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Cheapo Ac Questions


dj paul

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Hey guys, ive been reading up on AC and it actually looks pretty easy if you can find all the correct hoses and such. What i was thinking about doing, was taking the evaporator assembly out of a mitsubishi 3000gt. it has the controls and everything with it and can be easy modded to fit in current dash. i found an expansion valve out of a 280ZX a drier assembly out of a nissan stanza (bout size of coke can), compressor off of old datsun 210 or something. (it was an L series motor), and a condensor off of i dont know what yet. ive read about a guy rigging ac up in his car but i dont know what parts he used. seems like he had a lot of trouble since he got stuff from junk yard. This is all new stuff so i would have to flush out old refrigerant (since it solidifies when mixed with new) and i already have vent hoses and such and the entire dash is out right now. im just wondering is this as easy as i think? would basically all i have to do is hook this stuff up to the 3000gt "climate control"?

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HI

A/C is not rocket science, and as long as you have a compressor, reasonable sized evaporator and condenser, T/X valve hoses, thermostat, fan, wiring, Etc. The principal is very simple compress the refrigerant into a liquid against the T/X valve and create a gas in a vacuum on the other side in the evaporator, and the you have A/C of course this is a simplification.

So there is no need to use all the parts from the same car/manufacturer! so in answer to your question, YES you CAN build your own A/C.

 

Remember you MUST have air flow across both the Evaporator and the Condenser while the compressor is running or the evaporator will freeze solid (thermostat also controls freezing) and the head pressure will quickly climb too high and blow the high pressure hose or worse!

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ok cool man, thanks. from what i said does that sound like a decent setup? ive been reading about this so i know some lines have to be able to expand a little and some have to be hard so they keep a constant pressure. any tips on where to get the lines for this that refrigerant wont leak thru?

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I think your going into uncharted territory here. I'm not saying it can't be done, but no one on this site probably has finished an install. If I were you, try calling some of the A/C companies , like vintage air or southern cool ,and get some of input from them. I do think that 2 members here, Bartman for one, are trying to put a/c in their cars as well. But i don't see any reason why it wouldn't work. I'll down load some diagrams from my vintage air system, that would help you in the hose routing.

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sure, thankyou. like i mentioned up there, i have seen one succesful install but he was using junkyard parts that had the old refrigerant in it and didnt have everything out of his car like i do now, including the dash. i did not even know how the hell ac worked untill i saw these http://autorepair.about.com/od/generalinfo/l/bldef020.htm

http://www.diynetwork.com/diy/ab_auto_air_conditioning/0,2020,DIY_13674,00.html

now from what im reading there are two types of systems, an expansion system and and something else that wasnt used as much. supposedly as long as you stay with components from only one of these systems then you should be ok. also, from what im reading, the hardest part is routing the stuff through the dashboard and all that, which my dashboard is in my basement right now! the hose systems and all that crap would be greatly appreciated though. i hate the extra weight that it adds but everytime my friend stops he has to open up the door and wave it around because its so hot in there. and plus this thing would only cost about $50 max because ive found a bunch of surplus new parts from older cars and newer cars.

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I used to fit custom one off A/C into many Euro cars and most of the rigid lines were made from copper or aluminum tube with rubber A/C hoses using aluminum ends swaged on. But you can use rubber for all of them if you need to. If you can find a Refrigerant/A/C wholesaler they have pre-made aluminum lines of various lengths they can make your flexible rubber hoses to order and have other bits you will need (Receiver drier, thermostat etc.) most newer cars have electronic type thermostats so depending on your skill level you can use some type of factory temp/climate control if you wanted to.

 

If you feel comfortable putting al the bits together Go for IT, that's what our hobby it all about! After all if you wanted an easy A/C car you could just go out and buy one, but what would be the fun in that? Again its not rocket science.

 

Also with the "NEW"? R134 you need less gas than R12, you used to slowly fill the system until the sight glass was clear (no bubbles) but with R134 you need to charge it to the pressures on the gauges.

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right, oh and actually all this surplus stuff is on ebay. compressor -$10 condenser-$20 other stuff was like 5 and 10 bucks. honda and saab stuff looked pretty decent to use. i couldnt find this out, but isnt the thermostat usually on the evaporator assembly? since it has the controls and crap already on it?

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HI Again,

What evaporator are you going to use? Do you have a picture? Does the evaporator have the heater as well? This would make the install less painful, and more useful then the original, the main fault with the genuine 240~280z A/C is the location of the evaporator (just behind the dash), and you cant mix warm air from the heater, or direct the A/C to the windshield for de misting (better that heat).

 

Were you intending on adapting your original controls? As they didn't have an adjustable thermostat fitted!

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for some reason i cant get the picture to post up right. but it has the controls for heat, defrost, cool and different fan levels. so its the actual whole assembly that does everything. im gonna ask the guy if i can get more pictures but it looks like it would work well.

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Is this the type you are looking at? I found a pic of a 3000gt on ebay

It is a blow through type and fits between the fan and the heater unit, it is probably the easiest to fit, but you will lose the glove box (that's where it fits, against the firewall behind the glove box area) but this will allow you to use all the std 240z controls! all you need to add is the thermostat.

 

 

 

9d_1_b.JPG

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Hi

You will need to measure the distance between the Fan and the main Heater unit (it may be to small to fit this unit into) I cant remember how much room you have to play with .

You remove the bellows and the evaporator fits in the gap, you will have to make adaptors for the fan and the heater box of course, you should also fir a fan with more air flow. you may also be able to move the fan over to give you more room.

 

 

 

So you will need to measure the space you have to play with and get the measurements of the unit you want to fit. You may find a thinner unit would suit you better so first find out how much space you have OK.

 

heater1.jpg

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is that a picture of our evaporators? if it is i pulled one out of my car. i was thinking it was the blower motor or something which now that i think about it is a part of the assembly itself. i never had this car working when i got it so i didnt know what the hell it was. so i could just buy the other stuff and be ok?

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With modern A/C you have a few compents that the old stuff didnt have.

 

New stuff has a pressure sensor on the high side to make sure the pressure doesnt get too high and blow a hose. New stuff has a temp sensor stuck in the fins on the evaporator so that can tell the computer to shut off the compressor if the evaporator temp drops below a specific temp, usually close to freezing. This way the evaporator doesnt freeze up on the outside due to condensation forming on it from the temp change. New stuff also tells the PCM to bump the idle up when the A/C is on and to turn the radiator fan even if the engine is cold.

 

I dont know what you have for an engine in your car but if I personally was going to install A/C in my LT1 powered 280ZX, I would use the PCM to control the compressor and idle. I think you could get away with a pressure switch that would turn off the compressor once the high side pressure got to a certain PSI. I dont know how you would stop the evaporator from freezing up though. Maybe someone makes a temp sensor switch that you could use in the same way as the pressure switch?

 

Guy

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