AC light comes on when I turn on my heater

Is this supposed to happen? Whenever I turn my heat on my ac light is on. Is this supposed to happen. I can't shut it off either. But I noticed that I don't have my lowest setting for heat. The second, third and fourth placements all work but won't on the lowest. Does this mean I need to replace my blower motor or is it a wiring issue. The previous owner said the blower motor needed to be replaced but it seemed to work fine when I took it out?

 

Blower motor going out would just affect whether you get air pumping or not. What setting is your vent control on? Some settings like defrost will turn on the AC regardless of where the temp setting is set.

 

Most modern vehicles turn on the ac with at least the defrost setting. Ac dries the air, helps clear a fogy windshield.

 

Yep, defrost. What ^^^^^ said

 

I don't know about yours but my 98 has a button on the heater controls that turns the AC on or off regardless of what the heater controls are set at.

 

My 98 has no engine in it so I can't get back to you on that one lol. I wish my 08 had that though!

 

My 99 turns the compressor on when the defrost setting is on. The AC light on the button is off though. You can hear the engine change tune when the compressor engages and disengages. If you are still unsure, pop the hood and watch the AC clutch. You can see the compressor start and stop.

 

Okay Thanls guys I'll have to check it out. Because I know whatever it was on it wouldn't shut on. The light stayed on. So I'll take a check today

 

I also have a 99 Tacoma and was wondering if there is a way to make the AC not cut on when using defrost??

 

You need @magog45's magic button.

 

I have a button...the AC just comes on no matter if the button is pushed on or off.

 

I think mine is the same way - there's got to be a way to change it. It will possibly involve cutting a wire that runs from the HVAC controls to the AC relay I'm guessing. @BartMaster1234, @nzbrock, @mechanicjon, @Glamisman you got a wiring diagram for HVAC?

 

Give me a sec. I have an extra AC button if yours is defective.

 

Thank you! But I think the goal is to cut off AC from turning on when the vent switch is set to defrost / defrost and lower vents. Does your AC button turn the AC off when you're using defrost?

@ToyotaJim I know the feeling - when you want air on the windshield but don't want to run the AC.

 

Here's the Air Conditioning wiring schematic and literature for a 2000.

 

Looks like you could mess with that switch that goes between the defrost control and what I'm guessing is the AC relay on the first page of "Air Conditioning.pdf" by having it stay open even when it's supposed to close on defrost.

 

Yeah, I just like being able to use the heat without the dreaded AC compressor making my truck rev high while I'm trying to get ice off my windshield. if its as easy as cutting a wire...someone help me figure out which one!!

 

Sweet guys thank you. I'll have to look into that. That's not gunna make my ac not work though? Or will the ac be fine by itself.

 

From the diagram it looks like there's two separate ways to turn on the ac. The push button AC switch and a switch behind the dash in between the vent switch and the AC relay. That's my unprofessional uninformed opinion, but if you feel comfortable taking your central dash out, you can check and see if that switch is easily accessible. My guess is that's it and it would solve your problem. Always worth waiting for someone to chime in that knows for sure. Maybe @Speedytech7!

 

Are you tapped into my browser history or something? I was literally researching Toyota A/C function on my Land Cruiser, trying to figure out the various triggers and what causes it to turn off. Turns out it turns off when engine coolant reaches 226F for safety and when the pressure in the condenser reaches 412psi. Trying to figure out the best method for triggering an AUX fan to come on.

Anyway, when you physically look at the wiring for the A/C switch on cable actuated Tacomas the A/C switch is a separate part and the light should only come on if the HVAC blower is on and the switch is pushed, now on later Tacomas I'm not too sure, they may also come on when you have the vent position set to defrost (demist) as A/C air is drier than just heated air. I'd consult the Electrical diagram for your model year if you truly want to know what the triggers are.