Spanner-How to survive your local garage

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Sun 6 Oct 2002 15:03
Spanner-How to survive your local garage - Dave N
Read the article in todays Sunday Times motoring supplement. I know they're trying to compete with the Saturday Telegraphs motoring supplement, but this was a bit below the belt. The article seemed to be based on zero technical knowledge, so I felt compelled to write the following in complaint:-
Sir, whilst we all appreciate efforts to expose sharp practice, please ensure you base these efforts on a sound knowledge of the subject matter.

Air con doesn't work by 'mixing gases', but by the condensing and evaporation of a single gas, utilising the heat energy from the cabin to change the state of the refrigerant from a liquid to a vapour, thereby removing heat from it. There is no pumping out of the gas, or mixing of gas with warm air. The system is sealed, and gas isn't 'used'.

When servicing a system, no 'airlock' is generated, I believe you mean a vacuum is generated. If air is mixed with the refrigerant, as you imply, then the system will not perform properly as air is a non-condensable gas.

As for 'twiddle with your controls', I'm not entirely sure how you believe this is achieved. Cars with climate control monitor the interior temperature using variable resistance sensors, so the only way to 'twiddle' is to change the resistance of the sensors for a given temperature. Are you implying that those involved in sharp practice go to the trouble of adding resistors to the circuit, thereby fooling the climate ECU into thinking it is seeing lower temperatures than it really is? What about those vehicles that don't have climate control, maybe they are shown a vent temperature using a specially rigged thermometer? All manufacturers publish a specification for the performance of the system, and it is usually along the lines of:- engine speed at 1500rpm, temp setting LOW, fan speed max, this should then produce a temperature of between 4 & 6 degrees at the centre vent. I would imagine people know if the system is performing, not by the temperature the system says it is maintaining, but if it is comfortable or not.

It's a shame you seek to trivialise the thermodynamics involved in air conditioning, a bit like saying an internal combustion engine only needs a bit of fuel and a spark, to justify your claim to be championing the consumer. I trust you will now be issuing a correction, as you have had to do already regarding the running costs of the Volvo, and the 0-60 time of a 1969 Ford RS1600?


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Sun 6 Oct 2002 16:08
Spanner-How to survive your local garage - Godfrey H {P}
Drat, nearly bought The Sunday Times today. If there are any more like that it looks like I missed a good laugh.:-(
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Sun 6 Oct 2002 18:56
Spanner-How to survive your local garage - lezebre
Way to go DN !

You after Honest's column? :)
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Sun 6 Oct 2002 19:29
Spanner-How to survive your local garage - Pugugly {P}
"don?t think even trading standards or the motoring organisations have clocked onto this lark yet."


Probably 'cos its not a "lark"
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