My 98' crown vic one day started to make a buzzing sound on the highway when cruising at around 65MPH. The whole dashboard vibrated sort of like the vehicle had a bee's nest hiding under the dash.

Problem was not present when driving at slower speeds unless it was a windy day. Intensity and frequency of the noise varied depending on blower motor speed with the problem being eliminated if the climate controls were set to "off". Also, the noise was not present when the climate controls were set on "max ac", even if the blower was at high speed.

Since both "max ac" and "off" close the door in the heater box that draws in outside air, my suspiscion was that something was loose in path that the outside air comes in through. Had recently replaced the blower motor, so I knew the inside of the heater box was free of debris in the area that draws outside cabin air.

Noticed a crack in the grate that covers outside air inlet to the heater box and tried stuffing a thick layer of some folded up papers to insulate the grate from the metal of the car. Problem now only occured when driving the vehicle at higher speeds than before and when it did occur was not as severe as before.

Below are some pictures of the part I replaced to fix the problem. Well worth the $40 that it cost from ford.

(Click on any of the pictures above to view a larger version)

Later, I found that ford had issued a Technical Service Bulletin (TSB) on this issue. The text of bulletin is avaliable by clicking here.

Additionally, some crown victoria owners have expierenced vibration problems with the cowl cover on the drivers side of the car. Unlike the cowl cover on the passenger's side of the car, the noise is typically not affected by adjusting the blower motor speed and will usually be confined to the drivers side of the car at first. Some crown vic owners jokingly state that this problem is a speeding ticket deterrent system, since it warns you when your speed creeps over 75MPH. The problem is that the speed that the buzzing starts at gets progressively slower as time goes on. For instance very few people will complain about buzzing that only occurs at over 90MPH, but most all will complain about buzzing that starts at 60MPH.

If you hear noises in your crownvic that are present only when the blower motor is running, but are present even when the car is idling with the gear selector in "park", suspect that something has slipped past the intake grate and is wedged in the open area with the a/c condensor and the blower motor. Around here, pine needles are good at slipping past the screen. But depending on where you live in the country, you may well find other debris in there too. Cleaning the area in question is not difficult, just remove the four 8mm bolts that hold the blower motor in place, then unplug the blower motor and slide it out of it's case. When you've finished getting all the debris out of the area, slide the blower motor back into place and reinstall the fasteners. If you decide to test the blower motor while it's out of the vehicle, use two hands to hold it's case while you have someone start the car and adjust the blower speed. The motor moves large amounts of air and develops enough torque that it can easily spin out of your hands.

Questions or Comments?

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