Dream
Job
Have you ever been trying desperately to diagnose a problem vehicle, only
to go home and dream about it that night? You're probably thinking I should
seek professional therapy, but it did happen to me once - really! I spent
most of the day trying to figure out why the dual zone temperature control
system on a 1994 Oldsmobile® Ninety-Eight® wouldn't work properly.
That night, a dream gave me the answer.
The dream went something
like this.
I was on a game show
where the host read the answer and the contestants were supposed to supply
the questions. (Sound familiar?) Choosing the Heating/Air Conditioning
related category from the five automotive headings listed, I said "I'll
try HVAC Attack for $300!"
The answer, "These
three conditions can cause temperature control problems with the dual
zone HVAC system on a 1994 Oldsmobile Ninety-eight or Eighty-eight".
Remembering a General
Motors® technical service bulletin I had once read on my ALLDATA®
automotive information system, I quickly pushed the buzzer and replied,
"What is, the solar sensors may not be properly positioned, the
in-vehicle temperature sensor may not be properly installed and the driver's
side temperature valve linkage may be out of adjustment?" I awakened
before the game ended, but the answer stuck in my mind. I couldn't wait
to get back to work and test out my nocturnal revelation.
The next day, after
retrieving the TSB from my automotive information database, I followed
the inspection and adjustment sequence as outlined below.
Solar Sensor Orientation
(See Figure 1)
To
check if the solar sensors are in the proper orientation, look down through
the windshield and identify the locator tabs of the solar sensor.
The larger tabs of
the sensors should be pointed toward each other. The tabs should also
be up against the stop block.
If the sensors are
not properly positioned, remove the defroster grill. The solar sensors
can then be turned into their proper positions.
In-Vehicle Temperature
Sensor - (See Figure 2)
The
in-vehicle temperature sensor may not be properly sealing at the knee
bolster. If the sensor is not sealing properly, it will be sensing the
air temperature from behind the I/P, which will cause the HVAC system
to over heat or over cool the passenger compartment.
To check the operation
of the in-vehicle temperature sensor, verify that the aspirator grill
will hold a 45 mm x 45 mm (1.75" x 1.75") piece of 20 lb. bond paper (typical
copier paper) when the blower speed is set to three bars. If the aspirator
grill will not hold the piece of paper, verify that the foam seal is properly
installed and that both tabs of the in-vehicle temperature sensor are
properly secured to the knee bolster.
Driver Temperature
Valve Link - (See Figure 2)
When the temperature
valve link is out of adjustment, the owner concern may be that the driver's
side of the vehicle seems hot or cold, or that there is a great temperature
difference between the driver and passenger sides. To identify if the
link is off or out of adjustment, push back the rubber stoppers in the
glove compartment allowing the glove compartment to swing down. With the
glove compartment out of the way, you can see the linkage.
To adjust the temperature
valve link:
- Turn ignition "ON".
- Set temperature
control to 90° F (32° C).
- Wait for programmer
arm to finish traveling to full hot position.
- Pull HVAC case
rod to the right until a light resistance is felt.
- Pull plastic lower
link to the left until slack is removed and attach to HVAC case rod.
The whole process
took only about an hour. When I finished, the temperature control system
was flawless. Sitting in the passenger's seat, enjoying the cool breeze
from the dash vent, I thought one thing I learned from this experience
was I should always check technical service bulletins first. Hey, maybe
that was what my dream was really trying to tell me after all.
©
2000 ALLDATA LLC
