Why is the cabin blower motor relay buzzing?

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xirdneh
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My tercel:: 87 tercel 4x4 wagon w/reringed engine, 83 tercel 4x4 wagon w/salvaged engine and 4.1 Diff's
Location: seabeck, washington, USA

Why is the cabin blower motor relay buzzing?

Post by xirdneh » Mon Feb 19, 2018 3:42 pm

motor runs fine but relay buzzes.
removed passenger side panel to access relay.
replaced the relay and it buzzes too.
what would cause that?
Love those Tercell 4x4 wagons but they sure suffer from road noise.

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splatterdog
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Re: Why is the cabin blower motor relay buzzing?

Post by splatterdog » Mon Feb 19, 2018 4:45 pm

I would suspect a soon to be faulty connection at the blower switch. A small terminal in the switch turns on the relay and the rest of it controls ground after the motor. The only time I've had a dead blower was because of a broken wire at the switch, shutting the relay down.

A weird possibility might be the relay coil power is going thru the commutator bars of the motor.

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splatterdog
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Re: Why is the cabin blower motor relay buzzing?

Post by splatterdog » Mon Feb 19, 2018 6:10 pm

Actually looking at the diagram now, an alternate ground is not so weird. I bet the relay is getting ground thru the resistor, only during the moments between commutator bar contact in the running blower motor. Does the relay clicking change speeds along with the blower speeds?

I think you should focus on the switch and it's ground.

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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
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Re: Why is the cabin blower motor relay buzzing?

Post by Petros » Tue Feb 20, 2018 9:22 pm

you sure that is actually the blower relay? right in front of the blower is a little black cube that looks like a relay, but it is actually the door and key buzzer. I found it obnoxious and annoying so I removed it.

some how the buzzer got wired into the blower perhaps?
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

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