a-c fan doesn't turn off, drains battery

on our '97 960 wagon, a fan or fans related to the a-c doesn't turn
off when you remove the ignition key and step away from the car. hours
later you return to the car and a fan or fans are still whirring in the
engine compartment. this does not seem to be the radiator fan. after a
day or two of this, of course, the car battery is too weak to turn-over
the engine. the a-c was recently recharged by a neighborhood mechanic,
raising suspicion that something got cross-wired or otherwise messed
with. any thoughts? many thanks. art

 

You might ask the mechanic to put it right.

 

took it to a different one today and he, for $138, was unable to
find any problem with his battery of diagnostic equipment. he will,
nevertheless and i am sure, cash the check.

 

I don't know about the '97 960 but on my '01 S80 the cabin fan comes on
about an hour after you shut off the engine and runs for a period of time to
dry the condensation off the evaporator. This is intended to stop smells
from mold etc. in the a/c system. I have never had the battery go flat from
this; it only does it once per engine cycle. If you shut down and there is
a fan running it most likely is the electric fan for the radiator cooling it
down. This should also shut off after a short time.

If your battery is going down maybe it is time to have it replaced?

 

just a guess, but when the first mechanic recharged your AC system, he
probably had to bypass the low-pressure switch in order to force the
compressor to run and pull in the refrigerant, until the pressure built up a
little... in the past, I've done this on cars using a simple jumper wire,
but perhaps he did something different, and forgot to un-do it when he was
finished...

 

perry: interesting. will contact him about that. it does, indeed, seem
that a switch is or was malfunctioning during a streak of very hot
weather here. would not that have shown-up during a later inspection
w/diagnostic equipment? thanks. art

 

I was thinking that he might have run a wire from the (+) terminal of the
battery directly to the compressor clutch, to force it to pump even if the
pressure in the system was too low... that would allow it to pull in the
refrigerant and become pressurized enough that the jumper wire wasn't
needed. However, he might have forgot to remove it, and since the compressor
clutch and the electric fan in front of the radiator are energized together,
that might be the problem you are having now.... the combination would
certainly drain a battery fast!....

 

perry: very interesting. will investigate. art