RE: ?88 5000s Climate Control - How cold is COLD?

["Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>]

> Thanks to everyone for their replies to the first question about a/c
> blowing
> lukewarm air.  It brings to mind, however, the question, "Just how cold
> should COLD be?"
> 
> As a test, I backed out of my relatively cool garage and put the a/c on LO
> (Auto).  The outside temp was 70+.  For the first few minutes, at least,
> the
> air was a pleasant spring breeze.  After a while, however, it just blew at
> "room temperature."
> 
> For comparison, our '94 Jetta GLS becomes quite cold after running the a/c
> on full blast for a while.
> 
> Am I just spoiled by a newer-technology a/c system?
> 
I think that you have got a problem in your system.  Others have mentioned
testing the refrigerant circuits ... that is definitely a worthwhile effort.
The other thing to keep in mind is that the 5ks from that vintage are
notorious for problems with the recirculate doors and blend door controls.
Unless you have the tempreature set to "LO" then the system will
deliberately run coolant through the heater core.  If the blend doors are
not set to bypass the heater core, you will not get the same performance
from your A/C as you expect.  The other thing that is supposed to happen
when the control is set to "LO" is that the recirculate door is supposed to
open, to allow the cooling effect to be multiplied as it is cooling air from
inside the cabin rather than air that is flowing in from the outside.  The
recirculate door can often get stuck in the recirc mode ... breaking the
plastic mount for the vacuum servo in the process.  This latter problem is
more likely to cause fogging of the inside of the windshield in cold weather
than your symptom IME ...

Based on your report that the A/C seems to work when cold, I'd recommend
that you look into some of these other things as well.  Another
recommendation is that you get a hold of the Bentley manual.  The cars
Climate Control system does have pretty extensive diagnostic capabilities,
and there are over 100 pages of diagnostic procedures in the Bentley ...

Another thing that I am planning to do as I rip apart my 5kCSQW is to
install a "standard" heater control valve in series with the vacuum unit.
This will allow me to manually decrease the flow rate to the heater core
during the summer time, when it really isn't needed.  

Good luck with your problem!
Steve Buchholz
San Jose, CA (USA)