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Friday, August 17, 2012

Northwest Herald Dr. Gizmo Column Dated August 10, 2012

 "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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