91 Corolla heater

[red7d7]

Daughters heat wont work once the outside temp drops to 10 or below. Once outside temp rises and car is not so cold the heater will work fine. When it's that cold out she gets absolutely nothing at all fan will not go on at all. I am thinking this is a relay switch but am not sure where to locate it. Fan has no problems at all when I pulled it to check it out. When working everything works fine and gets plenty of heat no noise from the fan at all. Any ideas or knowledge of where to locate the relay would be appreciated.

[eberbs1]

I would check the blower motor resistor.
It is under the glove box and has 1 screw to hold it in and a 4 wire connection plugged into it. when its removed it has 4 springs on it, if any are broken it needs to be replaced. i can take some pictures if you cant find it.

[red7d7]

I have found the resistor, but could this cause the problem she is having? Everything workd fine once it warms up a bit outside. Once the outside temp drops to 10 degrees or below that it will not work.

[K Lea's ol Corolla]

Check for power at the 2 wires that plug into the motor. With the selector on hi, there should be a full 12 volts at the colored wire. Black is usually your ground.