Blower motor draining battery

[Big red square]

When i plug the connector into the blower motor it drains the battery overnight.
Any suggestions?

77 k10

 

[fast 99]

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

 

[75gmck25]

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]

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.