Do you have a wiring diagram for compressor in Fabia 1.4 2003 AME 8V OHV and explaining how it goes on and off and the way it operates will be appreciated.

Does it have a 12V clutch as normal compressor or it needs other signals for control.simply I need to wire it to Local A/C system in my car.

No clutch on the compressor. It's controlled by the control unit via a duty cycled solenoid in the compressor. A pressure switch overrides the system in the event of high/low pressure. Inputs from the ambient temp sensor and evaporator temp sensor will also deactivate the system.

No clutch on the compressor. It's controlled by the control unit via a duty cycled solenoid in the compressor. A pressure switch overrides the system in the event of high/low pressure. Inputs from the ambient temp sensor and evaporator temp sensor will also deactivate the system.

Would you please explain more.

In my locally done A/C there is the following control:

12V supply to the clutch with a switch inside the car (they used the same one for internal blower) so both on at a time.

A pressure switch for high or low pressure is installed and when it is activated it cuts the 12V going to the clutch to protect compressor.

Now I need to install the original denso one in this system.My question is how to bypass the denso control and use the control I have or it is impossible without the original control.

I know about electronic circuits and I can do some extra work just let me know more details about this control.thanks for help.

It would be impossible without the control unit.

Is there anybody to share his knowledge about this denso compressor control.I believe it can be replaced with a simple control If more details shared about it.

Waiting for another advice.

If you don't mind waiting for me to find the time, I can 'scope the signal to the compressor and tell you what voltage and frequency it works with.

Trying to generate the necessary signal to make it do something is probably fairly straightforward, getting it to work in a controlled, safe manner will be a much bigger challenge, probably. 

 

Remind me by PM if you don't hear anything in a few weeks.

I'm 99% sure it's a duty cycled 5v to the solenoid.

If it is a duty cycle 5V is there any waveform for it.it is very easy to generate this by IC timer 555 and can use power transistor as a driver for this signal or control a relay but just tell me how it should be exactly.

I need to know exactly the on and off time and amplitude 5V or 12V or whatever?

Edited 27 March, 201610 yr by amosalamy

What will you set it to? Full load amplitude?

If you don't mind waiting for me to find the time, I can 'scope the signal to the compressor and tell you what voltage and frequency it works with.

Trying to generate the necessary signal to make it do something is probably fairly straightforward, getting it to work in a controlled, safe manner will be a much bigger challenge, probably. 

 

Remind me by PM if you don't hear anything in a few weeks.

A time domain signal showing amplitude and timing (typical scope signal) will be perfect.

I can simulate it and if you know the max working temp for the denso I can also stick a temp switch or sensor to shut it off if it exceeds that temp.

Yep, can do.

I would guess that the compressor has built-in 'safe operating area' protection, somehow. According to some info I just found, the compressor is designated 6 SEU 12C.

Not sure whether google can tell you anything about their operation.

What will you set it to? Full load amplitude?

Once I know the signal shape timing and amplitude I can generate an average one to keep it running and once the internal coil inside the car reaches the determined thermostat temp.you turn it off for a brake and on again once the temp goes higher 2 or three degrees more.

I know its efficiency will never be as original control unless I know how the original is and make a copy of it.

Yep, can do.

I would guess that the compressor has built-in 'safe operating area' protection, somehow. According to some info I just found, the compressor is designated 6 SEU 12C.

Not sure whether google can tell you anything about their operation.

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Now I know the variable displacement compressor solenoid valve is 10 ohm resistance and 12v to activate it that means it needs about 1.2 A current from the control circuit so now correct me if I am wrong

I need a circuit to generate duty cycle that has an output of 12v and can supply more than 1.2 A to the load(solenoid valve) and with adjustable on and off time.to get the A/C working

I have one question now?

Does it need to be synchronized with any other signal in the car or a free running one will be OK.

Good detective work.

 

I can't imagine that it needs to be synchronised to anything else, but the frequency of the PWM waveform probably should be similar to what the factory system uses, which is the remaining thing that a 'scope measurement should tell us.

 

The only thing I can add right now is that pin 2 of the solenoid connector is 0V, pin 1 is the PWM signal from the A/C control module. You probably worked that out already though.

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Thanks for all of you,I got this info and this is more than enough to do the job.

Special thanks to Wino for help.

Good work. Please keep us informed about your progress.

http://www.daycounter.com/Calculators/NE555-Calculator.phtml

This link to show how to build a duty cycle timer 555 and calculating the values to drive the solenoid valve for 90% or 50% duty cycle.

A power transistor like 2N3055 should be added to the o/p stage to drive the solenoid current.when finished and working I will add the complete circuit.