whats this go to

[copernicusd]

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whats this go to, I have the one before it marked ac, forget if this goes to ac also
just did intake gaskets, and it says timing is on, but its backfiring, so not sure if this is the cause or somethings else

 

[1997chevydriver]

Looks like the ac compressor clutch plug....

 

[skylark]

Looks like the ac compressor clutch plug....

X2.
Check for vacuum leaks.

 

[copernicusd]

thanks, i'll go check