AC installation

[1337l33t]

Help me figure it out, I'm assembling an AC on a Previa without AC .
So far I've only been able to find and buy tubes, an evaporator and a compressor. All that's left to buy is a radiator with a dehydrator and a pressure sensor.

I don't understand anything about this, I only seem to understand by trial and error where to connect the radiator, evaporator, and compressor. For clarity, I've drawn on a photo of my tubes what I don't understand.



1) Did I distribute all the connections correctly in the photo?
2) What a part number of pressure sensor?
3) Is it necessary to increase engine revolutions +200rpm when the AC clutch is engaged? What are the consequences if this is not done?

[John Kaufmann]

Help me figure it out, I'm assembling an AC on a Previa without AC .
So far I've only been able to find and buy tubes, an evaporator and a compressor. All that's left to buy is a radiator with a dehydrator and a pressure sensor.
I'm guessing you may know that your "radiator" (called a "condenser" in North America) is not the radiator used for engine and transmission cooling, but mounts in front of that radiator -- and likewise your "dehydrator" (called a "dryer" or "drier" in North America) mounts in front of that condenser. Your English is very good, and you seem mechanically adept, so I suspect you are just thinking functionally, but I want to make sure there is no confusion.


I don't understand anything about this, I only seem to understand by trial and error where to connect the radiator, evaporator, and compressor. For clarity, I've drawn on a photo of my tubes what I don't understand.

1) Did I distribute all the connections correctly in the photo?
2) What a part number of pressure sensor?
For questions like those, do you know about ToyoDIY? - all parts, with illustrations. If you don't have an account, you can send me your email in a PM, and I'll send the account invitation.


3) Is it necessary to increase engine revoluutions +200rpm when the AC clutch is engaged? What are the consequences if this is not done?
Yes. That is managed by the control unit (called an "AC amplifier" in North America), which is also needed for all other AC functions.

[1337l33t]

I'm guessing you may know that your "radiator" (called a "condenser" in North America) is not the radiator used for engine and transmission cooling, but mounts in front of that radiator -- and likewise your "dehydrator" (called a "dryer" or "drier" in North America) mounts in front of that condenser.
Yes, I know that.


For questions like those, do you know about ToyoDIY? - all parts, with illustrations. If you don't have an account, you can send me your email in a PM, and I'll send the account invitation.
I don't know about it, but I'm not sure it will help me. I found illustration, but I can't quite figure out the actual layout of the tubes. Do I at least have all the tubes now? Or are there currently ones that are missing?



Yes. That is managed by the control unit (called an "AC amplifier" in North America), which is also needed for all other AC functions.
I'm still not sure if it's necessary to use this? Why not just engage the clutch without boosting engine RPM?

[1337l33t]

I think this tube is missing

[John Kaufmann]

... I'm not sure [ToyoDIY] will help me. I found illustration, but I can't quite figure out the actual layout of the tubes. Do I at least have all the tubes now? Or are there currently ones that are missing?
That is precisely the kind of question for which I would consult ToyoDIY -- and the illustration in your post looks like it came from there, because ToyoDIY gives you most of the same pictures your Toyota parts counter person would have -- and note that the illustration you found showed you a section of tube that you are missing.

What year and model code is your Previa?


I'm still not sure if it's necessary to use this [AC Amplifier]? Why not just engage the clutch without boosting engine RPM?
Of course engaging the compressor clutch will load the engine. At a minimum, at idle that loading is likely to kill the engine. I agree that in principle you should be able to operate the clutch and compensate manually -- but I would not want to do it.

[Jan-Willem]

I'm still not sure if it's necessary to use this? Why not just engage the clutch without boosting engine RPM?
I don't think, boosting the rpm is an absolute requirement. If the engine is warmed up... as long as it doesn't stall.. and you can always increase the idle a bit. But I think you still need some control logic to cycle the compressor. it should cycle based on the temperature measured at the evaporator(s). Unless you have a variable displacement compressor(which have use even more control logic), it should turn on, and off all the time. It probably depends on outside air temperature and such, but on the cars I owned it is runs maybe 1/3 of the time or so, maybe half a minute on, then a minute off, then half a minute on, and so on...
You can look at the components of aftermarket ac kits, what parts are used, for example:
https://www.classicautoair.com/?srsltid=AfmBOopCbeblO8IFTTc5PxnHEUXvFCBuJZvZUTbq-CpBAIwme-rumeIc
I wanted to build in AC in a classic car, as a project, a learning experience, but I haven't gotten around to it, and both cars I had, that were good candidates, I don't have anymore :(