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New to ev air con questions

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I have been converting a capri into an ev and the car came shell only, if i wanted to run a donor ac-climate control syst, from a duel climate car like the nissan altima 2014, the system is set up utilising the cars canbus etc as far as i can tell from the system schematic certain parts of the ac amplifier control module report to other ecus in the car, can i run the system independently if i get all the right components and have the climate system indepent of other car functions. Or will it not work as it will want can signals from else where. Im pretty new to canbus stuff but wanting a more modern feel to my aircon, sorry if this is stupid question new to forum and early days in my conversion but like getting my head around the tasks at hand first.

Thanks in advance
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Unless anyone has specific experience, I would say, the only way to find out is to try it in a working vehicle.

You could start unplugging the modules it might talk to, one by one until it stops working - whatever remains is what you need.

A better approach is to intercept the CAN messages where they go into (and out of) the Climate control. You might be able to decode them (with the help of one of the CAN Sniffing apps) - but mostly that's near impossible.

An approach that seems to work is to cut the can wires where they go in to the climate control. Then you need to buy / build a CAN Bridge. connect one port on the bridge to the climate ecu and the other to the rest of the vehicle. Initially it just passes all the data in both directions, as if the bridge is not there (transparent).

Then you can start blocking individual messages (in software) to see what happens - eventually boiling it down to the messages it actually needs. You may be able to spoof these using software running on the bridge itself, or another module which just spits out appropriate messages.

An example might be that it needs the engine running before it engages. This could be in the form of reading the current RPM (as a CAN message). Then it would be a case of sending a message repeatedly, telling it the engine is running at a certain RPM.

I had to go through this process of discovery to get the Power Steering to work. It switches on when the Engine is reporting over 800rpm.
 

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Ford capri 1974
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Discussion Starter · #3 ·
Unless anyone has specific experience, I would say, the only way to find out is to try it in a working vehicle.

You could start unplugging the modules it might talk to, one by one until it stops working - whatever remains is what you need.

A better approach is to intercept the CAN messages where they go into (and out of) the Climate control. You might be able to decode them (with the help of one of the CAN Sniffing apps) - but mostly that's near impossible.

An approach that seems to work is to cut the can wires where they go in to the climate control. Then you need to buy / build a CAN Bridge. connect one port on the bridge to the climate ecu and the other to the rest of the vehicle. Initially it just passes all the data in both directions, as if the bridge is not there (transparent).

Then you can start blocking individual messages (in software) to see what happens - eventually boiling it down to the messages it actually needs. You may be able to spoof these using software running on the bridge itself, or another module which just spits out appropriate messages.

An example might be that it needs the engine running before it engages. This could be in the form of reading the current RPM (as a CAN message). Then it would be a case of sending a message repeatedly, telling it the engine is running at a certain RPM.

I had to go through this process of discovery to get the Power Steering to work. It switches on when the Engine is reporting over 800rpm.
Awesome thank you, i will do some research and learning on can bridges and see what i can learn :) fingers crossed
 

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Ford capri 1974
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Discussion Starter · #5 ·
This is how I've done it:
Im not really sure what or how i would use such a board and what software to run it. Atm but looks cool and would be great if i could use it. But pretty novice when it comes to this stuff
 

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Ford capri 1974
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Discussion Starter · #6 ·
This is how I've done it:
Any help is appreciated on how to run through the comands and how to decifer the can bus messages and where i can get the neccessary software, to be able to keep the needed can message to run the a/c please. I dont mind learning. Will probably be pillaging a lot from the altima as will need door locks window actuators probably even the steering colum and rack so far i have a shell and some parts that are probably useless and will get a donnor car, so definitly will need how to take the right can messages and translate so i can use them, i dont even understand how this device works, does it allow you to read the messages or will replicate them......replace etc etc sorry hahaha brave new world
 

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I would do some reading / watch some videos about CANBUS so that you understand the essence of how it works, what it's for and how it's implemented in vehicles.

From there, there are two approaches.
There's lots of CAN Sniffing applications out there. Some are free, others paid. I've not used any, so I can't advise on what's best / most useful. If you've never written any code before, this is probably the best place to start.

My approach was to write a couple of quick programs to run on an arduino which just filter the data.
The most useful keeps a record of all the types of message received. If a message has been received more than say 10 times, it ignores it - only displaying the infrequent messages.
After a few mins, it displays nothing - i.e. it knows about all the background housekeeping messages.
Then, you switch something on - say, like pulling the park brake lever. One or two new messages it has not seen before will pop up! You know that these contain the message 'someone has engaged the park brake'.
Release the brake and you get an other message or two. Look at what bytes have changed between applying & releasing - and you have the code for the park brake.

The same approach could work for AC too.

Once you have some codes / messages - try injecting them in to the CANBUS to see if you can switch the AC on & off, for example.

Unfortunately, it's not a quick process - a lot of experimentation!

It's worth searching the web to see if anyone else has decoded any of the messages for that vehicle or even that manufacturer. At least that gives you a starting point.
 

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Ford capri 1974
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Discussion Starter · #8 ·
I would do some reading / watch some videos about CANBUS so that you understand the essence of how it works, what it's for and how it's implemented in vehicles.

From there, there are two approaches.
There's lots of CAN Sniffing applications out there. Some are free, others paid. I've not used any, so I can't advise on what's best / most useful. If you've never written any code before, this is probably the best place to start.

My approach was to write a couple of quick programs to run on an arduino which just filter the data.
The most useful keeps a record of all the types of message received. If a message has been received more than say 10 times, it ignores it - only displaying the infrequent messages.
After a few mins, it displays nothing - i.e. it knows about all the background housekeeping messages.
Then, you switch something on - say, like pulling the park brake lever. One or two new messages it has not seen before will pop up! You know that these contain the message 'someone has engaged the park brake'.
Release the brake and you get an other message or two. Look at what bytes have changed between applying & releasing - and you have the code for the park brake.

The same approach could work for AC too.

Once you have some codes / messages - try injecting them in to the CANBUS to see if you can switch the AC on & off, for example.

Unfortunately, it's not a quick process - a lot of experimentation!

It's worth searching the web to see if anyone else has decoded any of the messages for that vehicle or even that manufacturer. At least that gives you a starting point.
You make it sound surprisingly simple, but thank you. I will get to learning. I understand what can is for and the basics but lack indepth knowledge have studyed basic binary systems before but that info is in a fog in my head unfortunately im sure it will come back later, thanks for all the advice :) you are a star :)
 
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