mini-sentence or a verb phrase for the following 「と」 to indicate a condition.

This 「と」 simply indicates a standard for comparison. The standard is 「いつも」 here. If you have an いつもと違う something, that will be a deviation. Thus 「いつもと違う」 just means "unusual" here.

The structure of this sentence is:

"When using a (certain thing), they would rather not want you to use it if (Conditions) such as (Example) are found."

(certain thing): ２０年以上使っている古いエアコンや扇風機

(Conditions): いつもと違うことがある

(Example): 変な音がする

In 「～～など」, "～～" is an actual example of what is described after the 「など」.

Thus, the sentence means:

"In particular, in using an old air conditioner or electric fan that has been in use for over 20 years, they are saying that they would rather not want you to use them if you found unusual things with them such as a strange sound being made."

Answer 2

変な音がするなどいつもと違うことがあったら

in this case you are dealing with two fairly commonly heard expressions:

いつもと違う - which means "different from (the) usual (X)" or "different (X) from the usual one"

this phrase is then followed by があったら , which, as you correctly identified, is the conditional of ある and can simply be translated as "if"

As @Chocolate pointed out to me below, the use of など after 変な音がする makes "strange sounds" one of many possible "different from usual" conditions,

so the entire phrase would become:

"if anything is unusual/out of the ordinary such as it making strange sounds..."