Falcon ventilation systems run on vacuum, over time the vacuum lines can develop leaks, the problem you mention is very common. Pull the control panel out and see if theres any obvious leaks, other than that you'll need to get it looked at by I dont know who.....
As for your ac, just get a new reciever/dryer and fill it with R134.
You might be advised to spend a few hundred on a "conversion" but its a waste of money. The dealer i used to work at charged big money for an alleged conversion but only filled the old system with the new gas anyway!
well it will be defintely R12, anything before around 93 /94 was R12. R12 is not illegal to use, it just cant be either manufactured or imported into Australia. Some firms still have some R12 available ( we do, but being in Tassy wont help you) so unless you can find someone with it, you will have to convert. Conversion costs should only be aroaund $160, so dont get ripped off, ok?
2002 Narooma Blue Manual TS50
Is the gas completely gone though? if so you might want to find out why otherwise you could end up with a huge repair bill.
Check for light oil spray on the A/C compressor in particular as this is an $800 job if stuffed.
Some places may have a bit of R12 lying around but its getting rare now. There are direct replacement gases that don't require the conversion too but again, there may be a good reason for no or low gas and you might find you need more than a gas up, the conversion usually consists of new o rings at all joints, new oil and a new receiver dryer all of which are probably worth doing in this situation.
As other have said, the HVAC controls are vacuum operated and it defaults to demist when no vacuum exists, first thing to check would be the supply pipe off the manifold in the engine bay, from memory its a hard green pipe nd runs of a 'christmas tree' on the intake, also check the heater tap vacuum feed pipe is connected (its under the intake manifold) as this causes the same problem.
the poisition controls are vacuum operated in the ea falcon, the most common cause is the main vacuum hose coming of at the vacuum tree on the manifold as kieron said. this is the black hose and the heater tap is the green one, the other problem is behind the control panel, there is a white three way connector with a green vacuum hose going to it they often pinch off. r12 is leagal to use but those of us who care for the environment and have a consience will avoid it. most of the r12 is reclaimed gas, some companys clean this gas properly but the majority of people just put it staight into the next vehicle. this causes lots of contamination problems as far as oils and gases go.there are so many oils on the market now it is not funney, manufacturers for the austrailian car market only us pag oils which are more expensive but are more reliable in the long term. blend gases have also flooded the market, i would recomend people dont use these as they have a problem called a gliding effect where the differant gases can leak from the system at differant rates, affecting a/c performance dramaticaly with very minimal gas loss.
very rarely is it just a conversion from r12 to r134a, this is because most vehicles have gas leaks and converting it wont fix the problem.
a/c systems are very expensive to fix and even more expensive if they are not fixed properly the first time, and often result in compressor failure.
hear is a list of common gas leak problems for a ea falcon.
pressure relief plug on receiver drier
condensor (less common) unless you own a ef el falcon.
engine thermostats (because viscous fans dont work unless engine is up to temp and therefor dont draw air across condensor eficiently)
flap in fresh/recic dump box(lever breaks off)
there are probably some things i have forgoten but basically i'm saying get the job done properly by a reputable technition and pay the $ otherwise save your money.
also we have two compressors to suit ed v8 falcon new, i think they will also fit ef el v8 if anyone is interested.
i just checked out the threds at the bottom of this page and it just confirms the confusion in our industry.
r134a is equaly as efective as r12.
dont use lpg in car a/c systems thi is extremly dangerous. the south austrailian government permits this but when was offered to gas there intire fleet for free they refused. it only takes a leaking evaporator overnite and it might be the last time you turn on the iginition key. lpg does work but not as efficiently as r12 or r134a.
i believe there are four things you dont skimp on,
Shed guy, I recall back in the beginnings of R134 (EB SII was one of the first to adopt it) that R134 was not as efficient and A/C systems had to be uprated to give equivelent performance?
R134 does run at higher pressures and has smaller molecules, both of which will cause problems with R12 systems, namely increased demand on the compressor and any joins/seals, from memory many R12 systems used rubber o rings (black) and R134 needs neoprene(red and green I think?) + R134 will sludge the R12 oil causing no lube to get to the seals/compressor.
Sure you can get away without the conversion, but you will greatly shorten the life of the A/C system which is probably well worn as it is.
R134a does run at a slightly higher pressure than R12 because of it's molecular stucture, the main limiting factors are condensors (or air flow) and tx valves. Theoreticaly you should replace the tx valve as part of the retro fit but the cost starts to climb significantly and most cars will cope with the origanal tx valve, but in saying that falcon tx valves are easy to change from xa to el models as they are internaly equalised and are located in the engine bay, (unlike most european and japanese cars which are behind the dash).
the problem with R12 o'rings is that R134a oils (ester and pag) effects them, The new o'rings are made of a rubber called H N B R.
converting a system to R134a has a greater effect on compressor shaft seals especially carbon type seals and ester oils are the main offender here, the reason for this is because most a/c systems will develop leaks in time and when this is not corrected quickly the compresspor runs hot and burns the oil leaving a dirty film on the inside of the pipes etc. This is where ester and pag oils come into it, ester oils basicaly dislodge this junk and wear out compressor seals quickly and pag oils dont do this, (most companys use ester oils because of cost).
mineral oils (R12) will usualy lay dormant in low pressure areas (evaporators) and dont mix with ester and pag oils,this is another problem because who knows how much oil someone has previously added to the system.
flushing oil and contminants from a system is again another problem because you can again contaminate a system by what you use. For example using lpg (which is a common practise) leaves a residue and in term changes the structure of the gas. The proper way is to use R132b refridgerant,(i personaly use R134a on my own cars but the cost is high).
the au/ba falcons use a ccot system (compressor cycling orifice tube) again purely because it can handle a wider range of temperatures compared to a tx valve system,(basically they can sell a car in melbourne and in darwin and it will work well).
this also true in cold climates were they use a/c purely for demisting while having the heaters on max.
R12 A/C systems can be gassed with R134a by adding a oil by ROC oil which you add on top of the existing oil in the system, I don't remember the exact name but I can find it , you don't have to change any o'rings or seals when using this oil. You then regas the system with 80% of what is recommended if filled with R12 to allow for the higer pressure. I would recommend a dye added with the gas for leak detection if you have one. You should also change the receiver/drier to suit R134a gas.
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