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Old 03-01-2020, 10:25 PM
ddcrank ddcrank is offline
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Default Blower motor runs in off position

I have a 68 with A/C im not sure if i have a problem or not. The car has been a part for 20 years and im doing a complete restoration and i don't remember if the blower motor runs slowly even when blower switch is in off position? Blower only runs with key
in the on position or in Accessory position. When key is off blower does not run. Im pretty sure thats correct. Someone told me they thought a A/C car was supposed to have the blower motor run with the blower switch in the off position.I put a new switch in from Ames before i put the restored dash and gauges back in. Everything else works perfectly. I used M&H wiring harnesses they are all new. The blower motor runs with the blower switch in the off position it runs very low but it is running. So i put my original switch back in and same thing. Any thoughts or comments would be a great help.

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Old 03-02-2020, 01:50 AM
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hgerhardt hgerhardt is offline
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There is no "off" position on the blower switch. All the way down is low speed.

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Old 03-02-2020, 08:44 AM
ddcrank ddcrank is offline
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The switch has 4 positions OFF LOW MEDIUM and HIGH. All the positions work except OFF. In the OFF position the fan turns slower than in the LOW position.

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Old 03-02-2020, 10:34 AM
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Check the master relay and see if energized by the master switch. If so the blower will run at very low speed with blower switch off.

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Old 03-20-2020, 05:30 AM
Baron Von Zeppelin Baron Von Zeppelin is offline
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Quote:
Originally Posted by ddcrank View Post
The switch has 4 positions OFF LOW MEDIUM and HIGH. All the positions work except OFF. In the OFF position the fan turns slower than in the LOW position.
That is standard / correct.
GM did that for years, at least late 60's through late 70's.
Most never realize it though

Heard several explanations for it , but always thought they just anticipated selling more replacement blowers.

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Old 03-20-2020, 01:32 PM
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Quote:
Originally Posted by Baron Von Zeppelin View Post
That is standard / correct.
GM did that for years, at least late 60's through late 70's.
Most never realize it though

Heard several explanations for it , but always thought they just anticipated selling more replacement blowers.
It was to promote a minimum level of ventilation at all times; probably because most people smoked back then?

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Old 03-20-2020, 09:54 PM
ddcrank ddcrank is offline
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Thank you everyone for your input and for helping me figure out my issue. Im glad i dont really have a issue.

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Old 03-21-2020, 12:30 AM
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Stuck somewhere deep in my head - fan always running started on 1971 models on most if not all GM cars. Ptior to that, off was really off.

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Old 03-21-2020, 12:40 AM
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The reason the fan runs at slow speed is to keep air circulating in the air box to prevent mold/mildew from growing, especially in a car with A/C that is dropping moisture into the air box when the A/C is on. It also helps to keep the drain from blocking by drying the water up preventing mold spores from landing on the wet interior of the air box, sticking and growing on the wet surface.

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Old 03-21-2020, 01:16 AM
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I forget what vehicle it was, but some older vehicle I had, the slider for AC/HEAT/DEFROST had an OFF position .... the fan would keep running at low speed unless that slider was was set to OFF.

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Old 04-14-2020, 09:18 AM
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Quote:
Originally Posted by OG68 View Post
Check the master relay and see if energized by the master switch. If so the blower will run at very low speed with blower switch off.

Where is the master relay located?

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Old 04-14-2020, 02:32 PM
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I think it's a rectangular silver can bolted to the engine side of the firewall. About 1/3 the size of a pack of cigarettes.

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Old 02-06-2021, 09:23 AM
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Question Relay time.

I'm rewiring my 70's GTO to more modern standards , because these old electrical systems are giving me anxiety issues.

If I look at this diagram it looks to me that the blower switch is carrying the full grunt of electrical power the blower motor uses in the 'hi' setting.

Is it a simple fix to just put a relay between this ?

Or am I totally interpreting this wrong ?

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Old 02-06-2021, 10:37 AM
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The Brown wires under the 68 dash perplexed me.

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Old 02-06-2021, 01:05 PM
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My memory serves well that my 1968 LeMans AC car had the fan run in the lowest speed setting WHEN the Function switch was anywhere above OFF.

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