Check your owner’s manual to see if it shows a blower relay is used on your vehicle, and if so, where it is located. They usually put a diagram where all the fuses and relays are and where they are located in that manual. You’d want to make sure that’s not the problem before doing anything else. Relays are common electrical components in cars that stick closed sometimes as they age. If that happened the blower might run all the time.
If I understand correctly the recommendation made by Nevada above – assuming the problem isn’t a relay – is the blower control module is faulty. That probably isn’t the same part as the “blower resistor”.
Tester said above "In the under hood fuse/relay box, remove fuse 3, 30 amp and see if the blower motor stops operating. This fuse is hot all the time and supplies power to the contacts for high speed blower motor relay. If removing this fuse prevents the blower motor from operating, replace the high speed blower motor relay. Anyone know where that relay is?
I did run a test on terminal B which plugs into the resistor and is supposed to regulate the voltage passed along to the blower motor. It did not vary from 9 volts as the fan speed was adjusted inside the vehicle at the climate control panel as described in test 3 of this article.
I’m not familiar with the specifics of how Buick does it, but on all my cars where I’ve diy’er fixed the blower motor function, the “resistor” is actually a network of resistors. The fan speed switch switches from among them to insert a known resistance in series with the motor for that fan speed selection. The result is the available electrical power is shared between the blower motor and the resistor. For “high” speed, the full battery voltage is applied to the blower motor, so all the power goes to the motor, and it spins as fast as it can. For “medium” and “lo” speeds, more of the power goes to the resistor and less to the motor, causing the voltage to the motor to be less than full battery voltage, so the motor rotates less swiftly.
So if you are measuring the voltage applied to the motor, it should vary as you change the speed selector. If it doesn’t the resistor network may be faulty. But the problem is that usually when that happens the symptom is one or more of the fan speeds produces no fan action at all. Usually it is the lowest fan speeds that fails first, b/c that’s the one where most of the power goes to the resistor and least to the motor. The resistor for the low fan speed heats up hotter, so is the first to fail. And it almost always fails as an open, which prevents the fan from turning at all on that speed. Your symptom is different from that, so if the problem is the resistor network, it’s an usual failure mode.
I should say at this point the low blower speed on my Corolla failed on year three, and my solution to that is to use “medium” instead … lol …
One extra point: As part of this diagnosis, you should verify the blower motor spins freely and the blower cage it rotates also moves freely, no leaves or debris caught in there. The reason is that if those parts are not moving freely it can cause an over-current condition which could cause this problem to repeat itself after you buy whatever replacement part you decide you need to buy and fix it. You don’t want to buy the replacement part only to have it fail in a month b/c the blower motor isn’t spinning freely.
As others have been trying to tell you about this trouble; since you have climate control you most likely have a variable speed blower control, not just a switch for a few speeds. This type of circuit uses a solid state transistor module to control the blower motor current for the blower speed. The module is in series with the battery power to the motor so if the module fails in the shorted condition then power goes on to the blower motor and it stays on at all times. If it fails open than the blower doesn’t work at all. It is a common problem and either condition can happen. Before replacing the bad module with a new one the blower motor current should be checked to make sure the motor isn’t drawing excessive current that could damage the new module over time.
helped to replace in my 1993 Buick Park avenue but when finished no electric to any part of vehicle from battery. no lights etc. can anyone suggest trouble shoot procedure? had to remove fuse block under hood to get to blower control module in blower duct assembly. is anything now disconnected? Thanks Steve
You may have blown out a fusible link while working on things. Get a test light probe and check for power from the battery to the main panel under the hood.