HVAC question
Thread Starter
Burning Brakes
Joined: Nov 2003
Posts: 935
Likes: 2
From: Beverly, NJ
HVAC question
My 86 vette couple just developed a problem where when I shut the car off and pull the key out, the blower motor keeps running. Also when the car is running and I press the off button on the HVAC control, it also continues to run. I have the digital HVAC control. Any idea what my problem could be? Thank you in advance.
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From: So. Cal.
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vette
My 86 vette couple just developed a problem where when I shut the car off and pull the key out, the blower motor keeps running. Also when the car is running and I press the off button on the HVAC control, it also continues to run. I have the digital HVAC control. Any idea what my problem could be? Thank you in advance.
Also check grounds?
Good Luck
Corvette Mike
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Blower control module is cactus.
Is a electronic relay that supplies power direct from battery to fan controlled by head unit.When it is faulty allows power to fan with no control.Will sometimes operate at random. Freaky when you are alone in garage and fan starts by itself!
Is mounted inside the AC ducting on engine side of firewall.2 large plugs on plate held by 3 8mm screws.
Temp;
disconnect the blower motor connector to prevent battery running flat.
Is a electronic relay that supplies power direct from battery to fan controlled by head unit.When it is faulty allows power to fan with no control.Will sometimes operate at random. Freaky when you are alone in garage and fan starts by itself!
Is mounted inside the AC ducting on engine side of firewall.2 large plugs on plate held by 3 8mm screws.
Temp;
disconnect the blower motor connector to prevent battery running flat.
Last edited by rodj; Jun 1, 2009 at 08:31 PM.
Team Owner
Joined: Jan 2003
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From: Summerland B.C. Canada
Pro
Joined: Mar 2008
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From: High Bridge New Jersey
Possibly
My 86 vette couple just developed a problem where when I shut the car off and pull the key out, the blower motor keeps running. Also when the car is running and I press the off button on the HVAC control, it also continues to run. I have the digital HVAC control. Any idea what my problem could be? Thank you in advance.
Corvette Enthusiast
Joined: Oct 2007
Posts: 6,790
Likes: 2,696
From: So. Cal.
2025 C7 of the Year Finalist- Unmodified
2024 C7 of the Year Finalist - Unmodified
2023 C7 of the Year Finalist - Unmodified
Rodj
Blower control module is cactus.
Is a electronic relay that supplies power direct from battery to fan controlled by head unit.When it is faulty allows power to fan with no control.Will sometimes operate at random. Freaky when you are alone in garage and fan starts by itself!
Is mounted inside the AC ducting on engine side of firewall.2 large plugs on plate held by 3 8mm screws.
Temp;
disconnect the blower motor connector to prevent battery running flat.
Is a electronic relay that supplies power direct from battery to fan controlled by head unit.When it is faulty allows power to fan with no control.Will sometimes operate at random. Freaky when you are alone in garage and fan starts by itself!
Is mounted inside the AC ducting on engine side of firewall.2 large plugs on plate held by 3 8mm screws.
Temp;
disconnect the blower motor connector to prevent battery running flat.
Corvette Mike
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Electronic A/C Module is not a Relay but an amplifier that accepts low voltage inputs from the Dash Controls and ramps them up to run the Blower. And yes, when it fails, the fan can run with the ignition off, but that can also happen if the fused circuit returning actual blower voltage to the Controller opens. The fuse - 5 amps - is on the Firewall and it's leads will be the same color as the Blower hot wire - that's generally black/red for an '86. In '88, GM switched it to Purple. Anyway, check the fuse first.
Also, through '89, Module is a switched ground for the compressor. After that, PCM controls compressor engagement and the Module is only for the Blower. However, the Dilbert's who designed it left in the feature that will cause the Blower to run with the ignition off; ie, if the 5 amp fuse on the monitoring circuit opens (now moved to the fuse box) or if the Module shorts, it'll spin the fan on Max, key off.
Also, through '89, Module is a switched ground for the compressor. After that, PCM controls compressor engagement and the Module is only for the Blower. However, the Dilbert's who designed it left in the feature that will cause the Blower to run with the ignition off; ie, if the 5 amp fuse on the monitoring circuit opens (now moved to the fuse box) or if the Module shorts, it'll spin the fan on Max, key off.
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