Car heater intermittently works?

Hi,

Wow, that cold already? We need to get this working. I have a question. Do you mean the blower motor (fan) only works from time to time or is the vehicle only producing heat from time to time?

If it is the blower motor, there are a few things that can cause it. For example, the blower motor itself may be failing. Also, there is a blower motor resistor that may be faulty, but that should still allow the unit to work at high speed.

The one thing that I feel (in theory) that may be an issue is the blower motor relay. The relay itself can be failing.

I attached a pic below showing the relay location and what it looks like. See if you can locate it under the dash near the blower motor. You can test it or try replacing it. It shouldn't be expensive. If you want to test it, here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Also, do me a big favor. Check the connector at the blower motor and resister for any indication of overheating.

Let me know if this helps or if you have other questions. Also, pic 2 shows all three things to inspect. The FET functions as the resister and is responsible for fan speed.

Take care,

joe

see pics below.

Hi,

Is it the blower motor itself? If it is, then yes it could be related to temperature. When metal gets cold, it contracts. In the summer when it's hot, it will expand. If there is a connection issue or issue within the relay, it may cause this to happen.

Check the connectors first and make sure they are tight, not corroded, and there is no evidence of overheating (plastic that looks melted).

Let me know what you find.

Joe

Hi,

You could use a test light to check for power and ground. When you check for continuity to ground, connect the test light alligator clip to the battery-positive terminal. If there is a ground path present, the light will turn on. When checking for power, connect the alligator clip to the battery ground.

Let me know.

Joe

Hi,

If you have repaired the wiring and it is clean, tight, and not damaged, the motor is my first suspect. Fortunately, it is an easy one to replace.

I don't know if you need them, but I attached the directions below.

Let me know if that helps.

Take care,

joe

See pics below.