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Blower motor - how to distinguish positive/negative terminals?

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13 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
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YOUR RESEARCHBlower motor - how to distinguish positive/negative terminals?

Leading reported evidence

Replace within 15 minutes

Performed · outcome unconfirmed

No successful repair reported for this finding.

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Performed · outcome unconfirmed · Original poster

Replaced within 15 minutes.

Blower motor - how to distinguish positive/negative terminals?
Frequently discussed work

Check of the fan

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Suggestion

Therefore, a simple polarity check of the fan using 12V +/- would determine the correct fan rotation and thus, point to the correct terminals?

Blower motor - how to distinguish positive/negative terminals?
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Leading evidence: 'Replace within 15 minutes' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check of the fan' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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Check of the fan

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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.

Discussions that contain suggestions
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

Therefore, a simple polarity check of the fan using 12V +/- would determine the correct fan rotation and thus, point to the correct terminals?

Blower motor - how to distinguish positive/negative terminals?

Test wiring connection, make darn sure you enable the fan

Suggestion or failed attempt

No successful repair reported for this finding.

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Reported fixes
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Unsuccessful attempts
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Discussions
Read evidence and context

Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.

Discussions that contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

If you are going to bench test the wiring connection, make darn sure you enable the fan to spin freely.

Blower motor - how to distinguish positive/negative terminals?
Frequently discussed actions (3)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Check of the fan

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

Therefore, a simple polarity check of the fan using 12V +/- would determine the correct fan rotation and thus, point to the correct terminals?

Blower motor - how to distinguish positive/negative terminals?

Replace within 15 minutes

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed · Original poster

Replaced within 15 minutes.

Blower motor - how to distinguish positive/negative terminals?

Test wiring connection, make darn sure you enable the fan

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

If you are going to bench test the wiring connection, make darn sure you enable the fan to spin freely.

Blower motor - how to distinguish positive/negative terminals?
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Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.

13 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

  • Rennlist: 1 discussions

0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.

0 acknowledgements have no verified action link; they do not establish a repair result.

Generation: 20261026T135432Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1 / ORIGINAL POSTEROriginal post

My blower motor from my 2000 C2 cab failed, while I got a replacement, I realised my original blower motor was from older year parts. The problem is that older motor has a wider plug (lower) and the post-2000 motor has a smaller plug (upper). I had to buy a plug again (below) and now my question is: How do I determine where should the positive wire goes to? Both the original wires are black and I couldn't tell which is which. Or, does it make any difference at all? Hope someone could help. Thanks a million.

POST 2Original post

Trial and error is fine; you won't hurt anything. If you connect the wires backwards the motor will just spin the wrong way, and then you'll know you need to reverse the wires. Just hook it up temporarily with bare wires before making your final crimp/solder connections.

POST 3 / ORIGINAL POSTEROriginal post

Quotes source post: 15220483

Thanks for shedding some lights, and the tips about the bare wire part. Will try this weekend.

POST 4Original post

If you are going to bench test the wiring connection, make darn sure you enable the fan to spin freely. I could just see connecting the wires while it is sitting on the bench and having that thing go flying!

POST 5 / ORIGINAL POSTEROriginal post

Quotes source post: 15220789

Lol! Thanks Joe, this is a very practical tip indeed.

POST 6Original post

Since these are consider "purge" fans, wouldn't the air need to be blowing up and out of the engine compartment? Therefore, a simple polarity check of the fan using 12V +/- would determine the correct fan rotation and thus, point to the correct terminals?

POST 7Original post

The engine lid fan blows air into the engine compartment. I believe what he is working on is the HVAC blower motor in the cabin.

POST 8Original post

Quotes source post: 15220891

Hi. Not trying to be contentious, but why would it be called a "purge fan" if it's pulling air into the engine compartment? This is not a radiator fan, right? I thought the premise behind the purge fan is that it serves to "delete" or "purge" hot air. Seems like I remember the manual saying that as well. Thanks for correcting me. I have a lot to learn.

POST 9Original post

Is this the rear spoiler blower? The plug should be labled "a-b" or similar. Post your current wire colors and ill see if there is a difference. In the bentley book: For 2002 and 2004 it shows b- rd/bk, a- bn For 1999 its the same but b- br, i think both r considred brown b is power from the relay, a is ground. u will need to get the magnifier out and fing the lable on the connectors

POST 10 / ORIGINAL POSTEROriginal post

HVAC blower motor was talking about. Sorry for notaking it clear 😉

POST 11Original post

Ok ill try to remember to look up the hvac blower when i get home tonight.

POST 12Original post

So that plug in 99 should be labled 1 and 2, 1 is power from the blower resister and 2 goes to ground. 2002 and 2004 both show a 4 wire plug if im reading the book correctly i would find the number labels on the 2 plugs and wire them the same.

POST 13 / ORIGINAL POSTEROriginal post

Quotes source post: 15224509

Thanks for this. I could see the 1 and 2 and had no idea what do they mean before. I managed to trace the 1, and I could see the brown cable. Then I could see a brown cable inside the new motor and figured out where should the +ve goes to without hesitation. Replaced within 15 minutes. I also took out the passenger airbag to make room for me to fix the front speakers that dropped out from the mount, rerun the wires and it now looks very neat. ​​​​​​

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