Re: Under dash A/C blower motor added a relay
The problem is, most people end up using relays as a 'crutch'. Instead of solving why there is a low voltage situation.
For example, 12.8 volts at the horn relay with the engine running is too low and indicates there are wiring/charging issues.
The reason modern vehicles use so many relays is the controls on virtually item is dictated by the BCM, PCM etc. These modules are only capable on sinking or sourcing (providing a ground or positive out) a small amount of current that could not "drive" things like lamps, starter solenoids, fans, etc. They can however, drive relay coils directly, and of course the relays do the "heavy lifting" to provide the large current paths to the vehicle devices.
-If you don't stand for something, you'll fall for anything.