What is a blower motor relay?
The relay is a switch that controls the blower motor. Basically, it tells the blower motor when to turn on and circulate temperature-controlled air in your car. If your car has a separate air conditioning unit (like a rear AC system), it has another blower motor and an additional relay.
Keep in mind: The blower motor relay is not a fuse. The relay is a control, while the fuse protects the relay from electrical power surges.
How do I know if my blower motor relay is bad?
You’ll probably have a pretty good idea that something is wrong with your car’s air conditioning system. Here are some of the most common symptoms of a bad blower motor relay:
Blower motor doesn’t work: If your AC system is suddenly wonky—it only works on certain settings, or it stops working entirely, the relay is likely bad. The point of contact may have worn out, or the relay could have gotten stuck. Either way, the climate control in your car won’t function as it should.
Blown fuses: This one is actually pretty easy to check as long as you know what you’re looking for. Pop the hood and check your fuse box for the blower motor fuse. If the filament is broken, the fuse is blown. This can happen if there’s been an electrical spike.
Melted relay: The relay can get hot if there’s something wrong with it. In extreme cases, the relays can overheat, and the plastic housing will melt or burn. If this happens, you might see damage to the car’s fuse box.
Keep in mind: A mechanic will diagnose a faulty relay by powering it to see if the relay clicks. Then, they’ll measure the resistance across the relay.
How often should a blower motor relay be replaced?
In general, blower motor relays need to be replaced every 60,000 to 100,000 miles. However, every manufacturer specifies an age or mileage limit for their blower motor relays, so check your owner’s manual or consult with a certified mechanic.
The blower motor relay is not regularly checked as part of any regular maintenance inspection. If you suspect the relay is failing, schedule a blower motor relay inspection.
Can I replace my blower motor relay myself?
If you’re confident with your mechanic DIY skills, and you’ve already got a garage stocked with tools, you can replace the blower motor switch. Doing the replacement yourself is a great way to avoid paying labor costs. Before you begin, read through your car’s owner’s manual, and follow all safety recommendations.
Warning: Don’t ever try to repair the damaged relay. It usually can’t be fixed, and the risk of damaging the entire relay is too high.