'97_Veronica

I recently purchased my first Vette; she's a 1997 C5, 2LT with the dual HVAC system. The a/c and heat don't hardly work. I read that if the air changes speeds that it won't be an electrical problem, but who knows that could've been written by some hippy who drives foreign cars. I had the blower motor resistor replaced about a week ago but to no avail. I took her in for a second diagnostic test today and the mech claims that I need to have the HVAC control rebuilt. GM had a service bulletin put out saying that the 97-04's need that system rebuilt.The previous owner hadn't done anything about it and now I'm stuck getting it fixed.

I guess I really need to know if that's the real problem or if the dealer is just trying to screw me. I really do need that heater working, I live in Utah and it's already below 30* F in the mornings going to work. I'm open to all suggestions and I'm super desperate.

Also are there any Utah Corvette owners here... and do you have a shop or a "guy" that can help me.

mmartinez

Most problems with hvac head units are resistors that were not soldered correctly, unit has to be removed and resistors re-soldered. I have done this several years ago to my 97. Recently had problems with my hvac not coming on as well, I made a fist and struck the side of the console where the hvac is located, and it came on, not very technical advise, but it came on. Hope this helps.

'97_Veronica

Thanks I'll try anything at this point

BigGun

I've never heard or read anything about a GM service bulletin saying the HVAC unit needs to be rebuilt. I don't think GM will even rebuild them in the first place they just replace expensive parts. That hippy who wrote about the air speed changes was right. If the fan changes speed it is not the blower motor resistor. What do you mean by ac and heat don't hardly work? Use the dic to pull the codes. With key on, just press reset until the screen is blank then press and HOLD options and press fuel 4 times. It will display the codes and go back to manual mode where you can toggle thru the list by using the options button. Just press E\M to exit. Post any hvac codes. I would get it out of that dealership before they rob you blind. It could be the control unit but i seriously doubt it.

'97_Veronica

I pulled the codes last week but the dealer just dismissed them and said they weren't relevant. All of them have the "H" at the end which I believe stands for "history" and none of them have the "C" for "current" but there they are.
Five codes for the HVAC
B0361 H
B0363 H
B0365 H
B0367 H
B0441 H
There are also two codes for the PCM
P0650 H C
P1671 H
Two codes for the BCM
B2721 H
B2723 H
And one code for the SCM
B2177 H

Also last week one of them had both the "H" and the "C" but then I had the blower motor resistor replaced and it seems to have changed so I hope it needed to be fixed.
I'd love to not have to rely on a dealer but I don't know anybody friend or professional that can work on her. I appreciate any and all the help I can get. Thanks

'97_Veronica

I forgot to add that it blows warm-ish air when its on heat and cold-ish air when its on a/c. There's not much difference between those two temperatures though. It almost feels like the doors that swap the air from heat to a/c are stuck open or the actuators/motors (whatever they are) could be broken...? or something.

mmartinez

There is a small hard plastic vacuum line behind the engine's intake manifold, this is the line that supplies vacuum to operate the hvac blend doors, make sure it is not disconnected. Could be a vacuum leak under the dash somewhere as well. Hope this helps.

Bill Curlee

The AIR DAMPERS work off vacuum. Are you able to change the locations where the air comes???????? If the dampers are NOT working properly, the fan air will come out of MULTIPLE locations and you will think that the fan is not blowing the correct volume of air....

The TEMPRATURE is controlled by electric actuator motors that move Temperature BLEND DOORS. The HVAC B Series DTCs all point to issues with BOTH Blend doors. That means you CAN NOT move the blend doors.

You have to resolve that issue!! See if you can hear the blend door motors run when you turn the HVAC system OFF and Back On. They run a recalibration routine each time you turn the system on and off. You should also clear ALL the B series HVAC DTC s and see if the motors try to run and recalibrate. You should be able to hear them by listening closely to the vent areas.

Give that a try.

Bill

'97_Veronica

Thank you Bill. I'll go try it right now. I've tried to clear the codes before but they always resurface in about 5 minutes. Not sure if its supposed to do that or not...

'97_Veronica

Is it closer to the front of the car or closer to where the driver is..

Bill Curlee

If the actuators are working and calibrate,, the DTCs should NOT come back. Sounds line they are NOT working. I had to work mine several times and then they would run and recalibrate.

The vacuum line has NOTHING to do with temperature changes. It just allows the system to change where the air comes out of the vents. Upper vents, Lower vents, both or Defrost.

Bill