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The mkiv Supra Owners Club

Aircon Gas


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All cars from 92-93 and on has R134 from factory, it was a new standard by then

R12 is freon IIRC?

 

You can go with propane (same as for the camper stove) but I'd go the extra route with the tracer gas and a complete vaccum of the system so you don't mess anything up.

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The new stuff in the likes of Mercedes is £800 for 5kgs. The R134 is about £80 for 15 kgs. Such is the price of going green. Most people are putting R134 in newer cars as the price of a leak is causing customers to blow their fuses. Madness!!

 

The Merc stuff is so expensive because of two things, firstly the name and secondly it'll be a gas/PAG compressor oil mix. It is always good practice if you have had a catastrophic leak to add back top off oil with a new charge, the compressors range from ISO 68 to ISO 220 weight PAG oil but a general ISO 100 will pretty much do as a top up.

 

A healthy air con system will loose up to 10% of its charge each year as it'll be running between 17psi suction to 200psi discharge. So, you should have your system topped up every 4 or 5years anyway. Its when the system falls so low on gas it'll start pulling a vacuum on the low pressure side that you can start to get issues with moisture getting pulled into the system.

 

There are loads of sellers on eBay for R134a, port coupling and gauge sets. You only need the low pressure (blue) port coupler and low side pressure gauge to charge the system. Its a really simple job but must always be done with gloves and specs on as liquid refrigerant will cause burns. With the car running if the a/c pressure is too low the compressor wont engage. The pressure in the system standing should be around 70psi though this is obviously dependent on weather. As soon as the compressor kicks in the LP side pressure will drop and anything below 17psi needs a top up of gas. By opening the screw valve on the gauge set that is coupled to the LP service port and R134a cylinder you can start to feed gas into the system (always feed in gas - don't invert the bottle that could then feed in liquid. Some bottles do have two separate liquid and gas take off valves).

 

Once you have the correct gas content in the system the condenser sight glass will show a steady stream of liquid with no or limited amount of bubbles. Don't be tempted to overcharge a system, that can result in hydraulicing of the compressor which is usually terminal.

 

It really is an easy job to do yourself if no recovery of old refrigerant or drying of the system is required.

 

http://www.refrigerantgases.co.uk/shop/index.php?_a=product&product_id=39

 

http://www.ebay.co.uk/itm/REFRIGERATION-AIR-CONDITIONING-R134a-MANIFOLD-GAUGE-SET-/400320857218?pt=LH_DefaultDomain_3&hash=item5d34fb8482

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