Re: 5000 Turbo A/C questions

["Graydon D. Stuckey" <graydon@apollo.gmi.edu>]

On Sun, 15 Jun 1997, Ti Kan wrote:

> They were complaining that the A/C doesn't cool.  Upon playing
> with the system I discovered that the A/C will cool quite well
> if I set the climate control's temperature to 60 deg F (max cool
> setting), and the air comes out of the dash vents at high speed like
> it should in this setting.  However, if I set the temp to even one
> step higher, the system changes to only blow air out of the footwell
> and dashtop (defrost) vents, and the blower fan decreases to a very
> low speed.  This is with an ambient temperature around 90 deg F and...

My guess is that when you go to full cold, the system defaults to a max 
cold setting that is basically a manual full cold setting (this is 
similar to the GM products.)   As soon as you go one step off max cold, 
it goes back to automatic control, and then my guess is that your in car 
temp sensor is not working.    If the temp sensor is telling the HVAC 
computer that the car is at an appropriate temp already, then it will 
lower the fan speed and raise the temp door a little.

> sensor is kaput, making the control head "think" that the interior
> temp is cold?  So I looked through the Bentley manual and found that
> there are two temp sensors wired in series: the inside air temp sensor
> and the evaporator temp sensor.  Since the latter is under the plenum
> and relatively easy to get to, I checked it according to the Bentley
> and found it to be pretty close to spec (37.7 ohm, ambient around 80

OK, to clarify things a little, there are two _outside_ temp sensors, one 
in front of the radiator, and one under the cheap plastic cover at the 
plenum.   I'm not sure what algorhythm the computer uses to decide which 
of these to use, but these are both outside temp sensors.   The inside 
temp sensor is in the dash board top cover..    It has an electric fan 
which draws air over the sensor.   This is callled an aspirator.   You 
can check its operation with a cigarette or a match oor a candle.   
Generate some smoke near the inlet of the aspirator, adn you should see 
it drawn into the sensor.   With the key on, an the engine off, you might 
even hear the sensor although this is one of the quieter sensors on the 
market.   Hopefully that's not the problem, because its not easy to get to.

Later,
Graydon D. Stuckey 

"Cool name man!" - Jay Graydon   :-)