In an attempt to maximize my MPG, I want to install a small neon lamp on my dash to let me know when my AC clutch is engaged. Then, when on the interstate I can adjust my temp dial so the compressor doesn't run all the time and still stay relatively comfortable.
I installed one tapping into the red wire from the clutch wire that goes to the radiator cooling fans, but it only works when the fans are operating....so I don't have it wired correctly. I don't have a wiring diagram and am not sure if I need to place the indicator lamp wire on the AC Compressor relay in the under hood fuse box, or if there is a relay I can tap in to.
I did this on a previous vehicle, and it worked great.
Anyone got any ideas??

 

there is a single power wire that goes to the compressor clutch.

 

Hondadude,
Thanks for the reply. Yes, I know about the single power wire going to the AC clutch.
What attaches to that wire by way of a plastic connectoris a red wire that goes to the cooling fans for the radiator. So, when I tap into that wire, I'm also tapping into the power wire for the AC clutch.
I'm wondering if I can actually cause the AC compressor to turn off by dialing the temperature **** towards the red zone on the dial, or whether the compressor will stay on? There is no climate control....only the **** where you select the temperature range.
This should be do-able, right?
How about it guys?

 

I've got a '98 EX without automatic climate control - same as yours??

Turning the temperature dial towards warm doesn't directly control the compressor cycling. That's controlled by the evaporator temperature & it'll run whenever it needs to keep the evaporator temperature at it's setpoint.

When you turn the temperature dial, you're activating the heater, and moving airmixing dampers. But ALL the air goes thru the evaporator core, so I thinkthe AC should continue to run the same duty cycle.

If you want to run the AC but use it as little as possible, I think you should try this... Set the temperature all the way cold. Set the fan to 1 (fan off disengages the AC). Close the vent doors in the dashboard as much as you can so the actual air flow is minimized. As much as you can tolerate for temperature...

This may not give you as much fresh air exchange as you'd like, so use your judgement.

 

Jim,
Thanks for the tip. It makes sense.
The other car I did it with was configured differently. I found out today that what I was attempting did not work.
My question to you is: how will putting the control on cold, fan on "1", mostly closing the dash vents? Is it because of the air temp in the evaporator?
Thanks again.....Poppa

 

To do what you want to; you'd need a potentiometer in parallel with the thermistor that goes into the Evap core case; because that is what senses the actual A/C temp.

 

Yeah, by doing that you'd make the ECU believe that the evaporator core is cooler than it really is. This would make your AC less effective at de-humidifying the air, so it might feel damp inside the car.

It sounds like you'd want an under-sized AC unit. Less cooling power, &less power sucked away from the engine. You can't easily make your AC behave like that.

 

Hondadude,
Thanks. The next logical question is what value in Ohms do I want to use, or where can I find a spec on this?
thanks!

 

Doing this will minimize the air flowing through the evaporator. That's one way to make the evaporator stay cold longer, so it doesn't call for the compressor clutch.

Adjusting the temperature dial won't do that. All the air goes thru the evaporator, regardless of whether the heat is turned up.