# Defroster runs AC

**URL:** <https://community.cartalk.com/t/defroster-runs-ac/98909>\
**Category:** Maintenance/Repairs\
**Tags:** legacy, subaru\
**Created:** [January 22, 2017, 6:01pm UTC](https://community.cartalk.com/t/defroster-runs-ac/98909 "2017-01-22T18:01:43Z")\
**Posts on this page:** 1\
**Showing post:** 3

<div class="post-metadata">

**Author:** ![asemaster](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@asemaster](https://community.cartalk.com/u/asemaster)\
**Post date:** [January 22, 2017, 6:05pm UTC](https://community.cartalk.com/t/defroster-runs-ac/98909/3 "2017-01-22T18:05:19Z")

</div>

All cars run the AC compressor when the defroster is on. It’s not counterproductive. The AC removes moisture from the incoming air in order to keep the windows clear from fogging up.

There are temps where the AC won’t run, the pressure switches and sensors will take care of that and turn off the compressor if the system is in danger of icing up.

---

_[View the full topic](https://community.cartalk.com/t/defroster-runs-ac/98909)._