That Musty Smell May Be Mildew on Evaporator Core
Question: My 1998 Lincoln Navigator has developed a musty odor whenever I turn on the air-conditioning. I also seem to be allergic to this, because I start sneezing and my eyes start to water whenever this happens. Do you have any advice? I returned it to the dealership, and they say the vehicle checked out OK. This is not what I expected from my investment.--P.E.
Answer: The problem you describe is a classic case of mildew growing on a part of your air-conditioning system known as the evaporator core, which looks like a small radiator and is located under the dashboard. Its coils cool warm air blown over them by the fan.
The problem is that moisture from warm summer air condenses on the cool coils, creating the perfect biological environment for the growth of mildew-causing fungi. The microorganisms prosper in moist, dark places, thriving on nutrients from the air. The blower motor then spreads the mildew throughout the car, and you breathe it into your respiratory system, triggering an allergic reaction.
Ford Motor Co., Lincoln’s parent, has issued a series of technical service bulletins throughout the 1990s to solve this problem, according to the On-Demand computerized repair information system published by Mitchell International.
Ford offers a deodorizer that mechanics can use to kill the mildew without taking apart the dashboard or the air-conditioning system. The mechanic applies the material to the evaporator core by spraying it through the air-vent intakes and running the blower motor at high speed. The deodorizer is tricky to use and generally not sold to consumers.
The mechanics at your dealership may have used the deodorizer, but in case they did not, or they used it improperly, you should specifically request the treatment.
A somewhat less effective, though commonly used, do-it-yourself treatment for older cars involves spraying Lysol all-purpose cleaner into the ventilation intakes (located on most vehicles where the windshield meets the top of the hood) and running the air conditioner to operate the blower motor. The Lysol should at least help temporarily, though I cannot vouch for the resulting smell of the cleaner.
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Q: My 1994 Chrysler Sundance seems to shudder sometimes. I’ve had my mechanic at the gas station take a look at it. He tuned the engine, which didn’t seem to help. I’m reluctant to take it to the dealership. The car gets me where I’m going. --B.T.
A: Shudders are caused by a wide variety of problems. One item to consider is the transmission. Some Chryslers have been known to shudder when the electronically controlled automatic transmission goes through “lockup” at high speeds.
Lockup is a method that automatics use to boost fuel efficiency by improving the linkage between the engine and the drive train beyond what the torque converter can provide. The shudder is caused by a leaking bushing on the front transmission pump, which can be replaced. If you notice a whine coming from the transmission when the shudder occurs, you have found the problem.
This is one instance in which a dealership mechanic might have a big advantage over a gas station mechanic in diagnosing a specific problem, since the issue is well known on Chrysler transmissions. This problem is not cheap to fix. It will require more than half a day of labor, in addition to the cost of the replacement pump.
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Jeanne Wright cannot answer mail personally but responds in this column to automotive questions of general interest. Write to Your Wheels, Business Section, Los Angeles Times, Times Mirror Square, Los Angeles, CA 90053. Via e-mail: highway1@latimes.com.
