On 2/16/07 12:50 AM, in article
1171608605.975872.51040@k78g2000cwa.googlegroups.c om,
"techman41973@yahoo.com" <techman41973@yahoo.com> wrote:

> I have a 97 Accord with a bit over 200K.
> For the past 20K or so, I hear an intermittent hissing sound below the
> glove box when the AC switch is activated. Cooling seems to work fine,
> verified this summer in the scorching heat of the southwest. Other
> than being quite annoying, I am wondering if this is a clue that
> something is about to fail.
> Thanks
>

You're probably just hearing the vacuum activated dampers & flaps moving
into place. If it hisses periodically after you start it going, it could be
a vacuum leak or an intermittent contact in the switch.

Check that the radiator (not just the overflow tank) is full to eliminate
the possibility of air bubbles in the coolant moving through the heater
core. It could also mean the charge in your AC is not right, in which case
you're hearing the fluid/gas bubbling through.

Get somebody familiar with that model car to listen to it. Someone who
works on these things for a living will recognize your hiss instantly and be
able to tell you if its a problem or just the nature of your car.