I have a 2015 JK Wrangler. I replaced the battery and now the HVAC system defogger blinks for several minutes before the system will kick in. Any ideas why it started doing this?

 

For some reason, the hvac is running a calibration mode, but can't imagine why that has started due to changing the battery. Do you have the Jscan app? If so, i think i'd start by diggin into the hvac module on that to see if anything stands out.

 

Following the topic.


 

Crazy, exact same thing happened to me this weekend.

I swapped in a new battery but also a new radiator and hoses….did have to burp the coolant and thought the blinking was that.

shame I didn’t do things in stages.

My radio also wouldn’t turn on and when I went in JSCAN I had a few hidden codes for “High voltage” and cleared those….radio then worked and AC didn’t blink the first time but now does at startup then works fine

I’m thinking of maybe checking fuses or battery reconnect to see if that resets it

 

I did put in an AGM battery (just the stock replacement Duracell from battery plus)

 

I had the same issue with my 2014 Sahara. Changed the battery and then had the defrost light blinking issue for a while. My temperature knob will only adjust to full heat or full cool now, no temp adjustment in between. The defrost light no longer blinks when I start the jeep.

I’ce found tips on forums that suggest a hard reset on the battery and to check fuses. I’ve done both. The temp did adjust after I did a hard reset, but only once.

I think I’m out of options and will need to by a new control unit unless anyone has other ideas to try.

Any help is appreciated.

 

Had the same thing happen after a battery swap. Drove me nuts for a few days until I figured it out 😡.
The HVAC system just lost calibration, the blinking is it relearning, which is normal.
Try this: > turn key to ON (don’t start) > let it finish blinking without touching anything > turn it off and wait ~30 seconds > start the Jeep
Do it a couple times and it should go away. Hopefully this helps you 👍

 

you may need calibrate Turn Ac to mix and swap from Cold to Hot for few second and turn Ac back that should help you

 

After doing a lot more looking into it, it may be the actuator I put in. After reading a lot of different input, it seems I should have bought a mopar one and not the cheaper one from autozone. I’ve tried the other calibration tips and even bought the JScan app and Bluetooth connector but didn’t have success with it. I’ll bite the bullet and get the mopar one to install before it gets too hot this summer.