Any ideas on how to remove "idiot proofing" in my van's climate control?
- Thread starter MrPlow
- Start date
JHZR2
Staff member
But a lot of cars, at least foreign, do have an ac on or off button. Our 94 Previa, precursor to OP’s van, had separate control of AC and the other blower/temp/routing functions. As I recall, the recirc was a cable operator, and AC was not interlocked.
I haven’t looked at it closely, and it defaults to on, but our two Honda cars have an AC on/off button, as does my BMW. My Mercedes cars can control the AC through the temperature wheel. The BMW plays with airflow flaps constantly, including at shut down, which is annoying to me.
My 98 S-10 is like OP’s, when it’s set to blow on the windshield, you have no say.
My 96 Ram has an option to run the fan with or without AC for all flow conditions, by either turning the fan control right or left through the speed options. But it has no control of recirc that I’m aware of.
so many variants...
Nick1994
$100 site donor 2024
That’s how all cars are. You breathing in the car makes a surprising amount of humidity, and your windows might fog up and reduce visibility. You aren’t “using up” your a/c system. It’s good for it to be used and not sitting, the refrigerant isn’t going anywhere.
Tacomas and 4runners of that era have a wire behind the hvac control panel that can be disconnected. This disables the auto AC when set on defrost but the AC button will still work if needed. The other option involves modifying the notches behind the knob that allow the knob to go past the ac switch. I disconnected the wire on my last 2 tacomas and it works great. Not sure if this would apply to your van but it's worth a look. Not sure about the vent setting but it must be getting "tripped" by a notch behind the knob. The Toyota forums have a bunch of write-ups on this for the Tacomas/4runners.
If the few minutes the compressor is engaged is going to kill your a/c system, it was going to break down anyway.
Kind of a self own, no?
Every vehicle I've had did the same, but you could select recirc and A/C both off if you wanted. In this instance I think Toyota's thinking might be to give you the most efficient defrost since that's what you're asking for. (many people are too stupid to realize that's the best option.)
That said, if it's only taking a little warm air to keep the windshield clear, then it looks like the setting with defrost and some on your feet is the answer.
I agree with OP. On some early 2000 hondas I believe there was a way to accomplish this. I dont need the AC compressor engaging and disengaging 3 times a minute when I am running down the highway when its 40 degrees outside and just some nice hot air would do just fine. The real reason automakers have it set up the way they do is most people are too simple to understand how to operate a defroster.
On my XB, it only shuts off recirc and runs AC compressor if you go to full defrost, luckily I can keep it on recirc and have no AC operation if you select the Defrost/Lwr split.
On our Sienna anytime you have any amount of defrost air you have AC operation (unless of course if ambient temperature is too low for AC Low pressure switch to be satisfied)
I am quite capable of figuring out when I want AC compressor operation. I am quite capable of running AC periodically in winter during appropriate times to exercise the system.
On my XB, it only shuts off recirc and runs AC compressor if you go to full defrost, luckily I can keep it on recirc and have no AC operation if you select the Defrost/Lwr split.
On our Sienna anytime you have any amount of defrost air you have AC operation (unless of course if ambient temperature is too low for AC Low pressure switch to be satisfied)
I am quite capable of figuring out when I want AC compressor operation. I am quite capable of running AC periodically in winter during appropriate times to exercise the system.
And people wonder why after not using the A/C for 6 months over the winter, it doesn't work on the first warm day in spring. Seals shrunk and freon leaked out.
When you have to use defrost open a window about 1/5 of the way ( I open the passengers front if no one is in that seat, so I do not get a draft on me, and also it is a window easy to see so it reminds me to close it ), and this provides an exit vent for the cabin so much more air comes in the intake that the defrost is using. Just opening one window some will drastically improve the defrost action and the windows that are frosted up will clear up much much faster. This works like magic more than 90 percent of the time. Try it sometime, you will be surprised how and quick the defrost works when you crack open just one window.
OP, if you are concerned about running your AC to defrost using some gas, open a window some and the windows will defrost quicker, and you will be able to turn off the defrost ( and AC ) much sooner.
OP, if you are concerned about running your AC to defrost using some gas, open a window some and the windows will defrost quicker, and you will be able to turn off the defrost ( and AC ) much sooner.
I'm a bit confused as to why some of you think I plan on keeping the AC off all the time? Where did I mention this? 
I just want control over the AC operation. That's it. Nothing fancy. For regular driving around, a little warm air on low along the windshield keeps it from fogging up, even with the windows closed and recirc on. This is how it has been in every vehicle I have owned. My truck doesn't even have AC and it keeps the windows clear with just some warm air.
If I get in the car all wet and get it really foggy, I turn on the AC to help out.
And the AC being on in the morning when I need air on the windshield to melt frost, it just makes it take longer to heat up as it fights the heater core and engine temp.
And saying I should not mod it and keep it stock because Toyota knows best? Come on, dude. That's pretty obtuse isn't it?
I just want control over the AC operation. That's it. Nothing fancy. For regular driving around, a little warm air on low along the windshield keeps it from fogging up, even with the windows closed and recirc on. This is how it has been in every vehicle I have owned. My truck doesn't even have AC and it keeps the windows clear with just some warm air.
If I get in the car all wet and get it really foggy, I turn on the AC to help out.
And the AC being on in the morning when I need air on the windshield to melt frost, it just makes it take longer to heat up as it fights the heater core and engine temp.
And saying I should not mod it and keep it stock because Toyota knows best? Come on, dude. That's pretty obtuse isn't it?
Most people here feel you're trying to fix something that isn't broke. Saying, "it just makes it take longer to heat up as it fights the heater core" isn't true as most compressors don't kick in below 40F anyway, and if they did, the longer time to heat up is marginal. And saying, "I don't like the idea of wasting my AC system and gas when it is not needed" is also flawed as the amount of extra gas you use idling might be a few cents. If it really bothers you, put an on/off switch in the dash wired to the compressor so you can keep it off at will.And saying I should not mod it and keep it stock because Toyota knows best? Come on, dude. That's pretty obtuse isn't it?
Honestly I’d quit worrying about it. Most of my GM cars since the late 90’s-early 00’s, turn on the A/C compressor whenever I use the floorboard heat selection. Incidentally, I haven’t had an A/C system failure in decades. The compressor running is a good thing.
Wire a switch into the circuit for energizing the coil of the relay for the AC compressor clutch if you can find it, and mount the switch somewhere on the lower section of the dash.
If you can't find the AC clutch relay coil circuit, then wire a heavy duty switch in the wire to the AC clutch. Just be sure to use heavy stranded wire ( I think 10 gauge stranded will work for an AC clutch ) and a switch with a high enough current rating. High current low voltage switches are getting harder to find. You might try McMaster-Carr, but it has been a while since I bought any from them. They use to carry them, maybe they still do.
If you can't find the AC clutch relay coil circuit, then wire a heavy duty switch in the wire to the AC clutch. Just be sure to use heavy stranded wire ( I think 10 gauge stranded will work for an AC clutch ) and a switch with a high enough current rating. High current low voltage switches are getting harder to find. You might try McMaster-Carr, but it has been a while since I bought any from them. They use to carry them, maybe they still do.
I feel your pain with running the AC the time. Looks like you have manual controls like my Focus, so all I do is turn the vent choice knob to the defrost/feet and then sneak the vent setting back towards feet until the AC stays off but the defroster vent is still mostly open so it keeps the window clear. I suppose you may be able to adjust where the AC switch activates on the vent knob too, but I haven't bothered as my cheat seems to work fine.
Or if you can find the wire 5AAAF referred to wire a switch into that wire so you can disable or enable the AC with defrost as you wish.
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