my ac/heater fan comes on randomly so I checked relay by swapping with ignition relay(exact same) and at that point car will not turn over but fan comes on instantly. So I purchase new relay and have same issues,at that point I swap again just to double check issue and same results(one will work then other after swapped but both will not work at same time). So I think I was sold a bad relay so I go back to auto zone and they give me another one. Still same issue so at this point I try O'Reilly and again same results. Is it possible all 3 were bad relays or am I missing something else that could cause this?? I am baffled and do not understand, please help
My car has 122000 miles.
My car has an automatic transmission.
The relay can be tested with a volt ohmmeter and a 12 volt power source. Once you have a known good relay, if the blower doesn’t work when you command it on, what a mechanic would do is simply trace the circuit (using the factory wiring diagram) to pinpoint the interruption. In your circumstance you could have a blower motor with a defect in the armature (will cause intermittent operation) or a loose ground or loose terminal connection. If you trace the circuit, you are guaranteed to find the interruption though and in your case it almost undoubtedly does not involve the relay. If you want the circuit trace performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an electrical circuit/component diagnostic and the responding certified mechanic will get this resolved for you promptly. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.
Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing