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The mkiv Supra Owners Club

Air con diagnostics


muckyman

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It can throw this error if it's in dim light, ie its in the garage and not outside. So it might not be an error at all.

 

Can you describe the aircon kicking in, do the revs rise, the aircon clicks into operation (you can see the compressor engage) and then it clicks off, and this repeats, just with no cold air? Is the Internal fan up medium/high Ie noisy?

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Ahh, right - it was in the garage so likely not a fault.

Yes, the revs rise and drop in time with switching it on and off.

There's no unusual noises from the internal fan regardless of the speed setting - it's just not cold. It's 'cool' at best but nowhere near as cold as on 90s Jap cars I've owned before...

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If you have a thermometer, preferably a probe, shove it into the air vent and set the flaps to the vents. A good ac result would be 7C on a normal day. Higher on a hotter day. If you are getting the compressor starting OK then you have sufficient pressure in the system to overcome the cut off. Next check needs snap on connectors, hoses and gauges. On the inlet side at static (compressor not running) the pressure should be around 70psi. Again this is ambient variable but if its under 50psi then you are low on gas. Fire up the compressor, It should now be running around 14psi on the suction, LP inlet side. With the compressor running assuming the LP suction side pressure isn't low then the high pressure should be running around 200psi. Any lower and either the compressor is tired or the charge is low. The pressures will vary dependent on the ambient temperature but the figures quoted here will be in the right park for a correctly charged system.

 

A Supra system holds 600g R134a so if its just a top off required then a small can would do it and you can buy these off eBay sellers. Best buy with uv dye in case you have a small leak that needs tracking down. You can buy all the snap ons and hoses plus gauges to from eBay sellers.

Edited by rider (see edit history)
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A Supra system holds 600g R134a so if its just a top off required then a small can would do it and you can buy these off eBay sellers. Best buy with uv dye in case you have a small leak that needs tracking down. You can buy all the snap ons and hoses plus gauges to from eBay sellers.

 

I should probably add that if you do top off a system yourself you do need to ensure you don't grossly overcharge the amount of gas. So only do it with a hose and inline gauge, Charge into the low pressure line, suction side of the compressor. The correct way to charge a system is actually on weight not pressure as pressure does vary with ambient conditions. Charging to inlet pressure with the compressor running (12 - 14psi) is fine but not the handbook way which is charging by weight but charging to pressure reading is a whole lot better than putting a full service can of R134a into the system because you have paid for it.

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