On Fri, 07 Aug 2009 21:44:57 +0100, David J wrote:

On switch-on, after about 30 seconds the motor/compressor can be heard
running, together with some 'flow' noises. However the rear radiator
produces no heat, and the interior is not chilled at all.

Heat pump not working... As the compressor runs one can only assume
it is out of gas for some reason. How long did you leave it running
to determine that the raditor wasn't getting warm?

A local refridgeration company should be able to re-gas it for you.
How ever if you don't find the leak it will need doing again, and
again, and again.

I have removed a cover from the freezer section, which exposes a
circulation fan, and a finned evaporator.

Frost free freezer, never very reliable. Most (all?) of the problems
reported in here about freezers are related to frost free designs. Is
that much of a chore to defrost the freezer every six months or so?

Have you contacted Hotpoint? What warranty does it have? Even if only
12 months you can still argue "unfit for purpose", 3 years is a short
life for a fridge/freezer even a frost free one. I'd say 5 years as
minimum, 10+ average, 20+ good.

There appears to be just one motor/compressor for the upper fridge and
the lower freezer. If so, how do they get 2 different temperatures?

They rely on the fridge being opened/heat gain and that calling for
coldth, the freezer part is cooled as part of the process hopefully
to low enough temperatures. This is why a fridge/freezer in a place
outside it's design temperature range, say a garage might let the
freezer get to warm because the fridge part doesn't gain enough heat
to trigger the heat pump.

--
Cheers
Dave.