1987 Corvette AC Air Flow Problem

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May 24, 2015 | 02:26 PM

rikkilee vette

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From: Scottsdale AZ

1987 Corvette AC Air Flow Problem

I have a 1987 corvette with the digital dash. The auto button on the ac controller turns on the ac compressor and normally the ac air comes out of the front face vents. however now the air flow is also coming out of the defroster vent. This also happens with the econ button which is just the fan. It seems to be sharing about 50/50. Would anyone have an idea what could be causing this. The heater never has hot air coming out but has been blowing in the right direction. The main concern is the ac air flow as I'm in Phoenix (HOT). Any help would be much appreciated.
Thanks,
Rick

May 24, 2015 | 09:18 PM

Cliff Harris

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From: Anaheim CA

Prime symptom of a bad vacuum check valve. About $4 at any auto parts store. This is your guy:

May 25, 2015 | 12:52 PM

rikkilee vette

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From: Scottsdale AZ

I've located the check valve and will replace it. Sure can't complain about such a simple inexpensive fix. I'll let you know after I replace it.

Thanks Cliff,
Rick

Jun 8, 2015 | 02:27 PM

rikkilee vette

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From: Scottsdale AZ

Quote:

Originally Posted by Cliff Harris

Prime symptom of a bad vacuum check valve. About $4 at any auto parts store. This is your guy:

Hi Cliff, I replaced the Vacuum Check Valve with an ac Delco part and the problem still exists with the AC air split 50/50 between the defrost vent and the face vents. I thought I would ask where the next place to look for the problem would be. I hope it is not behind the dash. Thanks for your time on this.
Rick

Jun 8, 2015 | 05:33 PM

beerme

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From: Auburndale FL

Quote:

Originally Posted by rikkilee vette

Same problem, same year and model. I always assumed it is a weak vacuum connection because I changed my cam and I know the plastic vacuum line which is in the main wire harness broke so I patched it with a rubber line, again figuring this was better than nothing.

So based upon my experience I would recommend you check for vacuum leaks or a cracked vacuum line with in the main wire harness, and under the passenger side dash where another check valve connection exist.

Best of luck...

Jun 9, 2015 | 12:28 AM

Cliff Harris

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Joined: Apr 2002

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From: Anaheim CA

Quote:

Originally Posted by beerme

So based upon my experience I would recommend you check for vacuum leaks or a cracked vacuum line with in the main wire harness, and under the passenger side dash where another check valve connection exist.

That's just a connector to join the vacuum lines on the engine side to the vacuum lines in the cabin.