Meaning:

“中央空调” means “central air conditioner,” and “男” means “man.” A popular phrase coined by Chinese netizens, this term refers to men who are gentle and considerate towards every woman around him to the extent that many may in the beginning mistake his kindness for a romantic interest. Normally, this type of guy has many female friends but not a girlfriend, since women prefer another type called “暖男” (literally, “warm guy”) who are kind and considerate only towards those they care for, but not every woman they’ve come to know.

Example:

A: 小李有女朋友吗？

Xiǎolǐ yǒu nǚpéngyǒu ma?

Is Xiao Li seeing anyone?

B: 没有。

Méiyǒu 。

Not really.

A: 奇怪啊。他似乎很受女生欢迎。

Qíguài ā 。Tā sìhū hěn shòu nǚshēng huānyíng 。

Isn’t that weird? He seems popular among girls.

B: 他是中央空调男，对谁都好。女生真心喜欢的是只对自己好的男生。

Tā shì zhōngyāng kōngdiào nán ，duì shuí dōu hǎo 。Nǚshēng zhēnxīn xǐhuān de shì zhī duì zìjǐ hǎo de nánshēng 。

He’s a ladies’ man and nice to everyone. Girls often fall for a guy who is nice to them exclusively.