[AROWHED]

I stripped the entire AC system out of a junk 2009 Toyota RAV4, with the intentions of making it work in my 65 GP (which has a serp belt system already) since it is small, designed for R134a, lightweight and parts are readily available thru Rockauto and cheap. What I did not realize however was the compressor is a variable displacement model (clutchless) and is controlled by vehicle computer via a Compressor Control Valve. Is there ANY way to make these variable compressor systems work once removed from factory vehicle? I would bet a small control circuit could be constructed that monitors interior temperature, the high side pressure switch, and maybe even engine RPM, but finding the parameters to design such a circuit by is eluding me.
https://www.rockauto.com/en/catalog/...rol+valve,6640

[Stuart]

I looked online and it appears the control module for the a/c in a Rav 4 is a separate module that's not part of the main computer, would it be possible to make it work by itself? I found some wiring diagrams at https://www.2carpros.com/questions/ac-30700587 but didn't spend much time examining them.

[AROWHED]

I waded through this for an hour and it seems the AC Amplifer, whatever that is, still works with the main vehicle PCM. I just searched this for anywhere "A/C" shows up. Still clear as mud. https://drive.google.com/file/d/19Tx...4oCRnn0cJ/view

[hgerhardt]

I'm using a compressor just like that in my homebuilt airplane. The compressor needs a 12V PWM-controlled power source at ~400 Hz. I used an Arduino as the PWM source and an automotive-rated MOSFET motor controller to supply the 3A or so needed.

I figured this all out by connecting an oscilloscope to the compressor in my mom's 2009 Corolla and running the A/C in various modes.

If you know enough about electronics to properly solder wires and understand basic circuitry, I'll help you with needed parts. Otherwise, you probably ought to find a different compressor.

Below is a photo of the PCB I designed and assembled. The 2nd MOSFET controls the blower (20A goes thru that thing without a heat sink). You can get the p/n's of the components by looking at the photo carefully.

[BB70]

Originally Posted by hgerhardt

I'm using a compressor just like that in my homebuilt airplane. The compressor needs a 12V PWM-controlled power source at ~400 Hz. I used an Arduino as the PWM source and an automotive-rated MOSFET motor controller to supply the 3A or so needed.

I figured this all out by connecting an oscilloscope to the compressor in my mom's 2009 Corolla and running the A/C in various modes.

If you know enough about electronics to properly solder wires and understand basic circuitry, I'll help you with needed parts. Otherwise, you probably ought to find a different compressor.

Below is a photo of the PCB I designed and assembled. The 2nd MOSFET controls the blower (20A goes thru that thing without a heat sink). You can get the p/n's of the components by looking at the photo carefully.

Nice job there !!

[AROWHED]

VERY, very impressive. Created your own control circuit, my hat is off to you, sir. I'm a career PCB designer and have to say, that is one well organized and clean layout. And for an aircraft?? Wow. What software did you use? Would you be willing to share the schematic and design files? What inputs does it require?

[hgerhardt]

Originally Posted by AROWHED

VERY, very impressive. Created your own control circuit, my hat is off to you, sir. I'm a career PCB designer and have to say, that is one well organized and clean layout. And for an aircraft?? Wow. What software did you use? Would you be willing to share the schematic and design files? What inputs does it require?

Thanks! I used Eagle to lay out the PCB. This is the first time I've ever attempted to design a PCB, and the first time I've ever done SMT devices. It's a 2-layer PCB with all the components on the top side. Used a 1/4" thick aluminum plate on my gas stove to solder all the SMT components at once. Amazing how well that works!

An Arduino does ~400Hz natively, so that works great for generating the PWM for the compressor. Also happens to work great to control blower speed. Another thing I had to learn was coding (Arduino-specific C++, pretty easy) to make all this work! The Arduino also operates air diverter valves, turns on an LED to indicate compressor "on", and sends hi-side pressure and evap temp to the EFIS on the airplane to monitor performance in real-time.

Sensor-wise I have a GM hi-side pressure transducer and a generic 100k thermistor for evap outlet air temp. Those sensors are all you need. The code runs the compressor either wide open or throttles it down based on evap temp and condenser pressure.

Send me your email via PM and I'll send you the Eagle files (or a pdf if you don't have Eagle) and the Arduino code and a parts list.