The blower would only work if the blue was hooked to the on-auto switch.Now the new motor has locked up.The blower relay has 4 wires from the t-stat, could this be the problem?Thanks in advance

I replaced the blower motor,now the blower only works if the a/c is off and turn the switch to on instead of auto,or if I unplug the connector directly behind the switch.Thanks in advance for your help