Blower motor receives it power from the ignition switch so it should not "directly" affect the operation of the OVP relay or the fuel pump relay.

However, a bad blower motor can draw a lot of current from the battery/alternator system and if they are not able to supply the current for whatever reason, the voltage at the battery terminal could drop substantially, and this would cause the car to stop.

So first, check the battery voltage when the blower motor is switched on, right before the car quits. If the battery voltage is o.k., check the voltage at a point which is after the ignition switch (e.g. some place in the fusebox). It is possible that some problem is occuring because the ignition switch has to pass this excessive current. It is though a little puzzling that your blower fuse is not blowing in this situation.

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Saumil S. Patel