Blower motor draining battery

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El Paso
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Lewis
Truck Year
1977
Truck Model
K10
Engine Size
350
When i plug the connector into the blower motor it drains the battery overnight.
Any suggestions?

77 k10
 

fast 99

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Shouldn't be power on it with ignition off. There is another recent thread on how to trace draws.
 

75gmck25

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Northern Virginia
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Bruce
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1975
Truck Model
K25 Camper Special TH350 NP203
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5.7
The blower motor relay has a direct (fused) power lead that runs from the junction near the brake booster, across the top of the firewall to the relay. That relay is only activated when the blower is on high speed or the A/C is on max. However, if the relay was bad, it might draw power when the ignition is off.
 

fast 99

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350
Some years fan ran on low to pressurize the cab but only when key is on. Might be a problem with that circuit. If the fan is running the draw should be high enough to power a test light. Backtrack from blower motor. First thing I would do is pull fuses to find out what circuit is powered up.
 

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