99 Ford explorer

I bought it a month ago and drove from VA to TX. Since then the check engine has come on and it received the P1151 code from advance auto parts. I know it has an exhaust leak too. Today when i turn on the A/C theres a clicking in the dash and the engine revs a little. has anybody else ever had this problem? if so, what are my options?

Thank you!
Bree

The engine will rev a little when the AC compressor engages because it applies more load to the engine. The engine would stall if it didn't.

This is your Idle Air Control valve at work (IAC). If your AC compressor is not engaging and you only get a clicking noise, you have an electrical bug somewhere. Or at least, that's what I get out of your post.

WHERE'S THE POLL?