Some 2006 Ford Explorers and Mercury Mountaineers, as well as 2007 Explorer Sport Tracs (all with 4.0-liter engines), may emit a thumping sound when the air conditioning compressor is turned on.
Ford said the noise is limited to vehicles built before Feb. 7, 2006, and is most likely due to the a/c suction line vibrating against the cowl in the engine compartment. Installing or repositioning a foam block, part #6L2Z-16738-B, between the suction line and cowl should insulate the line and eliminate the noise.
The illustration above shows the position of the suction line in relation to the cowl.
The circled area is the most likely point of contact between the line and cowl. If the foam block is already there but the thumping noise is still apparent, reposition it so that the adhesive side faces the cowl and it's in line with the suction line ferrel.
If the block isn't there, install it, following the same instructions outlined above.
Saab reported that some 9-3 models may exhibit an accumulation of water or damp carpeting at the footwell area on either side of the vehicle.
According to the Swedish carmaker, the water is probably coming from the lower a/c vents and is most likely due to the air conditioning system's inability to completely dehumidify the air in extremely humid conditions.
Installing a new air deflector, part #53 32 358, onto the lower portion of the blower housing should alleviate the condition quickly. To install the deflector, begin the job by removing the blower motor.
Now place the deflector on the blower housing so it sits on the front edge. Using the holes in the deflector as a guide, drill two .060-inch holes in the housing.
Limit the depth of the holes to .200-inch, or you could pierce the evaporator. Now attach the deflector to the blower housing using the screws provided.
To complete the fix, reinstall the blower motor, start the engine and check for proper blower motor operation.
Drivers of 2003-06 Pontiac Vibe models may complain of a whistling or hooting sound from the engine compartment under light throttle acceleration at speeds between 35-40 mph.
According to GM, the noise usually occurs with the drivetrain at normal operating temperature, and is most likely the result of resonance setting up in the transmission cooler lines. Installing new-design hoses, part #88974609, inlet side and part #88974610, outlet side, should muffle the noise and eliminate the annoyance.
Installation notes: The new hoses are unidirectional, with the yellow paint mark installed toward the radiator and the white mark toward the transaxle. A special retaining clamp, part #88974608, is required to hold the hoses together at the radiator support.
After the installation is complete, make sure the hoses aren't kinked.
Some 2005-06 Corolla and Matrix models with the 1ZZ-FE four cylinder engine may turn on the check engine light and store trouble code P0171 and/or P2195 in computer memory.
Toyota attributed the condition to an improperly functioning air/fuel ratio sensor. A new-design sensor, part #89467-12010, is now available to rectify the problem.
Drivers of 1998 and later Beetles and 1999 and later Golfs and Jettas may complain of a humming noise emanating from underneath the vehicle while making a slow turn with the steering wheel close to full-lock.
The noise will eventually go away as the steering wheel is straightened.
According to Volkswagen, the problem is limited to vehicles equipped with W/02J transaxles and is most likely due to the spider gear in the differential making contact with the one-piece thrust washer.
Draining the transaxle and refilling with an improved gear oil, part #G 052 171, should eliminate the noise in short order.
“Factory Fixes” is written by Jim DePalma, a 30-year veteran of the auto repair business who has served stints as a service manager, parts manager and ASE-certified technician. His column provides vehicle manufacturers' authentic factory technical service bulletins (TSBs) that have been condensed for easier reading. Mr. DePalma advises that techs always check with a dealer or repair information system for the latest revisions before starting to work on a vehicle. He can be reached via e-mail at [email protected].