This is the second time this has happened.

When I turned my car on this morning after it was sitting all night in my garage (about 80 degrees outside , no humidity), the A/C wouldn't work. Figured I would need to take the car in to be serviced-- but, about an hour later, after driving for about twenty minutes and stopping the car for about 40 minutes, start the car again, put on the A/C, and it works fine!!
Any ideas? I have dual climate control-- just assume that I was operating it properly./

 

Check the codes to see if there any set.
BC

 

If there are no codes on the DIC-- how do I check to see if there are any?

 

Obtaining Vehicle Codes from the DIC


The IPC display, the 20-character, vacuum florescent screen above the steering column that says "Corvette by Chevrolet" every time you turn on the key, is a powerful device. DIY Service Techs are going to be most interested in the IPC's ability to show diagnostic trouble codes (DTC) for all the modules that transmit them.

The "diagnostic display" mode is entered with the following procedure:

Turn on the ignition but don't start the engine.
Press the "reset" button to turn off any warning messages
Press and hold "options" and
While holding "options", press "fuel" four times within a 10-second period.

Inititially, the on-board diagnostics go into the "automatic" mode which shows each module's DTCs in a pre-set sequence:

10 PCM Powertrain Control Module page 6-357 - 6-361
28 TCS Traction Control system ABS on page 5-86
?? RTD Real Time damping page 3-136 (I do not have this option)
40 BCM Body Control Module page 8-405 UTD Page 8-727
60 IPC Instrument Panel Cluster page 8-508
80 radio page 8-213
99 HVAC Heater Vent-Air Conditioning page 1-118
A0 LDCM Left Door Control module page 8-904 to 8-951
A1 RDCM Right Door Control Module page 8-904 to 8-951
AC SCM Seat Control module page 8-1064 -8-1082
B0 RFA Remote Function Actuation page 8-676

For each module, all DTCs will be displayed. If none are present in a module, you will see "no more codes" on the ICP display.

There are two kinds of DTCs, "Current" and "History," designated with a letter suffix, "C" or "H". A current code indicates that the malfunction is present in the system whose module is displaying data. A history code indicates a problem existed in that module sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it is possible it's evidence of a previous problem, now solved, that was not removed by clearing codes. More likely is that a history code indicates an intermittent malfunction. "Intermittents" are the most challenging DTCs. An intermittent may have happened only once, may have happened more than once but is inconsistent in its appearance or may be happening on a regular basis but not at the time the IPC is displaying codes. History codes can also be caused by a current malfunction in a system that is not operating at the time DTCs are displayed. An example is the rear window defogger which doesn¹t operate until the BCM detects engine rpm. For history codes set by a system that does not operate with the key on and engine off, a special diagnostic tool called a "scan tester" is necessary to properly diagnose the malfunction.

Once the IPC has displayed all 11 modules, the system goes into the manual mode which allows selection of each module using combinations of DIC buttons. The manual mode can also be entered at any time during the automatic sequence by pressing any button except "E/M". Once the IPC displays "manual diagnostics," you may select a particular module by pressing the "options" button to go forward or the "trip" button to go back. Once a system is selected and a DTC is displayed, if more than one are present; press "gages" to move forward or "fuel" to go back.

To exit the diagnostic mode at any time, press "E/M". If you want to erase or "clear" codes, press "reset." Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory.

PLEASE let us know what codes you have in memory!

BC

 

When you say the AC wouldn't work, would the light on the AC button just blink for a few seconds when you hit it? What was the external temp shown on the display?

If the answer to the above questions is yes and less than 36F, the external temp sensor is likely the problem. Since the AC eventually turns on, it sounds like the sensor connector may have water in it and/or be corroded causing the sensor to send a false low temp to the unit, which prevents the AC from coming on.

Check the sensor and unplug it - the temp should default to a mid 50F temp that should allow the unit to work. If that's the problem, either clean the connector and sensor contacts or replace (fairly cheap).

 

Thanks---I'm going to check the codes.
The external sensor seems to be working properly-- It was reading 85 deg. all day yesterday.

 

Good post. One for the archives. This place rocks.

 

well, let's keep it out of the archives until I resolve the issue!
I'm out to LA for a week or so-- I'll check this when I get back.