Hi, we've been told the gas in the air-con unit in our 1990 TP Magna is no longer sold, and will need a conversion and re-gas for $300.

I was wondering what type of gas was used and what is used now, and if this work and quote sounds about right.

Cheers!

The older refrigerant was called R12. The newer type is R134a.

That price of $300 is about par for the conversion if done properly. I'm sure it is quite profitable for the air conditioning shops but you are unlikely to get it done much cheaper.

However there is an alternative. A company named Hychill makes a refrigerant called HR12 that is compatible with both R12 and R134a. (i.e. if your air-cond. gas is low, whether it is R12 or R134a, it can be topped up with the Hychill product and there is no need for a conversion).

The product is very similar to propane gas and many d.i.y.'ers actually use propane. There is much debate about whether this is dangerous of harmful but the facts are often distorted by the self-interests of the protagonists. The average quantity used is about 300ml, which is fairly insignificant in a crash compared to the 65 litres of petrol or lpg in the fuel tank.

Anyway, there are some air-cond shops that do re-gassing with Hychill. If you ring the Hychill rep., he may be able to steer you in the right direction for your area.

Alternatively you can do it yourself by buying a can of HR12 (sometimes called "minus 30") from Burson Auto Parts or another Hychill stockist. That is what I did. You also need a gauge (or set of gauges) and hoses (available on eBay) and an adapter that screws onto the disposable can (from Burson).

The first time all-up cost is not much less than having the conversion done - Say $150 minimum depending what you have to pay for the gauge and hoses. However next time it will cost nothing or at worst another can of gas (about $40). Mine needed less than half a can and the air-cond is considerably cooler than before because HR12 is more efficient than R134a.

Thanks so much for all that information. How often is it usual to have the refrigerant topped up or changed?

That depends on the state of your air conditioning system. If the seals and everything else are in top shape, it should last at least several years between recharges. The average is probably more like every one or two years.

new dryer the new gas
and have a new TX valve fitted

I paid $300 for the conversion and re-gas in 2003

Dunno about you guys but in the TR air con was never touched and in 14 years still icey cold. $300 as said is about right...gotta change seals and stuff bit of a job to do. I'd personally just convert to r134a makes it much more service friendly

the old gas was R12: dichlorodifluoromethane.... an ODS 1 cu.m destroys 1000 cu.m of ozone
the system could lose about 60% gas and still get cold

the new gas is R134a: tetrafluoroethane.... a Greenhouse gas
lose 30% and the a/c struggles

hydrocarbon blends are all very well and good but keep in mind that they only use 1/3 of the gas required by r134a/r12 systems.... the gas acts as a coolant for the compressor.
another issue with HC is that the gases separate out in the system and leak out at different rates...
if HC was highly flammable then we wouldnt use it on aerosols

it is recommended that car a/c systems be used minimum 5 minutes a week to keep the o'rings, tx, etc lubricated
and even so a system will normally lose on average 3-5% of its gas charge every year.

HR 12 works brilliantly on a TP system, had mine topped up with it years ago, much colder and the compressor struggled less when it cut in.
My 2 TSs still run the original charge, R134a but when they need a topup I will use HR12 - local mechanic charges 120 for a top up.

couple notes -
Theres about 20 different HC gases available for air con systems - all have pros and cons. Do a google. R134a runs at higher pressure than R12 so early systems needed new seals, hoses etc. HR12 runs at lower pressure, so a strip of an R12 system is not needed.

Its the oil that cools the compressor, not the gas. Being a compressor it turns the gas into a liquid, creating a heat buildup. The oil carries this heat away.

The first refrigerant ever used was ammonia, used to make ice blocks for use in domestic chillers. Ask your grannie about buying blocks of ice to put in the chiller.

HC gases are highly inflammable, Just point an aerosol can at a candle to find out . . . . lol

Its the oil that cools the compressor, not the gas. Being a compressor it turns the gas into a liquid, creating a heat buildup. The oil carries this heat away.

HC gases are highly inflammable, Just point an aerosol can at a candle to find out . . . . lol

the gas does cool the compressor.... the cold gas vapor pulls heat from the compressor.... hence why running an a/c system with a low charge has been known to kill compressors

flammable gases are less likely to cause a problem than say petrol because they dissipate in the air (unless your car is in/above a pit)

i hope your mechanic is only "topping up" with hydrocarbon gases otherwise they are breaking the law

a good repairer will pre-test with nitrogen to determine any major leaks and system condition and rectify any leaks/faults before they regas the system

regassing without repairing a known leak/fault is illegal when using R134a

That is oh so wrong on many levels, ash, but I can't be bothered arguing, so lets say you are right, ok?

fine.. me right.. i can live with that
www.arctick.org good read for anyone who holds an a/c license or wants a reputable technician to fix their a/c