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]

Hoses:
Chances are that anyone doing an A/C system will need all new hoses. The old lines are compatible with R12 only. They allow the R12 to "breathe" and will not work if you are using R134. New Barrier hoses must be used if using R134. Your local A/C shop will probably be your best bet when getting new hoses made. If making your own hoses make sure to use the correct fittings (flare, o-ring, etc.).

Some new charge port fittings


New Hose


The SD507 was made for o-ring fittings so I acquired some o-ring to flare adapters. I ended up not using these.






Receiver Drier:
The drier contains a desiccant that removes moisture from the system and it also stores extra refrigerant. This item is fairly cheap <$20 and should not be reused. There are a few options out there depending on where you want to mount it. You can find them in a variety of sizes and also ones for lying horizontally.

Original


The drier I plan to use. Its a "short" version. It also has ports for using pressure switches.






Wiring:
Below is a wiring diagram I found for the VPC System. I believe it was made by someone on this site (Thanks). The only change I’m going to add is the addition of a trinary switch on the drier. The trinary switch will cut off the compressor if the pressure is too low or too high and it will also engage the condenser fan after the pressure reaches a certain point.