"Dr.
Gizmo"
By Phil
Arendt
Select High Speed
Blower, A/C Quits
Question
1
During
the 100 degree weather I discovered the air conditioning does not work when I
place the blower control on high speed.
The fan does not work and I don’t hear or feel the air conditioner
clicking on and off by the engine. If I
place the blower switch on any other speed the air conditioner kicks in and the
fan work fine.
My
car is a 2002 Volkswagen Jetta with a 1.9-liter diesel engine. I checked all the fuses and they look
fine. What’s up? D.F., email
Answer
1
The
air conditioner, fan controls and engine are all connected to the engine control
module and heating, air conditioning and ventilation module. When one part fails, all kinds of weird
things can happen.
Since
it is likely you don’t have the proper diagnostic equipment to test the system,
in depth tests cannot be performed but there is a glimmer of
hope.
Since
the high speed position on the fan control is not functioning the first place to
look for a fault is at the blower fan resistor.
Whether this part plays a part in turning on the a/c compressor defies
logic to some extent, it certainly controls the fan speed. Check for an open circuit in the
resistor. If it failed, replace it. Once this part is replaced it’s possible the
compressor will not return to normal function, but it may. If it does you fixed the all of the
problems. If not, at least the blower
should function on high speed. Then you
can take the vehicle to a repair shop to have the trouble with the compressor
probed, but then again it may return to normal function.
Mystery
Over Wet Carpet Resolved
Question
2
I
hope you can help. Recently, I noticed
that the driver’s carpet is wet. I don’t
know why. It hasn’t rained much but I
have taken the car through a car wash.
Also, I haven’t driven through any puddles.
I
had a friend run my garden hose over the car paying particular attention to the
driver’s area. He also poured water on
the firewall inside the engine compartment and along the vents in front of the
windshield. I did not find any leaks
under the dash.
Do
you have any suggestions? R.G., email
Answer
2
Once
the water level is above the dash raise turtles, goldfish or guppies. All kidding aside, water might be leaking
into the passenger compartment from the air conditioner. Sometimes a drain on the air conditioner
becomes blocked with debris such as leaves.
When this happens the condensation that forms in the system does not
drain onto the ground.
Ask
an experienced technician to investigate the trouble. More than likely he will need to clear the
drain for the evaporator core.
Test
Drive And Diagnostic Tests Will Pinpoint Cause Of Trouble
Question
3
Dr.
Gizmo my 1997 Ford Thunderbird is my second car but it’s in great condition.
I use it around town for short trips,
errands and to drive to the train station where I catch the train to
work.
About
a month ago the 4.6-liter engine stalled.
It restarted but ran rough but I was able to drive it to a repair
shop. By the time I made it to a repair
shop the engine was running fine. I left
it for diagnosis.
The
next day a service advisor called and said that the mechanic working on the car
had found a code for erratic ignition but could not find a cause. The engine was running fine so he suggested
that I drive the car until the trouble gets worse. I picked up the car.
Since
the first time the engine stalled it has occurred several more times. Each time it stalls if I wait a few minutes
it starts, runs rough but I can drive even though the check engine light is
on.
I
have returned to the repair shop. The
mechanic finds the same computer trouble code but he does not know what causes
it. What should I do next? R.K., email
Answer
3
The
intermittent nature of the condition makes this a challenge to repair. Be this as it may, such a problem should be
detected by test equipment.
Some
of the causes for such a condition include problems with the ignition coils,
failing ignition module, failing ignition pickup or perhaps a problem with the
crankshaft sensor. Of course trouble
such as a corroded plug in one of the circuits associated with these devices
could cause the trouble.
If
possible leave the vehicle with your favorite shop and give them authorization
to drive the vehicle. A technician can
perform tests when it stalls which will help pinpoint the cause of the
problem.
Can’t
Predict Future Health Of A/C System
Question
4
The
air conditioner in my 1995 Honda Accord quit working. A shop checked over the system to find oil
was on the coil in the dash. They said
it is leaking Freon. I did not have them
repair the trouble because it’s expensive.
I’ve
owned the car since it was new. It’s in
great shape and has 87,000 miles. I have
taken good care of it with oil changes every 3,000 miles. I also follow the maintenance recommendations
in my owner’s manual. Until now the car
has never given me a bit of trouble. I
don’t want to get rid of it. Does oil on
the coil in the dash really mean it is leaking?
If it is, can it be repaired?
Since the car is old will other parts in the air conditioner fail? S.G.O., email
Answer
4
The
all-around good guy Dr. Gizmo cannot predict what will happen in the future, but
his crystal ball predicts that as a car ages chances are greater for parts to
fail. The part in the dash that is
covered in oil is the evaporator core.
Oil is a clue that refrigerant and oil has leaked causing the system not
to cool.
Because
of its design and construction the core of the evaporator can’t be patched in
order to stop the leak because if one leak is repaired it isn’t long before
another leak develops somewhere else in the core. And as you have probably learned many hours
of labor is involved just to get to the little bugger in the dash. A proper repair is to replace
it.
When
the part is replaced your technician will likely suggest flushing the entire
system which is a good idea. This
removes contamination such as small bits of metal from the failed evaporator
core. Also, he will install a new drier
which is a part that removes moisture that might be trapped in the system, it
stores refrigerant and has other functions.
In addition, he will pump all of the air out of the system until it holds
a certain level of vacuum. He checks to
make sure the system holds a vacuum indicating there are no leaks. Creating a vacuum also removes all moisture
which causes all kinds of problems in air conditioning systems. Once the system passes leak tests he will
pump in refrigerant and oil and run performance tests to make sure everything is
working as designed.
Once
repairs are complete there may not be any other troubles in the air conditioning
system for many years but no one can tell you nothing will fail on your way home
from the shop, two days later or six years from now. All a shop can promise is that the parts they
installed are covered by a warranty and everything is working as designed at the
completion of repairs.
Rattling
Noise Raises Concern Over Engine
Question
5
Recently,
I purchased a 2005 Mitsubishi Eclipse Spyder GTS with a 3.0-liter engine. It also has an automatic transmission and
87,000 miles. The car is in excellent
condition.
The
trouble is after the car has been parked for a few hours when I start it I hear
a rattling sound from the engine that lasts up to 20 seconds or so. After 20 seconds the rattle is gone. The engine runs fine but I’m concerned over
the rattle.
Since
the first time I noticed the noise on more than one occasion I had my Dad and a
friend start the engine while I observed the engine. I think the noise is coming from the front of
the engine. The belt is tight and looks
in good condition.
Do
you think replacing the belt will stop the sound? L.C., email
Answer
5
It’s
possible the belt is the cause of the sound but if it is not glazed, frayed,
cracked and in proper tension it is not the cause of the sound. What you may hear is a rattling sound from
the engine timing belt. With 87,000
miles it might be worn or the automatic tensioner is not responding to oil
pressure.
The
automatic tensioner is a hydraulic device that places pressure on the belt to
keep it tight. Hydraulic pressure is
supplied by the engine’s oil pump. It’s
possible the tensioner is worn and not applying pressure, sticking or not
responding to pressure due to restricted oil ports at the front of the
engine.
It’s
time to take the car to a repair shop for diagnosis. Maybe the timing belt and automatic belt
tensioner need replacement.
Vehicle
Suffers From Sagging Rear-End
Question
6
The
rear of my 2003 GMC Envoy sags at the right rear after the vehicle has been
parked for many hours or overnight. Once
I start the engine it returns to normal height and stays there as long as the
engine is running. Is there a spring or
hydraulic pump back there that is electrically activated that raises and lowers
the rear of the vehicle? Does it need
replacement? N.L., email
Answer
6
Your
vehicle is suffering from saggy rear-end.
The vehicle is equipped with air springs instead of conventional metal
coil springs. The air springs look
similar to a shock absorber but much larger.
When you start the engine an air compressor turns on to supply high
pressure air to the air springs in the rear.
This feature adjusts vehicle height depending on vehicle load. What seems to be occurring is a leak has
developed at the right rear air spring.
It’s also possible the line that supplies air to the spring has a
leak. To find out for sure a technician
needs to examine the parts.
To
fix the trouble he or she may need to replace the air supply line or air
spring. Also, there are aftermarket
conversion kits that replace the air springs with conventional metal coil
springs but once a conversion kit is installed vehicle height will no longer
adjust to vehicle load.
Thanks
for all of your great questions. Dr.
Gizmo can’t wait to answer more.
Phil
Arendt is a columnist, consultant and A.S.E.-Certified Master Technician. Readers may send questions to Dr. Gizmo at
P.O. Box 548, Cary, IL. 60013 or e-mail address drgizmo@drgizmo.ws. 08/06/2012 ® DR. GIZMO ©
1989-2012
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