HVAC Trouble Code 9???

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Sep 12, 2019 | 08:38 AM

Josh Brown

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From: South GA

HVAC Trouble Code 9???

Ive got a pretty 1989 Corvette, with the climate control digital display HVAC controls. The Ext temp light flashes for the first minute, and nothing works, then after 1 minute, everything works perfectly. Not really a problem just a nuisance.
I read the codes following the instructions, and under the diagnostics number, it came up with code 09.... 09 doesn't come up with any results in all my searches for an 89 model. Any additional guidance is appreciated.
Just for fun I checked the A/C pressures and all looked in spec, and the AC works fine. Im sure its some sensor, but dont know what code 09 points to.

Sep 12, 2019 | 02:09 PM

billschroeder5842

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09 is "low freon"

Sep 12, 2019 | 02:53 PM

Josh Brown

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I checked the pressures, and all looked good, and it blows very cold no problem. Could it be just the sensor? Any idea how to test it like what the resistance or voltage should be? Can I disconnect to see if that fixes it?

Sep 16, 2019 | 08:11 AM

Josh Brown

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No Help?

I thought the trouble code 9, mixed with the not working for 1 minute consistently, then working perfectly would tip someone off that had the problem before.

Sep 18, 2019 | 08:08 AM

Josh Brown

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One more bump. Still no answer. Im sure its some other sensor, but cant figure it out. Everything works fine after 1 minute, the Ext temp stops blinking, all good.

Sep 18, 2019 | 10:09 AM

pcolt94

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Quote:

Originally Posted by Josh Brown

Measuring pressures is the proper way to check first. But it does not tell you how much Freon is in the system and the system operates much different driving compared to standing still and checking.

Code 9 is low Freon. The code is set when the compressor ON time is too short. In other words it is cycling too much. This usually indicates low Freon if everything else is working OK. You might consider adding a few ounces of Freon and see if that makes a difference.

You might see the code 9 occur more at the cooler ambient temperatures.

** As an after thought, sounds like you have a set of gauges. At what pressure does the compressor drop out ( should be around 22.5) and what pressure does it re-engage (should be around 46). This would ensure the cycling switch is basically OK.

Last edited by pcolt94; Sep 18, 2019 at 10:23 AM.

Sep 20, 2019 | 04:05 PM

Josh Brown

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Thanks for the reply. After the 1 minute of code 9, everything works flawlessly. Compressor runs all the time. Stays at 30psi on the low side. Doesn't drop or turn off. It's just as soon as I turn the key on, its throwing a code. Gotta be something electrical, not the low side switch. Jumped it already.

Mar 2, 2021 | 10:45 PM

Josh Brown

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So as an update for the future person searching. The issue was the stuck blend door. It would throw the code on the HVAC system for 1 minute while trying to move. The system would then just give up and throw the code and allow it to run normally. Never did fix it just dealt with the heat for 1 min.