When we turn the heat on almost every time the unit goes into defrost we get a kind of stale metal smell coming out of the vents. When we run the ac in the summer we don't have this problem. Its starting to get really annoying for my girlfriend and I.
We got the ac tecs to come out and check it out they sprayed a cleaner on the coils because they thought it was them. It seemed to mask the smell for a while but after about a week it came back in full force. Any ideas would be appreciated.

It is probably still from the indoor coil. It is called the dirty sock syndrome. It is actually bacteria that causes the smell along with mold. Sometimes it takes more than one treatment. Do a Google on dirty sock syndrome for more info.

Yea that's what they said also but I wouldn't think 2 weeks after they install the ac system that it would get that bad

It's starting to get really annoying for my girlfriend and I.If you think it's annoying now, just wait 'til you're married... :D Sorry, just kidding... perhaps the odor is coming from something that is in contact with the auxiliary heater strings, which are usually activated during defrost...

If you think it's annoying now, just wait 'til you're married... :D Sorry, just kidding... perhaps the odor is coming from something that is in contact with the auxiliary heater strings, which are usually activated during defrost...
You know your not kidding... Ill have to call the ac people again and see if they will come check/clean them again. The odd thing is though that when they came last time they put it in defrost and it didn't make the smell.
Quick question when in defrost its still pumping air into the house should it be heated air or just like having a fan on?

If working correctly, there should be some warmth to the air during defrost.