Question: C5 dual climate control question

[JanS]

When I turn a temperature control knob to heat the AC button light comes on. It blows hot air fine but is it normal for the button to light up? Why no heat button??? Thanks!

 

[JanS]

Re

When I turn a temperature control knob to heat the AC button light comes on. It blows hot air fine but is it normal for the button to light up? Why no heat button??? Thanks!

I can't believe that 48 people have looked at this post and no one can answer this simple question. You all drive the same Vette as me???

 

[gmjunkie]

If you have the HVAC controls set to defrost,The AC runs with it to remove humidity from the passenger compartment.
Try setting your vents to the floor with the temp turned all the way up and see if the AC light go's out,If it don't,pull the codes and lets see whats happening!

Post them ALL , History and Current.

Turn the key to the ON position, but don't start the engine. Clear any present messages by pressing the RESET button. Hold the OPTIONS button down, and press the FUEL button 4 times. This will get you into the CODES section of the DIC. The computer will automatically display all the codes your car has created. It will cycle through each code every 3 seconds. Any code that ends in H is a history code (something that has occurred in the past) but is fine now. Once the computer has finished going through all of it's codes, press RESET to enter Manual Configuration mode. It should start with a module and show "NO CODES" or "# CODES".

 

[JanS]

Re

If you have the HVAC controls set to defrost,The AC runs with it to remove humidity from the passenger compartment.
Try setting your vents to the floor with the temp turned all the way up and see if the AC light go's out,If it don't,pull the codes and lets see whats happening!

Post them ALL , History and Current.

Turn the key to the ON position, but don't start the engine. Clear any present messages by pressing the RESET button. Hold the OPTIONS button down, and press the FUEL button 4 times. This will get you into the CODES section of the DIC. The computer will automatically display all the codes your car has created. It will cycle through each code every 3 seconds. Any code that ends in H is a history code (something that has occurred in the past) but is fine now. Once the computer has finished going through all of it's codes, press RESET to enter Manual Configuration mode. It should start with a module and show "NO CODES" or "# CODES".

It's a convertible and with the heat on and top down maybe that's why it's on? I'll try the heater again when the suns up here. These are the codes

No codes in the following: 10-PCM, 28-TCS, 58-SDM, 60-IPC, 80 Radio, 99-HVAC

1 code in the following: AO-LDCM, A1-RDCM, A6-SCM,

2 codes in the following: BO-RFA

3 codes in the following: 40-BCM

Thanks!

 

[LLC5]

When I turn a temperature control knob to heat the AC button light comes on. It blows hot air fine but is it normal for the button to light up? Why no heat button??? Thanks!

As stated by junkie the a/c will be engaged anytime you have a defrost (front windshield) icon on in your mode display, including the floor/windshield icon. It will also come on at initial start up if you shut the car down and leave the mode selector in the top vent (or face) icon and on 60 in the temp settings, even though you never had the a/c on before you shut the car off. It's infuriating to me, but that is the way GM programmed it.

 

[Otter]

. It's infuriating to me, but that is the way GM programmed it.

2nd that ^

 

[JanS]

Re

2nd that ^

Just figured out that the unit is defective. The mode button does nothing. It stays on floor and dash vents. You can't choose another mode. I'll pull it out and send it off to be re-built. Thanks!

 

[Tuna]

Just figured out that the unit is defective. The mode button does nothing. It stays on floor and dash vents. You can't choose another mode. I'll pull it out and send it off to be re-built. Thanks!

So, your problem is more than first reported after all. Testing the whole system and pulling codes are always the best place to start a trouble shooting session.

 

[JanS]

Re

So, your problem is more than first reported after all. Testing the whole system and pulling codes are always the best place to start a trouble shooting session.

HVAC threw no code, says it's fine but my mode button does nothing. Always shows airflow arrows on the vent and floor. Can't change it to another icon.

 

[dadaroo]

Vacuum is used to control the vents. I would do a vacuum test from the canister to the unit to see if that is your issue. Very common to have an issue from battery acid on the small plastic line. It will not throw any codes.

When Air Comes Out of All AC Vents - A How To Fix Write Up with Pics! - Corvette Forum

Vacuum question - Corvette Forum


Mr. Sam

 

[gmjunkie]

Vacuum is used to control the vents. I would do a vacuum test from the canister to the unit to see if that is your issue. Very common to have an issue from battery acid on the small plastic line. It will not throw any codes.

When Air Comes Out of All AC Vents - A How To Fix Write Up with Pics! - Corvette Forum

Vacuum question - Corvette Forum


Mr. Sam

You are exactly right Sam!

Been there and done that on several older C5's! 03's and 04's not so much,GM had fixed their frigging leaking battery's by then!!~~!

 

[JanS]

Re update

Well it turned out to be the HVAC unit was bad. When I pulled it out of the car the bottom was all sticky from what looked like Coke or Pepsi. I wiped that off and sent it out for repair. The repair guy called to tell me that the drink spilled on the circuit boards and shorted them out. That's why the mode button stopped working. The board was beyond repair so he sold me a good reconditioned unit with a lifetime guarantee. He gave me $50.00 for mine because the power supply was still good and sold me the replacement for $250.00 with my core.

 

[LLC5]

Well it turned out to be the HVAC unit was bad. When I pulled it out of the car the bottom was all sticky from what looked like Coke or Pepsi. I wiped that off and sent it out for repair. The repair guy called to tell me that the drink spilled on the circuit boards and shorted them out. That's why the mode button stopped working. The board was beyond repair so he sold me a good reconditioned unit with a lifetime guarantee. He gave me $50.00 for mine because the power supply was still good and sold me the replacement for $250.00 with my core.

Glad you got it fixed.

 

[Toms007]

So glad that you found the problem. At least you know and have a fix.

 

[froggy47]

When I turn a temperature control knob to heat the AC button light comes on. It blows hot air fine but is it normal for the button to light up? Why no heat button??? Thanks!

Yes it is normal, depending on the MODE you set.

If you do not want a/c set the mode to FLOOR.

 

[JanS]

re

Yes it is normal, depending on the MODE you set.

If you do not want a/c set the mode to FLOOR.

The control unit was bad as discussed before. Replaced it with a re-built unit and it works fine now.

 

[froggy47]

Well it turned out to be the HVAC unit was bad. When I pulled it out of the car the bottom was all sticky from what looked like Coke or Pepsi. I wiped that off and sent it out for repair. The repair guy called to tell me that the drink spilled on the circuit boards and shorted them out. That's why the mode button stopped working. The board was beyond repair so he sold me a good reconditioned unit with a lifetime guarantee. He gave me $50.00 for mine because the power supply was still good and sold me the replacement for $250.00 with my core.

Hmmm,

Well there is no "power supply" on the part you sent him, but still, glad you are up and running.