'98 Dual HVAC Controls

DRR · 10-17-2007, 03:15 PM

I have a '98 Vert with dual auto control hvac. At the end of summer I started to get warmer air (+15 deg. ~) out of the driver side vents (even on recirc.) though the d/s temp control knob was set to full cold, and the pass. side vents blew nice and cold. Is this a control board issue? I'm hoping someone has repaired this problem already and can save me some time searching in my service manuals. Any advice?

Doug

RichieRichZ06 · 10-17-2007, 04:23 PM

Quote:

Originally Posted by DRR

I have a '98 Vert with dual auto control hvac. At the end of summer I started to get warmer air (+15 deg. ~) out of the driver side vents (even on recirc.) though the d/s temp control knob was set to full cold, and the pass. side vents blew nice and cold. Is this a control board issue? I'm hoping someone has repaired this problem already and can save me some time searching in my service manuals. Any advice?

Doug

Many have stated that disconnecting the battery and then touching the two cables together for a few seconds (while disconnected of course) is enough to reset the system and make it work fine. If not, then it is most likely an issue with the blend door on the drivers side. It may not be opening and/or closing all the way and letting some extra air blow through that is the wrong temp. The control heads in those are suprisingly reliable, compared to the actual temp actuators on the heater case.

stevezfl · 10-17-2007, 06:16 PM

Doug,
We have the same year car and mine did the same thing.

Check your system for codes. If it's the same problem I had, you will probably find two codes, referring to the HVAC system and actuators out of position.
This happened to me by simply disconnecting the battery to clean.
In manual mode, Toggle through the codes and when you get to the HVAC ones, clear them.
I'm sure you will hear the flaps under the dash move and reset.

Hope this works.

Scubanme · 10-18-2007, 01:13 AM

Make sure that the vacumm tube (small 1/8" dia. hard black plastic tube) in back of the intake manifold is not cracked or fell off. it is located near the MAP sensor and goes down behind the battery leading
down to a vacumm thingy near the PCM on the bottom of the right front fender. The plastic tube is connected to the intake with a 90 deg.
rubber boot.

DRR · 10-18-2007, 09:06 AM

Thanks Rich, Steve and Carl. I will dig into this on my next days off and post my results.

Thanks again,
Doug

DRR · 10-29-2007, 03:18 PM

Thanks again to all for the help. I get no codes. I tried a couple of different resequence proceedures, (shorting the positive battery cable to ground, as well as pulling fuse #27 in pass. footwell) the actuators resequenced, but I still get warmer air on the drivers side. I now suspect that the gear on the left actuator motor is broken. I am looking for a way to confirm this before I replace it, as it sounds like major dash surgery.