Chrysler Repair: ac blower, plymouth grand voyager, amp fuse

Question
I have a 1999 plymouth grand voyager.  The ac works but the blower works sometimes.  I could hit a bump in the road and it my come on or could be driving and comes on or even when I turn my car on it works.  My mechanic changed the relay- but now it works less.  What do yo think it could be-I hate to keep changing parts and spending unnecessay money.  thanks

Answer
Hi Joann,
I'm a bit uncertain about a '99 because my most recent manual for the minivan is '98, but in that model the blower motor appears to be powered by a 40 amp, fuse #21 in the box near the battery, under the hood; and the relay that controls that fuse's current is a 10 amp, fuse #12 in the fuse box under the dash on the driver's side. Any fuse can develop a crack in its internal wire which can cause it to lose the current flow spontaneously, and then recover unpredictably. So inspecting those two fuses for cracks, or simply replacing them with new fuses would be a good approach and inexpensive.
Other than that it would have to be the control switch for the blower speed located in control panel on the dash, or a loose connection in the wiring of the circuit from the fuses, to the relay, to the panel and to the motor and finally to a nearby ground point. That circuit tracing may be a bit more time consuming.
When it cuts out and then back in, does this happen no matter what speed the blower is set to run? If so, then I would not believe it is the switch, but rather a fuse. If it is speed-dependent, then I would suspect the switch.
Roland
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