What the hell is my AC doing?

Hello Gang!!!

My 2017 Runner just starting having this weird little issue and I thought I'd ask here before I take her into the shop, so I'm gonna TRY to explain this as best I can.

It's obviously rather hot all over everywhere lately, so my AC runs mid-high most of the time while I'm driving. When I have my AC on and TURN THE ENGINE OFF and then return to the car to turn the engine back on, the AC will not be running... even though I left the AC knob at wherever its setting was when I turned the engine off. I have to turn the AC knob all the way to 'OFF', wait a few seconds, and then turn it back on for it to start working.

Anyone else have any issues similar??? Please haaaalp

 

This behavior is normal. The air conditioning system in most vehicles requires the engine to be running for the compressor to engage, which is necessary for cooling the air. When you turn off the engine, the AC compressor also stops working. Even though the AC controls might be set to "on", the system won't cool until the engine is running again and the compressor is engaged. The "reset" you're experiencing by turning the AC off and then back on is likely the system re-engaging the compressor clutch after the engine is restarted.

 

Interesting that its 'normal' when I have had the rig for 4 years and have never experienced this.

 

My AC is button (middle) activated when I push it or when I turn the hot cold dial to max ac.

i’ll have to do a test on mine once it stops raining.

 

Neither my 2014 nor my 2021 T4R did I have to move any AC dial for my AC to start again one the engine is stopped and restarted.

 

Interesting, that’s definitely not expected behavior but not sure what is up… You mean you toggle the fan speed knob on the left, right?

 

I experienced the same thing recently that the OP reported. Most of the time the AC turns back on by itself once the engine has completed the start cycle but occasionally I have to manually reset it. Usually I turn it off before engine shutdown but occasionally when I’m doing a quick turn, I leave it on.

 

The AC in my 5th gen at max is the weakest AC flow of all vehicles I’ve ever operated. It’s one of the few things I have really not been satisfied with. That’s all I got, lol

 

I'm confused when you say "I have to turn the AC knob all the way to OFF". The AC is a button you press on the center knob. If you mean the temperature knob on the right, that has to be turned to the coldest setting in order for it to come on when you start the car.

 

I turn the FIRST KNOB TO OFF. Really- its the only knob that says OFF. And sorry im saying AC... but I figured when I said turn the knob to off..... we would know there is only one knob on our heating/ac panel that says off...

 

I TURN THE FIRST KNOB ALL THE WAY TO OFF.. the only knob that says OFF.

 

YES!!!! THANK YOU!!!!!

 

I generally turn off the AC anyway before shutting off the engine, as I've read this more than once across internet posts:


It doesn't bother me to hit the AC button after I've started the vehicle next time out.

 

The AC automatically turns on if you dial your knob to full cold (all the way left)

You cannot undo the AC unless you turn the deal 1 away from max cold

 

Thats probably from like a 1950s car or somrthing.. same as when you were told "turn off ac going uphill to save engine"

Seems asinine

 

I live in south Louisiana where heat and humidity is “King”!
I never turn off the AC prior to shutting down the engine and never had any issues with that mildew growth as you described.

 

WAS TRYING TO HELP. WON'T MAKE THAT MISTAKE AGAIN.

 

That only turns the fan of and on. Has nothing to do with turning the AC on and off. That is controlled by the AC button or turning the temp setting to Max AC.

 

Is the blower pushing hot air or is it completely dead until you cycle it on and off?

 

OP - how long have you waited after you turn the key in accessory mode? Does it work in accessory mode like this? Mine does ----> https://dai.ly/x9nyma0

You should take it in & get it fixed. My 08 corolla, 13 taco, 15 4Runner do not have this problem. My tacos AC has been replaced. Compressor clutch tensioner shit the bed. My 4Runners AC can be screwy, sometimes if the left dial is in between the notches, it won’t engage

 

Condensation, moisture, and mold still work the same way as they ever did. It’s probably a suggestion that prevents mold buildup over the long term. Personally, I’d shut it off a few minuted before turning it off too, if I could ever remember to do that lol

 

Ok. So i started my car up and pushed the AC button on and set to cold, not max AC. Let it run for 5 or so mins and heard it cycle at least 2-3 times. Turned the car off while the AC light was still lit. Came out 10 mins later turned it on the car and AC light came back on without me reactivating it.

 

the ac wont do anything in accessory mode becuase the engine and ac clutch arent spinning and engaged

 

Does it blow just air then?

 

Mine does. I have tested this before. I had the ac knob turned on high and put the 4Runner into accessory mode. It blew cold for about a minute, probably what was left in the line. Then it just blew air. The air outside was very hot, so it blew warm air.

Once I realized the interior was getting hotter, faster...I turned the ac knob to off.

 

yes the fan motor will spin and push warm air

 

I'm curious if OPs truck is even doing this and or do the lights come on at all. OP post a video

 

I'm sure she'll tell you with the caps lock key on.

 

Thanks for the laugh