So to explain this, my A/C button came off a few weeks ago, and some what my A/C started only working whenever the compressor was working AKA when you turn the air to be blown to the windshield. I ordered a new A/C button and installed it and all. I push the button and A/C start blowing like normal. Now my Issue is that somehow A/C start blowing no matter what when set into the windshield setting. (blowing air to the windshield to defrost). And yes it has the A/C light turn on, even if the A/C button isnt pushed in. Its like if the car says If the compressor runs, it runs the A/C.

This is gonna be problem for winter having A/C trying to cool off the so much needed hot hair to defrost my windshield. It already is during rainy day creating fog on my windows instead of keeping them clear of fog. Ill try to film a video if you uys dont understand my issue.

Thank You!

I really stoned so maybe I'm way off base here, but it sounds like you're just describing the normal operation of your HVAC. When you set your system to defrost, the a/c will always kick on to dehumidify the air so the windows don't fog up. This is normal and nothing to be concerned about. The air will blow hot even with the A/C on to dehumidify the air first.

Sorry if this isn't what your describing...super baked so...

This is %100 normal. All cars ac turns on when switched to defrost. Your air conditioner (whether it’s set to cold or hot) condenses the moisture out of the air into water. This condensation is vented through a drain hose that runs from behind your glove box out the bottom of the car. The system then pumps dry air into the car. When you turn on the defroster, it pumps dry air up toward the windshield. This helps to evaporate the moisture.




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Your problem is a little hard to understand the way you're describing it but the AC should come on when the defrost is on. The ac dehumidifies as well as cools. Now you should be able to turn the AC off when you press the button. I have a Limited so the controls are different but I believe the AC button is basically the compressor control button which is how it works on my 99 Limited. When I press defrost the AC automatically comes on (the compressor) and dehumidifies. At this point, you can turn up the heat control to get the dehumidifying effect along with the defrosting effect. I also can turn the compressor off while remaining in defrost. If your AC button isn't turning off the compressor then the button may be bad. And yes your AC is always on when your compressor is on.

+1 for dehumidification. It overrides to A/C operation as hot air isn't all the will defrost. Air needs to be dry (dehumidified) as well. You're fine homre. Roll with it.

And don't worry about winter. The compressor won't cycle on when the temp is below 30 or so. There is the pressure-temperature thing going on with refrigerant so the colder it is the lower its pressure will be and that will keep the low side switch off.


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On my '97, the defrost-auto A/C can be disabled by finding the small connector behind the HVAC display panel, and disconnecting it. Unhooking it is like a trip back in time to my '91 Toyota truck, which didn't have the auto A/C feature.

I'll be doing this the next time I have the dash apart... My favorite Southern California HVAC setting for the winter is defrost/floor with no heat and no AC going. Fresh cool air, not blowing on my face is nice.

Any modern car (maybe mid-90's and up) turns on the AC compressor in any defrost mode, so this setting can't be used unless you leave the fan in the off position.

-Charlie

Sorry for the very late reply, but before my button broke, the compressor would start except cold air would not be blowing out it would be dehumidified air. Right now it also cools off the air instead of only dehumidifying it. Ill be shooting a video about it after work so it can be better seen. its just a pain atm since when i try to only have outside air dehumidified to blow against the windshield in rainy condition at night, it blows the A/C aswell cooling the windshield off and creating a foggy effect. i didnt had the A/C blowing before when in defrost modes. hopefully the video will solve something i know my english isnt great :x

The only way to dehumidify without blowing cold air is to turn on the defrost and set the heat up to whatever level you want. This is how they all defrost systems work, toyota or not.

Normally I only run my defrost long enough to get rid of the excess moisture on the windshield or side windows then shut off the compressor while leaving vents the same (towards windshield) but with venting set to exterior to keep bringing in drier air. Luck.