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Mike S.
Mike S., ASE Certified Technician
Category: Buick
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Experience:  A.S.E. certified
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2011 buick lacross blowing hot air when ac is on...scanned

Customer Question

2011 buick lacross blowing hot air when ac is on...scanned and found a code of b393b what do i do to fix this problem...
Submitted: 4 months ago.
Category: Buick
Expert:  Chad Farhat replied 4 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Expert:  Chad Farhat replied 4 months ago.

Let me look up the Fault code , that is A Body module fault , i ll be right back with you

ABS light on, traction light on , check engine light on at this time

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Customer: replied 4 months ago.
No
Expert:  Chad Farhat replied 4 months ago.

Usually that valve needs changing : Q46 Air Conditioning Compressor Valve.

I sent you the troubleshoot for the B393B, you will need a capable scanner to command ac on with it .

or you can do some testing manually, if no dealer scanner available .

i sent you also the description of the ac system operation

DTC B393B Diagnostic Instructions * Perform the Diagnostic System Check - Vehicle ( See: Vehicle > Initial Inspection and Diagnostic Overview > Diagnostic System Check - Vehicle) prior to using this diagnostic procedure. * Review Strategy Based Diagnosis ( See: Vehicle > Initial Inspection and Diagnostic Overview > Strategy Based Diagnosis) for an overview of the diagnostic approach. * Diagnostic Procedure Instructions ( See: Vehicle > Initial Inspection and Diagnostic Overview > Diagnostic Procedure Instructions) provides an overview of each diagnostic category. DTC Descriptor DTC B393B 04 - Air Conditioning Compressor Valve Control Circuit Open DTC B393B 0B - Air Conditioning Compressor Valve Control Circuit High Current Circuit/System Description The HVAC control module supplies battery voltage to the A/C compressor. When the A/C switch is pressed, the HVAC control module provides a pulse width modulation (PWM) signal to the A/C compressor in order to command the performance of the A/C compressor. The performance of the A/C compressor is regulated according to adjusted interior temperature on the basis of characteristic lines. Therefore the HVAC control module grounds the A/C compressor with the PWM signal. Conditions for Running the DTC * Ignition ON. * The HVAC control module is ON. Conditions for Setting the DTC B393B 04 A PWM greater than 10% is send out but no current is read back. B393B 0B Measured current is above threshold of 815 mA. Action Taken When the DTC Sets B393B 04 The A/C compressor is disabled. B393B 0B * The A/C compressor is disabled. * Output will be switched off for hardware protection. Conditions for Clearing the DTC The condition for setting the DTC is no longer present. Reference Information Schematic Reference HVAC Schematics (C68) ( See: Heating and Air Conditioning > Electrical > HVAC Schematics (C68))HVAC Schematics (CJ2) ( See: Heating and Air Conditioning > Electrical > HVAC Schematics (CJ2)) Connector End View Reference Component Connector End Views ( See: Vehicle > Connector Views > Connector End Views By Name) Description and Operation Automatic HVAC Description and Operation ( See: Heating and Air Conditioning > Components > HVAC - Automatic) Electrical Information Reference * Circuit Testing ( See: Vehicle > Component Tests and General Diagnostics > Circuit Testing) * Connector Repairs ( See: Vehicle > Component Tests and General Diagnostics > Connector Repairs) * Testing for Intermittent Conditions and Poor Connections ( See: Vehicle > Component Tests and General Diagnostics > Testing for Intermittent Conditions and Poor Connections) * Wiring Repairs ( See: Vehicle > Component Tests and General Diagnostics > Wiring Repairs) Scan Tool Reference Control Module References ( See: Vehicle > Programming and Relearning) for scan tool information Circuit/System Testing 1. Ignition OFF, disconnect the harness connector at the Q46 Air Conditioning Compressor Valve. 2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 2 and ground. ◊If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the FRT HVAC Fuse circuit open, test or replace the Q46 Air Conditioning Compressor Valve. 3. Verify that a test lamp does not illuminate between the B+ circuit terminal 2 and the control circuit terminal 1. ◊If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the K33 HVAC Control Module. 4. Remove the test lamp. 5. Command the A/C compressor ON with a scan tool. Verify the scan tool A/C Compressor Refrigerant Solenoid Valve Command parameter is 100%. ◊If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the K33 HVAC Control Module. 6. If all circuits test normal, test or replace the Q46 Air Conditioning Compressor Valve. Component Testing Static Test 1. Ignition OFF, disconnect the harness connector at the Q46 Air Conditioning Compressor Valve. 2. Test for 7-15 ohm between B+ circuit terminal 2 and control circuit terminal 1. ◊If not within the specified range, replace the Q46 Air Conditioning Compressor Valve. 3. Test for infinite resistance between each terminal and the Q46 Air Conditioning Compressor Valve housing/case. ◊If not the specified value, replace the Q46 Air Conditioning Compressor Valve. Repair Instructions Perform the Diagnostic Repair Verification ( See: A L L Diagnostic Trouble Codes ( DTC ) > Verification Tests > Diagnostic Repair Verification) after completing the diagnostic procedure. * HVAC Component Replacement Reference ( See: Heating and Air Conditioning > Removal and Replacement > HVAC Component Replacement Reference) * Control Module References ( See: Vehicle > Programming and Relearning) for HVAC control module replacement, setup, and programming

Please let me know if that works for you

Thank You

Chad Farhat

ASE Certified Technician

Customer: replied 4 months ago.
What about if i just put a compressor on it
Expert:  Chad Farhat replied 4 months ago.

Check the pressure sensor first ,if okay

than yes replace sensor

Expert:  Chad Farhat replied 4 months ago.

if you clear the codes , does the fault code come right back ?

Customer: replied 4 months ago.
Where is sensor?? I said replace compressor
Customer: replied 4 months ago.
The compressor is running but getting no cold air
Expert:  Mike S. replied 4 months ago.

You have to erase the codes after doing work. Who installed the compressor? Was the system vacuumed down before charging it?

Customer: replied 4 months ago.
I have done nothing...the compressor is running with that code set but does nkt blow cold air at first i figured it was a blend flap not opening but then i scanned it and found this code
Expert:  Mike S. replied 4 months ago.

I thought you said you replaced th compressor.

Customer: replied 4 months ago.
No i asked him if i should just replace the compressor
Expert:  Mike S. replied 4 months ago.

Well, you cannot replace the compressor without having to vacuum down the system afterward, so you are better off just taking this to a shop that does ac work.

Customer: replied 4 months ago.
i am a shop just forget it
Expert:  Mike S. replied 4 months ago.

you should have done what chad said, he opted out