Bit of A/C tech

[chimpboy]

I am a total n00b with auto A/C but I am trying to transplant a complete air con system from one vehicle to another, and I have a few wires I am not sure what to do with.

Firstly, there are two wires and a fitting next to the receiver dryer. I am thinking this is some kind of pressure sensor and that the two wires should break the circuit when there's over pressure, hence these two wires should just go in series with the switch/compressor wiring? Would this be right?

Secondly, there is some kind of sensor stuck through the evaporator which also has two wires sticking out of it; I would assume this to be an ice sensor but again, I am not sure. Would this be the same deal, wired in series with the switch/compressor so that the compressor gets switched off if the system ices up? This one looks like it might be connected with a copper capillary to some part of the a/c gas circuit as well but I don't want to dismantle this stuff too much.

The A/C gear is out of a Suzuki Barina.

Anyone know?

Also my plan is to basically hook all the a/c stuff up exactly as it was in the barina, no changes at all, just new o-rings and seals everywhere, then in theory I should just be able to get an A/C dude to gas it up. Would that be right or do I need to watch out for something else? I think I will probably need a new receiver-dryer from what I've read as they are a bit disposable.

Jason

[Gribble]

The reciever/dryer switch is a pressure switch. It actually senses if there isnt enough pressure in the system. Usually this is wired in line with the magnetic clutch wiring on the compressor.

The second one sounds like your thermoexpansion valve. Its also generally in-line with your clutch. This is what makes your a/c cycle so it doesnt freeze.

Dont take this as gospel, its a while since i did a/c at tafe.

[chimpboy]

Thanks Gribble, that confirms my guesses...

I've got the evaporator (and my radiator) having some slight mods to outlet positions today. Hope the engine still stays cool when the fan's got an evaporator as well as a radiator to contend with.

Anyone else got some knowledge to share, to confirm or deny that I should just wire both of these sensors in series?

[me3@neuralfibre.com]

Sometimes these aren't rated for current and have a relay to switch the compressor. The pressure switch is generally a binary High / Low pressure switch - cuts out in either situation.
Generally it's also setup to not run unless the interior fan is on.
Electric fans move nowhere near the air of the engine fan, provided it's all in good nic. The electric fans are mostly for sitting in traffic with engine idling.

Paul

[cooter]

plumb it all up mate and replace the receiver drier the wiring is like gribble said but yeah i would use a relay for the comp clutch
and makesure the evaporator is sealed in the heater box or it will not be efficient
dont be afraid to gas it with lpg it is cold freakin cold shame you are not up this way i just aquired a revovery station

[chimpboy]

Cool thanks. Yep I was planning to use a relay for the compressor clutch.

Can you really gas these things with LPG? I don't think I'm game to anyway to be honest, rather get it gassed and leak-tested by a pro.

[cooter]

i have gassed heaps of our trucks with lp works well r290 is its refrigerants code
they are mixing it with butane for use in factory car aircon systems in the states as it is zero ozone depleting and as efficient as r600 and r12

[Gribble]

Yeh forgot to mention that. T off a wire from the fan switch, via the a/c switch via the tx via the pressure to a relay that switches the clutch.

Also look out for an idle-up of some description, being jap its probably an air bypass valve. Run that parellel to the clutch fan (if its electric).

[Gribble]

i have gassed heaps of our trucks with lp works well r290 is its refrigerants code
they are mixing it with butane for use in factory car aircon systems in the states as it is zero ozone depleting and as efficient as r600 and r12

Ive heard about people doing this but is it legal here though? Considering how strict the authorities are on LPG fuel systems I cant imagine LPG being legal in your a/c system, especially with fittings in the cabin space.

[cooter]

yep legal as it is a refrigerant

[Mousie]

i`m a fridgey... and i would never use lpg..
why use a flamable refrigerent......
when there is one perfically designed for automotive use...

but.. it is up to you...just becarfull you dotn blow up

[chimpboy]

I'm just going to get an a/c expert to gas mine up if I can ever farking get it all hooked up

But anyway, it is pretty interesting.


I found this: "R290 is pure propane, a hydrocarbon and efficient naturally occurring refrigerant with similar properties to R22. No ozone depletion potential and an extremely low global warming potential. Environmentally safe but highly flammable. Used only after careful consideration to safety
ODP = 0 and GWP = 3."

There's also this from BOC gases:

"CARE 30 (blend of R290 and R600a propane and isobutane) is a hydrocarbon blend ideal for replacing R12 and R134a in systems like drinks dispensers and bottle coolers in pubs."

Most Aussie LPG would, presumably, be a dead ringer for CARE 30.

Personally I don't want to have insurance hassles on the slim chance that my a/c system starts a fire so I am not going to do it, but it does sound like it's pretty viable if that's your thing. I guess in theory it's not really any more dangerous than having an LPG system in the car anyway, and probably less dangerous than having a petrol tank.

Anyway, just thought it was interesting info that I'm not personally gonna use!

[RUFF]

How many LPG Systems do you hear of developing a leak for no apperent reason? Then how many AC systems do you hear of leaking and needing a regas? This is the question you need to ask yourself when thinking of using LPG in an Automotive AC system. I know my answer from experiance. And no matter how much better LPG works in an AC system you could not convince me to use it. And i have also installed hundreds of custom Auto AC units.

[Mousie]

automotive refrigernt is 134A...
use it do not use r22 because it has difernt properties adn will blow up your compressor cos it dose not use the same oil

ALSO if the metering device is for 134a ( whitch 99% of automotice is)

other refrigernts just wont work

[HIGH ROLLER]

Iam a frigy also and there is no way that lp is legal in auto air, you are not even aloud to use a butane leak detector or any other flamable types when working on auto air so there is no way you can use it as the refrigerant, to many possible cause of ignition. All the other info on the wiring is right just putt all off your controlls in series with the clutch and your away.
make sure you get a licensed frigy to do it for ya
cheers Ben