Air conditioner on when it shouldn't be.

Let me give a little background before getting to the problem. I bought my '07 Taco last Spring after the warmer weather settled in. Once Fall and Winter rolled in, I was somewhat dismayed that the heater was so wimpy. I expected better.

So this Spring we had several days that were cool (50-60) with bright sunshine. In that situation I like to turn the selector to "Defrost" or "Defrost/Console" so cool outside air is coming in up above, but without a draft on my lower body which is in the shade. I noticed the incoming air was awfully damned cold, like the A/C was on. And it was!

What I found is that the A/C comes on whenever the selector is in either "Defrost" or "Defrost/Console" position. The A/C indicator light does NOT come on so you don't realize the A/C is on. Pressing the A/C button does nothing. It doesn't matter that the heat is on/off.

Also, the air-recirculate button goes non-functional: pressing the button does nothing. I.e. the indicator light does not come on and the air is outside air.

So I re-read the manual and found some threads in this forum that touch on this issue but don't address it directly. I just can't believe this is intended by design!

If Toyota engineers believe that the A/C MUST be on whenever air is being blown on the windshield (spring/summer/fall/winter), they're smoking something they shouldn't. If they want to turn the A/C on automatically, fine, turn on the A/C indicator light and allow me to push the button to turn it off if I want. Turning it on without letting the driver know is wrong, and cancels out the heat during the winter.

Also, the driver should still be able to choose recirculated air when driving through nasty dust or chemical smells when Defrost is selected.

Does everyone else's truck do this too? Or is mine somehow broken? I bought it with 61K miles on it.

 

Absolutely normal.

 

In order to properly defrost/defog you need dry air. One byproduct of "conditioned" air is the moisture is removed. When in defrost or defrost blend you may need to adjust the temp up to your comfort level.

The recirculation mode is canceled in either defrost mode to prevent moisture build up....which would defeat the purpose of the defrost

 

Really?! That's ridiculous. In really cold weather, when your windshield is frosted both inside and out, you want as much heat blowing on it as possible. Turning on the A/C is stupid, and besides, the humidity of the air is so low, you don't need the A/C's dehumidifying.

 

Not sure where you live, but here in Colorado the RH is often less than 10% even when it's warm. In winter, with temperatures in the single-digits and teens, there IS no moisture in the air to start with. Humidifiers are standard features out here.

 

Sorry brother. But you're mistaken on this one. In cold or cool weather you may need to turn your temp knob up for warm air. The A/C is providing you drier air to assist.

Air conditioning is not just cold air. It's "conditioned" air.....as in dry. You determine the temp setting

 

This is normal but I couldn't stand the truck doing it automatically also, I'd rather control it myself. Do this mod and the HVAC will function like a car made before people became too lazy or unmechanical to oprate a car properly
https://www.tacomaworld.com/threads/a-c-on-with-defrost.7160/

 

As far as I know, all manufactures do the same thing regarding defrost... Because it works. At least it's not a climate control system like I have in both Avalons. The '01 Avalon is the worst, if you select lowest temp to cool, it assumes recirc (max) and then "remembers" this recirc setting even after shutting the car off and restarting with no a.c. running. Very annoying... (Not in defrost mode however, which is an independent control thankfully) The car does have 226k miles, so not everything works perfectly anymore. Still, from a reliability standpoint, the '01 is better than the '06.

 

Sorry, I totally disagree. Air conditioners lower the humidity by cooling the air, raising the RH, and allowing now excess moisture to condense on its cold coils. But there's no way a typical automotive A/C can cool air that's already at 10F, or lower, thus it can NOT lower the humidity of that air.

In fact, no automotive A/C that I know of will FREEZE water on its coils, thus when the intake air is less than freezing, the A/C is totally ineffective.

Secondly, starting with 10F, 10%RH air, HEATING that air lowers the RH, the now warmer air can absorb more moisture, which is what you want. Of course in this case, you need to MELT the frost on the windshield first, so you want the hottest air you can get. Another reason you don't want the A/C to be on at the same time the heater is.

The A/C should only be turned on to DEFOG, near to or above 32F, not defrost.

 

Looks like operator error to me

 

Absolutely perfect, and easy! THANKS!

 

Looks like a moron to me.

 

Says the guy who can't figure out how to operate basic car controls. Hahahahahahaha

 

Nearly every domestic vehicle produced in the last 40 years that as A/C...as an A/C/defrost link.

Domestic manufacturers figured out long ago that the average American consumer was not smart enough to know how to operate an HVAC system in varying weather conditions.

Toyota, on the other hand, was a bit slower to realize this...as were most Japanese manufacturers. It wasn't until the early 90s when Toyota's N. American sales really began to climb, particularly with the Camry and Corolla, that they figured out they had a problem. They began to field large numbers of reports of windows foggy up...particularly in cool wet conditions. They began sending out supplemental info to owners informing them to turn off the recirculation mode, turn on the A/C and adust the vent mode and temperature to match the conditions.

Then by the mid 90s they began to adopt the link technology from the Big 3 as a standard feature.

 

You came here for answers, right?

 

Go correct an engineer...not me.

Have a nice day

 

Everything does this. Also, I believe most ac systems shut off when it gets down to freezing. We had a chevy work pickup that would instantly fog up when it dropped to freezing and the ac shut off

 

AC evaporator coils freeze up all the time if the refrigerant charge is low, and occasionally even if properly charged in extremely high humidity ambient conditions...

 

If you are getting frost "inside and outside" the air isn't as dry as you think.