a/c, remote start issues after battery disconnect.
 

New here, i have an 08 mazda 3 sport/touring 2.3l. a few weeks ago it was seviced and they disconnected my battery. now when i start with remote start it runs maybee 5 seconds and dies. also the a/c has gone crazy, sometimes the clutch kicks in and it works for a couple hours, then it stops for a while. sometimes it works on cold starts, sometimes it kicks in later in the day. no real pattern. i have been searching all day, cant find much info except maybee the remote start needs tach signal reset? thanks in advance for any help.

That tach reset comment is a good start. Is this an aftermarket system or factory?
I've put in a couple aftermarket ones and there are settings for what the good tach speed is. You may need to put it into learning mode and then start it to get it working.

As for the A/C - you're probably low on refrigerant, that'll happen over time since the fittings are not perfect seals.

the remote start is mazda, dealer install. i actually fixed both problems last sunday. after much research i turned off all accessories, disconnected battery, waited 10 min. turn key to ON, reconnect battery. a/c defaults to on position, turn a/c off. turn ign off. start and let idle 20 min with no accessories. turn on a/c, blows ice cold instantly and has worked flawless ever since. remote start now operates perfectly. go figure!

I remember some odd sequence like that someone told me about an old buick - something with having the computer relearn engine paramaters after replacing the battery... crazy.

But glad that you found a fix :)