Re: 95 850 turbo A/C - a different kind of problem
"Thomas M. Keller" wrote:
> I have a 1995 850 turbo wagon, and I have read the discussions on
> various problems with the air conditioning system, but I think my
> problem is different.
> This just started about a month ago, when driving in high altitude,
> the a/c just gave up and started blowing (essentially) outside air. I
> should mention at the time that we were occasionally opening the
> windows to smoke, and it just seemed like the system got overwhelmed
> by the humidity.
> The next day, it happened again, under similar circumstances (it was
> also 90+ degrees F outside). But later that night, it worked fine as
> we drove across the state 350 miles home.
> Since then, it has worked fine, until a trip on a hot, humid day
> again. Then, we shut it off for half an hour, and turned it on again
> and it worked fine (we have an automatic climate control, and we just
> set the fan speed on "high" rather than "auto" which seemed to help).
> Then, when it got too cold, I turned the fan from "high" to "auto" and
> the A/C gave up again immediately, though the fan continued to run. I
> did just recently replace the blower motor on the fan, and it is
> working fine.
> It strikes me that - even though we are getting no codes from the
> system - there might be a problem with a switch or relay relating to
> the automatic setting, as the A/C seems to work perfectly every time I
> set it on high, but not on auto. Am I on the wrong track here, or is
> this something?
> South Dakota Tom
There's a couple of things that commonly cause these symptoms on 850s.
As the compressor clutch wears, the gap gets so large that when the
compressor clicks off, there is not enough magnetic force to pull the
clutch back on when the coil is energized. This can be cured by
adjusting the air gap (simple on a bench, not so easy in the limited
space on the car) or by wiring a relay into the circuit so the clutch
will get a higher voltage. (The S/V70 is wired this way.)
There is a switch on the back of the compressor that shuts it off if it
gets too hot. This switch seems to be set to too low temperature, and
has been eliminated on new compressors as well as the later cars. It's
mounted on the back of the compressor, simply disconnect the connectors
leading to it, and plug the 2 disconnected wires that are not part of
the switch into each other.
Thornhill (near Toronto), Ont.
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)