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Help! Hot engine air conditioning off

blk99cpe

New member
Joined
Jan 5, 2004
Messages
4
Location
PA
Corvette
1999 Black Coupe
Hello,

First time poster looking for some help with my 2006 Vert...

I recently had my car in to upgrade the Edelbrock Eforce SC that was installed back in May 2012. Everything had been fine up until this point.
The upgrade was the fuel pump upgrade pulley swap to get a few extra HP, because 554HP wasn't enough ;). Actually I was having an issue with the fuel gauge so after trying the Techron fix (and it not resolving the issue), I decided to have the tanks dropped and replace the fuel sending units, and while the tanks were down, why not have this upgrade done at the same time. Fuel gauge works fine now...

Now to the problem.

Only on cold starts (after the car sits overnight), do I have an issue where the car idles high, starts to come down to normal rev levels, then I receive the Hot Engine Air Conditioning Off error. I was able to read a P0116 from my SCT Tuner that came with the SC kit and based on that the Coolant Temperature Sensor was replaced. The analog / digital displays for the coolant are not registering while this error exists. I had also read that a faulty thermostat could cause this issue, so I asked the mechanic to replace that when the sensor didn't resolve the issue. If I let the car run with that initial error, it idles extremely rough and there is a gas smell coming from the exhaust.

If I turn off the car and use the SCT Tuner to clear the error codes, the car starts fine and I can drive it without issue. Coolant temperature displays normally. I can also turn the car off for some time and start it up without issue. It's only after the car sits overnight, that I receive the error and have to go through the process to clear codes to get the car to start up and run properly.

What is the difference between the car starting up after sitting overnight vs. a 'warm' startup?

I reached out to Edelbrock to see if they had seen this issue before, but they hadn't and stated that the tune for the SC (I had downloaded the latest updates from their site) would not cause this issue.

My mechanic is also researching this issue, so hopefully between the 2 of us (and everyone we reach out to) we can get this one solved and I can enjoy the summer weather in my car.

Recent changes to car:
Coolant Sensor
Stock Thermostat
New battery and starter installed last year (battery replaced earlier this year under warranty after issue started to appear)

Any help is greatly appreciated.

Kurt
 

redvett

Well-known member
Joined
Dec 16, 2001
Messages
486
Location
AZ
Corvette
2001 Convertible
Its obviously the coolant temp sender or programming issue, try using the old CTS.
 

blk99cpe

New member
Joined
Jan 5, 2004
Messages
4
Location
PA
Corvette
1999 Black Coupe
I'll pass that on to my mechanic and post any updates. Thanks for the reply.


Sent from my iPhone using Tapatalk
 

blk99cpe

New member
Joined
Jan 5, 2004
Messages
4
Location
PA
Corvette
1999 Black Coupe
More info:

HVAC module reads actual ambient temp correctly and displays correctly.

BCM has RPO code for manual A/C C68, but should be CJ2. Unable to change with Tech2 scanner or GM Tis

PCM reads -22 degrees F

Ambient temp sensor and circuit have been verified.

Coolant temp sensor and circuit have been verified.





Sent from my iPhone using Tapatalk
 

redvett

Well-known member
Joined
Dec 16, 2001
Messages
486
Location
AZ
Corvette
2001 Convertible
Change the CTS since tyhe PCM reads -22 degrees F should read 195F+ when engine is running at operating temp.

C 68 Is HVAC SYSTEM,AIR CONDITIONER FRT AUTO,ELECTRONIC. (Right from GM RPO book.)
You have the correct calibrations for Auto Air.

Looks like all your problems is the CTS, use a new OEM sensor.

More info:

HVAC module reads actual ambient temp correctly and displays correctly.

BCM has RPO code for manual A/C C68, but should be CJ2. Unable to change with Tech2 scanner or GM Tis

PCM reads -22 degrees F

Ambient temp sensor and circuit have been verified.

Coolant temp sensor and circuit have been verified.





Sent from my iPhone using Tapatalk
 

blk99cpe

New member
Joined
Jan 5, 2004
Messages
4
Location
PA
Corvette
1999 Black Coupe
Issue Resolved

Just wanted to provide an update on this, which seems to be resolved now.

After further diagnosis and no resolution, my mechanic reached out to SCT Performance to confirm the tuning files that had been installed onto my car. It seems that there were 2 different sensor types used in the Edelbrock SC Kits and for some reason during one of the latest upgrades to the device (which was done as I wanted to make sure I had the latest tunes), it downloaded the tune for the wrong sensor.

The technician at SCT worked with my mechanic to get the proper tune installed to the device and reprogrammed the car's computer. Everything is working properly now, no issues at first startup. :happyanim:

Thanks for your help/feedback redvett!
 

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