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heater blower not working[ [another one]

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need some help cos this is confusing me, i have bought a new heater blower motor and switch, i have power to the wires that connect to the motor now but when i connect them to the motor there is no power, if i connect a multi meter to the spade connectors there is nothing but as soon as i disconnect the earth wire on motor and then put meter on with power wire still connected and meter earthed through wiring loom earth i have 12.2 volts again. i have even tried putting another earth from motor direct to battery but nothing. could i have an issue with the resistor in front of the motor.
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Resistor only for speeds 1 and 2 so try on 3, to see if that works.

Dan

1983 Cabby Gti All White Edition
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thanks i will try tomorrow, i just cannot work out why i have power to wiring loom point but as soon as i connect the fan there is nothing showing on multi meter.
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I've got same problem with my reverse lights, test it with multi-meter and shows power, then when I put bulb in nothing. Very confusing as all the other lights work off the same clusters.

Dan

1983 Cabby Gti All White Edition
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why do we persist eh ? had mine three years now and i am nearly certifiable, but cannot let it go.:'(
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They do like to test us, funny thing was after a couple of hours mucking about the other week and not really doing anything noticable to fix them they started working and when I went to replace one of the bulbs, stopped again and I can't get going again. Dam annoying as theres power there.

 

1983 Cabby Gti All White Edition
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i do get a bit annoyed with mine but i know as soon as roof comes off then all is forgiven. i have called it quits with temp gauge though it works one minute then gives up.
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Remember Volts doesn't tell the whole story.

You can have 12 or 13 volts, but hardly any amps.

I don't know how much a heater motor draws, but I would guess it's around 10amps at 12 volts, maybe 15.

Have you checked the fuses, to make sure there not just not blown, but the are the correct amperage?

Also, run a positive wire to the feed spade and a negative wire to the earth connection of the motor from a known source, like the battery, to make sure all is well with the motor. (could set the whole lot up on a bench with switch and resisistor first)

You may just have a burnt out wire, poor connection or a broken cable. Could even be a poor connection the fuse board.


If you want the PSD Boot Sticker file, it's here: Boot Sticker
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thanks for the ideas, i have hard wired it straight to battery so i know that the fan motor does work, not sure how a fuse could be gone if i have a good power reading at multi meter from wiring loom though, would that not prove i have a good power source and a good earth.
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It may be that the power reading is OK on the Volts side, but not enough on the amps side. It's worth just substituting the fuse anyway, just so you can 100% rule it out. Simple things first.

If the amps are low, it won't work. Imagine if the starter motor wire had a 5 amp wire running to it. It would have 12 volts, but not enough of that 12volts to turn the starter.  Its the difference between flow and pressure, like turning on a tap, if there's plenty of flow, but not enough pressure, the bath takes longer to fill.

Have you got an Ammeter on your multi meter?
Also, you can try the feed wires to the motor on a bulb, to see if it lights and how bright it gets, as a rough indicator.

Have you checked the resistances on the heater rheostat?

If you want the PSD Boot Sticker file, it's here: Boot Sticker
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that seems to be getting a bit technical for me, i can gheck for volts but not sure about amps. are you saying i might be best re-wiring from the loom to the resistor and changing the relative fuse. how do i go about checking the resistance from the reistor.
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Have a google about using a mulitmeter, i'm not so clever when it comes to auto electrics (hence my ongoing problem, but more weather stopping me from sorting it than anything else at the moment), but there are quite a few sites than run through which setting you need to put the meter on for testing different things, quite handy if your not that electrically minded.

Dan

1983 Cabby Gti All White Edition
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will have a look at that ta.
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I will try and do a quick 'how to' a little later when I get a minute. You'll be surprised how easy it is.

If you want the PSD Boot Sticker file, it's here: Boot Sticker
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that would be fantastic thank you.
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Okay, to make this as painless as possible, it will take a little time. I'm working in the morning, so will get around to this a little later.

I have some info already, but first I need to know what year your car is, then we can get the correct wiring diagram, and I can use that to explain how and what to test.

UPDATE…So far I've found 3 different systems of wiring with the 3 position switch type, so if you could give me the model year, I can get to work on a guide.

Just as a matter of interest, 2 of the diagrams show the glove box light taking the feed from the same place as the heater fan motor (S14, 20amp). Does yours have a glove box light? and if so does it work?

Ta.

Last edit: by Longimanus


If you want the PSD Boot Sticker file, it's here: Boot Sticker
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it works:thumbs:  have spent most of day on car, took a resistor off brother in laws mk1 tin top, no luck so started looking around fuse box, then i found a grey and yellow wire with a male and a female connector, the female was placed onto a spade on fuse box but the male end was just hanging around,  so put them both togather as they looked pretty good together and hey ho it blows like a good un, thanks for all the help from you guys it is appreciated and i hope maybe my results might help  someone else with a problem like this, now got to finish fitting my new ignition cos i have had to remove my steering column to get housing off, keep going eh.
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 Well done! The wiring diagrams I found had that colour wiring on. Glad you got it sorted.

Mine's overheating the switch, so I guess I will be replacing the resistor or motor soon to!

If you want the PSD Boot Sticker file, it's here: Boot Sticker
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