Doug's A/C System, R&D/Build Thread Options

[dlee6204]

I thought I would document my A/C adventure in the hopes that it would be a good reference for anyone else considering A/C. I’ll first touch base on the stock system and on custom options and then start building my own system to start testing on. I’ve working on a few systems before but I'm sure there is someone that knows more than me so don't be shy sharing or adding anything. (IMG:style_emoticons/default/smile.gif)


To begin things off here is one of the better overviews of an A/C system. Follow the link and you can see a breakdown of the whole system.


http://www.movacs.com/How%20it%20works/index.html





Anytime I refer to the stock system I will be referring to the dealer installed VPC system mostly because the only A/C cars I had came with this system and I have plenty of parts around.

I also borrowed some photos off this site so if I used any of yours... Thanks. (IMG:style_emoticons/default/smile.gif)


Compressor:

The compressor that came on dealer installed A/C systems was a York Piston style compressor that had a capacity of 6 cubic inches/Rev. From what I could find it used about 7-10 horsepower from the engine. You can still use this compressor however there are better, more efficient options out there. When choosing a new compressor it is a good idea to find one with a similar capacity. In this case going bigger does not mean better. An A/C system works as a whole unit and if you dramatically change one aspect of it, you will likely see negatives effects elsewhere. Choosing a compressor that’s too big will overwork the system, yielding no little to no benefit, and create a not-as-efficient system. During my search I looked mostly at Sanden style compressors so that's what I'll be referring to in my build. Using a modern compressor like the Sanden will only use about 3-4 hp from the engine. I have heard quite a few people use the Sanden 508 compressor with good results. It has an approximate displacement of 8 cubic inches/rev, which IMO is slightly more than I'd like to make a jump to. I'm not saying it wouldn't work, it obviously works, however I think I will get slightly better results and pressures using the Sanden 507 (approx. 7 cubic inches/rev). The SD507 is also slightly smaller in size than the 508.

Here is a picture of the York Compressor


A side by side with the SD507





And here is a SD508

[dlee6204]

Compressor Mounting:
This is probably the biggest obstacle when deciding to go with A/C. The dealer installed the York compressor on the passenger side of the motor. In order for it to fit they had to cut both the engine shelf and the engine tin and in most cases, it looks like they did it with a hacksaw.... while blindfolded. The two disadvantages with this is that it no longer leaves the engine bay sealed and it’s also an ugly installation. The compressor was run via a belt and pulley that was installed behind the engine cooling fan. An idler pulley was also used. With the size of modern compressors, it leaves multiple potential locations to mount a new compressor.

Stock Location- There are many Sanden-to-York bracket adapters out there that would allow you to mount the new compressor in the stock location using the stock york mounting bracket. In some cases, depending on what compressor and adapter you use, you are able to install the compressor without cutting the engine shelf. The engine tin still needs to be cut though.

[If anyone has detailed pictures of a mounted York compressor, please share. (IMG:style_emoticons/default/smile.gif)]
Here is the mount for the York.


Here are some photos of SD508s mounted on the side.



And a SD507 mounted on the side.


Top of the motor- Another place for installation is the top of the motor utilizing a pulley mounted to the front of the engine. In some rare cases I have seen the York compressor originally mounted on top of the engine which meant no need to cut the engine tin. IIRC 912's also did it this way too. Zambezi on this site is the only person I know who has successfully mounted a Sanden compressor on the top using a custom mount. He also used an offset pulley on the front of the fan to drive the compressor. Some pictures can be seen below. *If anyone is interested in an “offset” pulley, contact me. I’ve been working on something similar that would work. * I plan to mount my compressor on top using a smog pulley assembly to drive it. The smog pulley may or may not hold up to the abuse of driving a compressor… we shall see.

Here is a 912 setup


Zambezi's setup





Under the motor- This is another option I have been playing with. I believe that one could mount the compressor on the passenger side of the motor UNDERNEATH the engine tin, similar location to that originally. I believe you would lose your heat on that side but it could still be done without cutting any tin.