AC won't blow cold after disconnecting 12v battery

Hey guys...so I snapped a lug, and long story short, I had to disconnect the battery to remove the front left brake and pull the old lug out. Well, I attempted to, anyways...supposed to go by a friends house today and finish the job.

Anyways, the important part is the battery was disconnected, then reconnected. While reconnecting, the post on the battery seemed to have a little bit of give to it (so I'm already thinking that it's gonna be replaced). However, the car starts and drives fine, except the AC doesn't blow cold. The fans work, the temp control works, but if I press the AC button, it doesn't even light up. AC worked fine when I got the car (I actually just got it on Friday) otherwise I would have said "no thanks" to the purchase.

Does the 12v battery have anything to do with the AC? Or does that run off the hybrid battery and the engine? I know the computer can work in mysterious ways on a Prius, but as I've only owned the car for 4 days, I'm still sussing them out.

Thanks in advance, and happy to be counted amongst y'alls number!

 

It was pretty night/day after disconnecting/reconnecting the battery. Blew super cold on my way home from work yesterday, then when I turned it on again, nothin but just air.

 

Looks like the fuse is fine. I'm wondering if the post bending damaged the electrical connection to the point where it's giving funny readings to the computer or something.

 

Just took a look at the battery on my lunch break, and the negative terminal is borked. It's cracked and looks like it's hanging on by a thread. Either I'm gonna need to be more careful torquing stuff down on this car, or the thing was already cracked. I'm gonna see what I can do about a replacement battery and see if that fixes things.

It's weird, because the car starts and everything. So voltage is getting there. But I've had weird problems where the cause was low voltage from the battery before, so maybe the AC draws some sort of power from the 12v that it isn't getting? I'm with you, I don't see how the 12v would be the problem.

 

Yeah, I'm gonna grab a reconditioned battery after work, I'm hoping. Can't afford a new one at the moment, but hopefully this will sort the problem out. I'll make sure and check in and say whether this was the issue or not.

I can't really figure out what else it might be. I remember it blowing cold when I left the gas station a half mile from home, then once I'd disconnected the battery, nothin'. AC button doesn't even light up.

I'm wondering if there's some sort of current that goes to the AC from the 12v that's used for purposes other than running AC (such as sensor checks or something) but I don't know enough about the electrical system to figure out whether this would be the case. I may try another relay though, just to be sure it isn't that.

 

OK, new 12v battery is in and works fine. Still no AC, but it does seem to cool for a second (literally like a second of coolER air) and then shut back off, if that makes sense. Will update shortly, about to check fuses.

 

Pressing the button gives me nothing. Doesn't come on at all, nor does it change what's coming out of the AC. This is making me tend toward thinking it's a fuse or a relay.

So noob question...when you say relay, do you mean the fuses, or is there another thing I should be checking? At first I was thinking fuse/relay were the same thing, but I just wanna be sure before I start saying "yeah, I checked that."

 

Well, checked all fuses, but I'm still researching relays to figure out which does which. I haven't checked the fuses in the inverter itself, as you posted in the video above, but I might try that tomorrow afternoon once I've got time & daylight. Today was spent replacing the wheel stud and getting the new battery in, unfortunately.

I found the Haynes manual at the Dallas Library, so I may go by and grab that tomorrow. It's supposed to cover 2001-2012 Prius, so hopefully the info I'm looking for about where to find the relay and how to check it will be in there. At this point, I'm convinced it's probably the relay, since the AC switch is the only one on the climate control panel that doesn't light up. That at least tells me that either the LED is dead (and honestly, I don't remember seeing it light up before, so maybe it was in a pre-failure state or the LED is just dead) or the switch itself isn't receiving any power from somewhere. I've never seen a single switch on a panel fail to light up like that, and knowing what I know about LEDs, I'm not really convinced that this one went kaput after only 6 years...stranger things happen I suppose, though.

Anyways, like before, I'll check back for posterity's sake so the next guy doesn't have to wrack his brain.

 

THE PLOT THICKENS.

Okay, so today, I found another post in Prius chat that detailed how to run a "chicken dance" A/C diagnostic to return a trouble code. What I learned was

a) I'm getting no trouble code from anything in the A/C.
b) The LED light on the A/C button definitely works.

I have the Haynes book now, I'm just working my way through it, trying to figure out which relays are which, and which ones might have gone bad. I'll be checking here if you guys have any suggestions.

I'm starting to wonder, though, if maybe the button on the control system itself is bad? What would be the way to test that, I'm assuming I'd have to touch a wire to another wire and see if A/C kicked on? If so, how was A/C running when I bought the thing a week ago?

I'm goin down the rabbit hole, boys. I'll check back when I know something certain.