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Fizzbang

Aircon Regassing?

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I have a rav 2008 and about to take it down through Spain, so, I need to know if it is worth regassing the Aircon..I bought it from a dealer in May and only use it at weekends, so I am not entirely sure on the rough lifepan of a gassing before it needs redoing...Any thoughts?

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If it blows cold in the warm weather don't bother.

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Agreed - if it produces really cold air within a minute of switching on, it's OK. Air con gas charge can last years before needing replacement (it finally leaks away), and the symptom of needing a recharge is simply lack of really cold output.

Chris

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Had car serviced at Mr T this week 80000/7 years. They said it had never been regassed and needed it . I got it done at local garage for £45+ vat which was cheaper than Mr T and it has made a difference -much cooler quicker.

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I'm sure I've seen somewhere (maybe on wheeler dealers?) that when the air con is working right, you should get a temperature of 5 degrees at the vent. My 4.2 is due for regassing now, but have been putting it off due to cost.

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Air-con should be used on a regular basis to ensure the innnards are propely lubricated so in effect under-use is worse than over-use.

There are companies that will service the system and if it ain't any cooler afterwards the don't charge.

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No win, no fee sort of thing.. that's certainly worth a google! Cheers James

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......but if they don't initially check for leaks and just refill and take yer cash as do The Really Kwik Tyre Fitters Ltd., why not just chuck your money down a drain.....?

Mr.T will cut a deal on air con, weigh that which they remove, top up with correct coolant and mainly do a leak test.

Big Kev

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Good advice from everyone.

Don't get it done on the cheap (around £40 should get a good job).

Don't let anyone just do a "top up" with an aerosol or small cylinder.

Gas should be removed with a portable/wheelable bit of workshop kit. A vacuum pump removes what's left of the old gas, and registers its weight. It can take 10-15 minutes to completely evacuate the old contents. The same piece of kit contains a cylinder of new refrigerant, and the machine is set to inject the manufacturer's required amount (usually around 400-500g). Also injected is a special lubricating Oil, also to the vehicle manufacturer's spec and quantity. The machine finally registers the amounts injected, and if left connected will display the pressure (and any immediate leaks). The bit of kit also recovers the old refrigerant for recycling or future use, and at £2000+ backstreet workshops tend not to have it! Refrigerant must not be discharged to the atmosphere.

Never top up on a DIY basis. Many top-up aerosols don't contain the lubricant, and you're left guessing at the weight of refrigerant injected and contained. Correct weight of contents is essential to proper performance.

For suspected leaky systems, a fluorescent dye can also be injected which will show up leaky joints or pipework.

For older vehicles, expect the refrigerant not to be of the type originally listed. Environmental and technical standards have moved on.

Chris

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The latest machines are theoretically idiot proof, you connect up the car and program in the exact model and the machine should do the rest. These machines are found in good garages and also Bodge Fitters.

The problem is when you give a complex machine to an idiot they don't look after them, and don't understand when they have gone wrong or what the readings mean.

When the machine works correctly it extracts and weighs the refrigerant and importantly tells you how much of the PAG Oil has been extracted.

From this you know if the system has a leak and how much Oil to put back in. This is important as most of the Oil stays in the system when you drain the refrigerant and its bad to have to much or too little Oil. An initial Oil fill (amount specific to the car) is put in the factory and it distributes in the system

Oil typically distributes itself through the system as follows

Compressor 50%

Condensor 10%

LP hose 10%

Evap 20%

Drier 10%

So typically a drain and recharge may only extract about 10 -20% of the Oil in the hose etc

Thus after the drain cycle if the machine says 0% Oil extracted you know you have a machine problem !!!

However without intervention the machine automatically will put in what it thinks it got out !!!

Thus 0% back in and you are running on low Oil .

These machine are highly complex and some of them can be damaged and need servicing if an owner has used one of the DIY top up cans that contains a sealant.

If you choose to get your AC serviced make sure the operator know how the machine works, if he says "its fully automatic mister I just press a button " think twice.

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Any equipment is only as good as the operator - that rule applies to anyone doing air-con servicing regardless of whether they are a dealer or not. Any time I have had an air-con system serviced I have always asked the operator one simple question. I say casually - how does air-con work? If they can't explain in simple terms - walk away.

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You lads certainly know your "Stuff" on A/C. Credit to you all.

Still Deaf Clare

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It works on the opposite principle of "when you compress a gas it raises the temperature". If you hold your finger on a bike tyre pump it gets hot. If you decompress a gas it gets cold (if you deflate a truck tyre the valve freezes up).

Fluid id forced through a needle valve at high pressure and emerges as a low pressure gas. It is then directed through a small radiator in the inlet to the heater so all incoming air is conditioned whether hot or cold (providing it is switched on). As the outside air hits the cold radiator it has the same effect as a freshly pulled pint of cold lager and moisture forms. As this trickles off it pours out of the drain tube as the clear water you see dripping out of the bottom of the car. In this way the incoming air is dehumidified and it is good for demisting windows AND keeping you awake better than moisture laden air. Some people grumble about dry throats but that is only temporary and they should give it chance.

For these reasons, A/C is better left on despite the additional cost which may be up to 10% around town, less when cruising. It is far better for the system and also compressor clutches which don't like idling/being switched off for long periods.

Mine is never switched off and it still averages 40 during the warmer months.

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and one more tip...

To prolong the life of the belt-driven AC clutch, it's a good idea NOT to switch on the AC at normal driving revs, but to momentarily dip the clutch and switch on at idle. This prevents a huge snatch on the multi-disc clutch, which is usually what destroys them. Replacement costs are huge, and may involve replacing the complete AC compressor on some vehicles.

It is safe to switch off the AC at any engine speed.

This is advice from a specialist AC workshop here, who have to sort out ruined AC clutches.

Chris

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The 4.3 (and the UC Clare) has a "smart" compressor. It can vary the output dependant on load by increasing or decreasing the angle of the piston plate. This way it will start up "light" and then increase the output after the engine has started and reduce the shock when switching on. It can aslo crank up the pressure on a really hot day and idle on cool days - dehumidifying on demand in accordance with humidity and temperature.

The lightweight plastic pulley is desined to break and freewheel if the compressor develops a fault.

All clever stuff!

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