Blower motor won't turn off

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Charlie7985

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Charlie
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I recently rebuilt my entire a/c system. At first when a/c was running I had a constant fog horn type noise that appeared to be coming from the blower motor relay. I replaced the relay which was new and it would also do it intermittently. Replaced again with a different brand and would make the noise intermittently again. The other day it quit blowing at all. I found that the wire going from the capacitor to the blower motor was melted in some places. Part of the plug on the relay was also slightly melted at the brown wire connection. I replaced the relay again and bypassed the capacitor. Same noise and blower won't turn off even when the key is off. What gives?

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wanderinthru

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Check your voltage going to the relay from the switch in the cab? My bet is the problem is the cab switch.?? This all comes from me taking one of those relays apart, and the best way I could figure it works is the speed control switch in the cab sends a different voltage at each setting? Did the blower change speeds, or just run wide open?
 

Matt69olds

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Replace the blower motor, it’s probably drawing an excessive amount of current. Unless you have a meter than will handle a 25plus amp spike, it’s hard to test the motor.

The melted connector is a classic symptom of excessive current draw. The motor may take 25-30 amps at startup, but shouldn’t draw more than about half that once it’s going. The constant high current isn’t enough to pop the fuse, but is more than enough to get the wiring pretty toasty.

Clean and polish all the terminals, once they are shiny clean give them a light coating of dielectric grease.
 

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