compressor or vac leak?

[12340987]

Sometimes I notice while sitting at traffic lights a click, similar to the a/c compressor or perhaps a climate control thingy clicking on.
I have the a/c button set to OFF. RPM increases a few hundred (up to around 1k). It's very annoying as it causes vibration. It's especially noticeable when the engine is cold. Still happens when I go into neutral. I think it only happens when the heat is on.
The car seems to lose power, which suggests a/c to me. Good thing this doesn't have cruise control or it would probably be ploughing through crowds of people of its own accord.

Edit-
Wait a minute, I see from http://bbs.legacycentral.org/viewtopic.php?t=14947 that the a/c compressor turns on when in defrost... Why is that? to reduce moisture?

Nevermind then, I guess that explains a lot.

[wiscon_mark]

yes, defrost automatically triggers the A/C because you want to remove moisture from the windshield. If you want to eliminate that, put it on defrost/feet setting, and the compressor won't turn on.

[Legacy777]

ANY defrost setting, including defrost/feet should trigger the A/C.

[wiscon_mark]

ANY defrost setting, including defrost/feet should trigger the A/C.

i never noticed the lag when I'm on defrost/feet

I assumed the orange color on the defrost only button indicated compressor use. I assumed that the defrost/feet didn't set off the A/C because it had white symbols like the other HVAC settings. I know it does on our Honda Civic, but doesn't on our Honda Odyssey...harder to tell on the subaru, because there's no electronic button for the A/C, only a mechanical push button with a light.

[Legacy777]

I just checked....a/c compressor does kick on in the def/heat setting.

[wiscon_mark]

okay, good to know