1995 Oldsmobile 98 battery drainage; parisitic battery loss

MRFELD

MEMBER
1995 OLDSMOBILE 98
6 CYL
FWD
AUTOMATIC
180,000 MILES

Battery drains overnight. Problem isolated to the the A/C circuit. The blower motor seems to function normal, however with the amp meter on the neg. Battery cable there was heavy amperage draw. If I unplug heater motor, draw stops. If I unplug fuse, draw stops. If I unplug resistor, draw stops. The connector for the resistor with one red wire is supplying 12V with car off & no key in ignition, which in turn goes from there to the heater motor with the car still off and no key. But here's the thing, at the red wire tested 12V, and when using a test light the bulb lights. At the blower motor tested 12V but would not light a test light. Are these readings normal? Should they have power w/o keys in ingition or does this indicate a problem w/ the motor or the resistor, or something else? Is it possible that this is what is causing my battery drain? How do I fix it?

4 Replies

INTERNETMECHANIC

MECHANIC
700 POSTS

How much amp draw? Use a digital voltmeter between the two terminals for the blower motor connector. With the key off, there shouldn't be any voltage at the connector. If your using a 12 volt test lite, there may be voltage, but not enough to turn on the lite, or if you were using chassis ground, maybe a poor ground. Use the connector wires for voltage and ground. Purple wire is voltage, black is ground.

Battery has a full charge and charging system works ok?