EATC and Max AC

new 6/07/2004

Hi all,
I've not seen this in the FAQ so here goes:

According to the manual, the Max AC function will display 60° and Max AC. I don't know if it will run the fan at max like other systems and mine doesn't. It does show "Max AC" but the temp does not change from my Auto setting. It also continues pulling outside air through the filter (I just changed it) but does do some "shifting" down under the dash.

Before I get into this further, has this occurred before to anyone and what was the cause? Do I need to shop for footballs?

Thank you for your help. My 97 is running perfectly and I'm starting to nit pick. AC is perfectly cold otherwise.

Marc
97TR, Atlanta

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Self Test

1. NOTE: Intermittent (run time) trouble codes will be deleted after 80 ignition cycles.

The remote climate control module is capable of displaying both self-test faults and intermittent (run time) faults on the integrated control panel. To obtain these codes, perform the following EATC on-board diagnostics test:

On-board diagnostics should be run in ambient temperatures between 10° C (50°F) and 32°C (90° F). Record all diagnostic trouble codes (DTCs) displayed during diagnostic test mode.
Turn ignition switch to RUN position.
Push both OFF and FLOOR buttons simultaneously, then press AUTO within two seconds.
The test may run as long as 30 seconds while the display will show a dashed line in the center of the display window.
After about 20 seconds, a DTC will appear in the display. Refer to the Diagnostic Trouble Code Index to identify the proper diagnostic procedures.

Diagnostic Trouble Code Index
EATC On-Board Diagnostics		New Generation Star Tester or Service Bay Diagnostic System DTC	Description	Action
Self-Test Faults	(Inter- mittent) Run Time Faults		Description	Action
	022	B1239	A/C Electronic Blend Door Actuator Short.	GO to Pinpoint Test A .
024	025	B1249	A/C Electronic Blend Door Actuator Failure.	GO to Pinpoint Test A .
031		B1251	In-Car Temperature Sensor Open	GO to Pinpoint Test B .
030		B1253	In-Car Temperature Sensor Short.	GO to Pinpoint Test B .
041	043	B1255	Ambient Temperature Sensor Open	GO to Pinpoint Test C .
040	042	B1257	Ambient Temperature Sensor Short	GO to Pinpoint Test C .
050	052	B1261	Sunload Sensor Short	GO to Pinpoint Test D .
	195	C2767, U2005	Communication Error Between ICP and RCC	GO to DTC U2005.
	115	U1073	Engine Coolant Temperature Signal	Refer to the Powertrain Control/Emissions Diagnosis Manual.
	125	U1341	Vehicle Speed Signal	Refer to the Powertrain Control/Emissions Diagnosis Manual.

To exit the diagnostic test mode, press the blue button. When the EATC system assembly is turned back on, the A/C air temperature control door will self-calibrate for 20 seconds.

2. If self-test is passed and no DTCs are retrieved, go to Symptom Chart to continue diagnostics.

3. If DTCs are retrieved, go to the Diagnostic Trouble Code Index to continue diagnostics.

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6/08/2004

Okay, I found the EATC spec here at work.

Control Assembly Selection

A/C Air Temperature Control Door Response

Heater Air Damper Door Response

Windshield Defroster Door Response

Heater and A/C Air Inlet Duct Door Response

Heater Blower Motor Response (Unless Manually Overridden)

A/C Clutch Response ^a

Max A/C

Varies according to sensor temperatures and customer temperature selection.

Air to heater air plenum chamber.

Fixed in panel position.

Fixed in recirc position.

Variable A/C blower motor speeds.

A/C clutch on if outside temperature is above 10°C (50° F).

So, basically, pressing MAX A/C is really just a recirculation AC button. It still accepts temperature input from the driver, and is actually a variable fan speed. The only things that are immutable are the door settings, which blow it on the front vents only, and the AC clutch, which would only disengage under WOT, but would not cycle otherwise.

Personally, I'd rather have independent recirc and A/C clutch buttons, but such is not the case with the '97 EATC.

-John Breen III

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