>From: israel@merck.com
>Subject: XJ6 Questions
>
>First question concerns the Air Conditioning compressor.
>Turns out that the new compressor does not accommodate a thermal
>sensor and the old one cannot even be used. My question
>is, what purpose does this
>serve and can I get by without it? What about the lead from the
>thermal fuse to the sensor; does it conduct electricity or heat?
>Can I just leave it hanging or do I connect it to ground?
The sensor is a device that shorts to ground when there is a problem
in the compressor. The thermal fuse has three connections: the wire
coming from the control system (12V when A/C is operating), the wire
going to the compressor magnetic clutch, and the wire going to the
fault sensor.
During normal operation, the thermal fuse simply acts as a connection
to allow the 12V from the control wire to go directly to the magnetic
clutch. If a fault occurs in the compressor, however, the current
going through the sensor to ground heats up a resistor in the thermal
fuse and melts a connection, breaking power to the magnetic clutch.
All of this makes sense as a means of preventing major damage to the
compressor in the event of a minor problem, such as loss of freon.
Unfortunately, it no longer makes sense from an economic standpoint.
Due to CFC regulations, the freon costs as much or more than the
compressor! If there is a problem anywhere in there, it is generally
suggested the compressor be replaced whenever the freon system has to
be recharged anyway. Therefore, a fuse system protecting the
compressor is unnecessary.
No, the sensor will not reinstall in the new compressor, but you don't
need it anyway -- nor the thermal fuse. Simply connect the control
wire directly to the magnetic clutch, and you're good to go. Pitch
the sensor, the thermal fuse and the associated wiring.
>My second question regards a fuel smell which only occurs when I have
the
>windows down or the sun-roof open. The gas tanks show no signs of
leaking
>and I just recently replaced the carbon canister and fuel cap seals.
PLEASE don't ignore this! The car is not supposed to smell. If you
can, find a way to jumper power to the electric fuel pump so you can
run it with the engine off. This can be accomplished on an XJ-S by
jumping out one relay in the boot, but I don't know about an XJ6. Get
the fuel pump running while everything else is quiet, and trace the
entire fuel system, including underneath the car.
You problem is more than likely a tired piece of interconnecting hose,
possibly within an assembly involving metal tubing, brass fittings,
etc. Rather than replace the entire assembly, you can replace the
hose itself with fuel injection hose from an auto parts shop. Be sure
to get FI hose, normal fuel line cannot handle the pressure, and try
to get special clamps with it -- normal screw-type hose clamps
sometimes fail to get a good seal under these pressures. Make sure
the assembly is the same length when you're done. Lastly, if the hose
portion is within sight of the exhaust system, wrap it with aluminum
foil to protect it from radiant heat.
--
--- Kirbert
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| Kirby Palm, P.E. |
| palmk@freenet.tlh.fl.us |
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|