SJ6 Series 3 Aircon Switch

Whenever I turn on the aircon the fuse in drivers side under steering ng wheel blows. It is the one that has the 15A aircon relay and clutch fuse. Can anyone suggest what this issue might be linked to and where I should start looking. Thanks.

Hello AJ (your name?)
You may have a short somewhere.
You should determine if it’s the primary (relay and climate control circuit) or, most probably as it’s a 15A fuse, the secondary (AC clutch and Supplementery air valve).
Measure the resistance of the clutch, it might give you a clue.
Discconnect the clutch, if the fuse blows it’s the primary, if not it’s the secondary.

Thanks, can you give me instructions on how to disconnect clutch or direct me to a link .TIA.

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Turned ‘on’ all AC electrics are fed through the fuse, sir - no easy solution, it may be a component or a shorted wire…‘somewhere’.

First; get plenty of spare fuses - it’s a trial and error process…:slight_smile:

Disconnect clutch wire at the clutch; if the fuse then holds it is the clutch itself - if fuse still blows, its not that. This is the only item that draws fairly high power - other items are low powered, relays and microswitches, and blown fuse implies a short.

Check the fuse holder; the ‘out’ wire of the fuse may be shorted to ground - the fuse holder is a weak point.

The next step is to possibly isolate the fault area; disconnect, in turn, the AC amplifier, then in turn the two multiconnectors - observing the fuse at each step. You may also access and disconnect the water temp sensor clamped to one water hose to the heater core…

To inspect other all parts and wires is a long process - unless some clue appears…or a lucky strike. It’s not a common symptom…

Frank
xj6 85 Sov Europe (UK/NZ)
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Just disconnect the plugs of the blow out fuse, the small black rectangular thingie right by the compressor.

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That is the thermal fuse for the clutch, Aristides - and may not be fitted on his car. If it fails there is no power to the clutch, but won’t in itself blow the AC fuse. But anything may cause a short…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
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AJH68,
You did not mention the model year of your car, and it does matter. If your car is an earlier XJ6 like my former 1984 XJ6 Vanden Plas, and no one has modified the wiring, it will have the A/C wiring harness shown in the attached picture in the left front of the engine bay.

Circled in white is the connector for the clutch power on a Green-Brown wire. Circled in yellow is the white connector for the Superheat Switch on the rear of the compressor. Circled in red is the connector to the A/C compressor. Circled in green is the Thermal Fuse, and circled in Blue is the ground wire connector that is attached to a nearby bracket bolt.
If your car’s A/C system has been modified and/or is a later car (1986 or 1987?) then the wiring is different because it has a High Side Low Pressure Switch in the compressor instead of the Super Heat Switch.

Paul

Thanks everyone , will let you know how I go. It is 82 model built in Australia. First of the Fuel injected I believe. But it still has distrubutor.

AJH68,
Jaguar introduced fuel injection in the Series II XJ6s in the late 1970s and in the first of the UK produced Series III XJ6s in 1979. I am not sure what the schedule was for the Jaguars produced in other countries. Also some carburetor equipped Series III XJ6s were produced all along although I don’t think many made it here to the USA.

As far as distributors, all Series II and Series III XJ6s had them from the factory.

Paul

Paul