Help Needed: Unlink A/C to Defroster

[stran]

I don't like the way how the A/C has to be on when I turn on the front defrosters. I think there are two ways to fix this: fake out the detector switch so the car doesn't know you turned on the defroster, or kill the circuitry that automatically turns on the A/C.

In case you don't have the Factory Repair Manual Handy:
http://www.etimago.com/yaris/repairmanual/EWD.pdf
http://www.etimago.com/yaris/repairm...nditioning.pdf

This might get a little technical:
Option 1
One guest is that the switch could be inside the control knob itself, and the signal could be turned off by shorting the signal wire or soldering in a resistor. Take a look at page 245 of the Air Conditioning manual for more info about this. Or there could be a switch in the air damper that controls flow to the front defroster. See page 10.

Option 2
The Electrical Wiring Diagram Manual (filename: EWD.pdf) on page 239, 240, and 330 mentions "Defroster Mode Detection SW" in the context of air conditioning. SW means switch. The problem is that I don't know where this switch is physically located in the car. The diagram on page 50 and 52 might help answer this question but I can't put the two together.

Any help is appreciated, and I know I'm not the only person who wants to get rid of this.

[TheRealEnth]

i really dont mind?

[IllusionX]

there IS a switch inside the knob that activates the compressor AND THE BUILT IN HEATER...

you do not really want to get beyond that that in messing around the wires...

[auxmike]

What about in the deep of winter, will the A/C still kick on?

[stran]

Originally Posted by IllusionX

there IS a switch inside the knob that activates the compressor AND THE BUILT IN HEATER...

you do not really want to get beyond that that in messing around the wires...

Except the connection to the heater is probably via a mechanical linkage. I know that the vent knob operates via a mechanical linkage. With the car off and there's no power, you can still switch between the vents. On luxury cars I've driven before, the soft buttons activate a little motor that open and closes the damper that only works when the car is on.

[CTScott]

Originally Posted by stran

Except the connection to the heater is probably via a mechanical linkage. I know that the vent knob operates via a mechanical linkage. With the car off and there's no power, you can still switch between the vents. On luxury cars I've driven before, the soft buttons activate a little motor that open and closes the damper that only works when the car is on.

The knob that changes where the air is blowing does so by cable as you mention. Here are some pictures of what the back of the switch assembly looks like:





From this thread about changing the bulbs:
http://www.yarisworld.com/forums/sho...light=led+dash

If you look at the close-up picture above the outer knob turns a plastic gear. I would bet that there is a boss on the gear that bumps a switch that parallels the AC switch. If so, you could just clip the boss...

[jambo101]

Seeing as you have it all apart anyway can you give us a pic of the cam/boss that activates the air while in defrost mode? dont know why Toyota couldnt have given me the option of defrost with air on or off,like its only a matter of pushing a button if i want the air on.

[CTScott]

Originally Posted by jambo101

Seeing as you have it all apart anyway can you give us a pic of the cam/boss that activates the air while in defrost mode? dont know why Toyota couldnt have given me the option of defrost with air on or off,like its only a matter of pushing a button if i want the air on.

I haven't actually pulled mine apart. I just remembered seeing the picture of it pulled apart on that thread. Based on the EWD's I think that the "option" is based on whether or not you have the "cold weather package".

[CTScott]

Originally Posted by stran

I don't like the way how the A/C has to be on when I turn on the front defrosters. I think there are two ways to fix this: fake out the detector switch so the car doesn't know you turned on the defroster, or kill the circuitry that automatically turns on the A/C.

In case you don't have the Factory Repair Manual Handy:
http://www.etimago.com/yaris/repairmanual/EWD.pdf
http://www.etimago.com/yaris/repairm...nditioning.pdf

This might get a little technical:
Option 1
One guest is that the switch could be inside the control knob itself, and the signal could be turned off by shorting the signal wire or soldering in a resistor. Take a look at page 245 of the Air Conditioning manual for more info about this. Or there could be a switch in the air damper that controls flow to the front defroster. See page 10.

Option 2
The Electrical Wiring Diagram Manual (filename: EWD.pdf) on page 239, 240, and 330 mentions "Defroster Mode Detection SW" in the context of air conditioning. SW means switch. The problem is that I don't know where this switch is physically located in the car. The diagram on page 50 and 52 might help answer this question but I can't put the two together.

Any help is appreciated, and I know I'm not the only person who wants to get rid of this.

I looked at the EWD. To disable it you would need to cut a trace on the printed circuit board for the AC switch assembly. I would have to pull one apart to figure out which trace, but the other option is to replace the switch. The EWD indicates that there is one "w/ Defroster Mode Detection SW" and one "w/o Defroster Mode Detection SW".

[Revsson]

Originally Posted by stran

I don't like the way how the A/C has to be on when I turn on the front defrosters. I think there are two ways to fix this: fake out the detector switch so the car doesn't know you turned on the defroster, or kill the circuitry that automatically turns on the A/C.

In case you don't have the Factory Repair Manual Handy:
http://www.etimago.com/yaris/repairmanual/EWD.pdf
http://www.etimago.com/yaris/repairm...nditioning.pdf

This might get a little technical:
Option 1
One guest is that the switch could be inside the control knob itself, and the signal could be turned off by shorting the signal wire or soldering in a resistor. Take a look at page 245 of the Air Conditioning manual for more info about this. Or there could be a switch in the air damper that controls flow to the front defroster. See page 10.

Option 2
The Electrical Wiring Diagram Manual (filename: EWD.pdf) on page 239, 240, and 330 mentions "Defroster Mode Detection SW" in the context of air conditioning. SW means switch. The problem is that I don't know where this switch is physically located in the car. The diagram on page 50 and 52 might help answer this question but I can't put the two together.

Any help is appreciated, and I know I'm not the only person who wants to get rid of this.

It doesn't say it in your profile, but I assume that since you joined in 2007,
that you drive an '07 LB?
Just trying to clarify if there can possibly be any difference in the model
years for the A/C.

[jambo101]

Originally Posted by stran

I don't like the way how the A/C has to be on when I turn on the front defrosters. .

I dont like it either,seems like a waste of energy,all previous cars i've owned never had air and i never had a defrost problem, but what is needed to defeat this operation looks like more trouble than its worth so i'll just crank up the heat a little more to overcome the permanent air when in the defrost mode

[floydisrock]

The ac compressor in a vehicle should be run to prevent clutch and bearing problems.
Every Car I've owned mentions running the ac at least once a month.
I'm guessing they just let the compressor run,so they don't have so ,many warranted a/c compressors to replace.
I wouldn't worry about the few cents your going to save disconnecting the unit,I would worry about replacing a $1000 a/c compressor.

[jambo101]

My winter setting is the defrost/floor position for the entire winter so i guess i have no other option than to have the air running all winter whether i like it or not.

[IllusionX]

Originally Posted by jambo101

My winter setting is the defrost/floor position for the entire winter so i guess i have no other option than to have the air running all winter whether i like it or not.

you don't NEED to run with defrost/floor all winter long... put it back to the floor only when the front window is defogged.

[jambo101]

Originally Posted by IllusionX

you don't NEED to run with defrost/floor all winter long... put it back to the floor only when the front window is defogged.

Tried that and the windows start fogging up again,seems some airflow is constantly needed on the window to keep it fog free' but just warm air will do the job once the car is at operating temperature,at that point the air is no longer needed but there is no way to turn it off and still have airflow over the window.

[stran]

Originally Posted by jambo101

Tried that and the windows start fogging up again,seems some airflow is constantly needed on the window to keep it fog free' but just warm air will do the job once the car is at operating temperature,at that point the air is no longer needed but there is no way to turn it off and still have airflow over the window.

agreed. i also like having warm air diffused instead of concentrated at my face or feet, and the best way to do that is through the defroster vents.

[eTiMaGo]

winter or not, I believe the main reason for the AC kicking in is to dry out the air to help with the defrosting/defogging itself?

[stran]

Originally Posted by Revsson

It doesn't say it in your profile, but I assume that since you joined in 2007,
that you drive an '07 LB?
Just trying to clarify if there can possibly be any difference in the model
years for the A/C.

I have a '07 hatchback.

PS How do I subscribe to a thread if I forget to do it when I post?