View Full Version : What's up with my HVAC control ???

12-14-05, 06:57 PM
A week ago my HVAC control went blank for what I thought was no apparent reason.
I got back in the car the next day and all was back to normal (the control was on and all functions worked fine). Strange, I thought.
The next day the display was blank again and stayed that way for a week.
No fan or AC was getting old so I pulled out the service manual last Saturday and went through all the wires. I found no problem there and begun a search for a replacement part but as I got in the car this morning (Wednesday) all was back to normal.

Looking back, 2 weeks ago I did have the drivers door wiring disconnected as I was running some new speaker wires (soon before the HVAC control went blank but not the same day).
Could that have caused the problem and it needed to go through several start up's to reset ????

Should I buy a replacement because the thing will fail again when I need AC the most ???

Sorry for the long post but I am confused.

12-15-05, 06:40 PM
The display came back on.
The joy lasted 2 days and it just went out again so I'm guessing something must be overheating on the circuit board causing it to go blank.

Time to get a replacement.

12-15-05, 07:57 PM
I think those are pretty pricey.
Not to mention the way the dash is assembled on Catera, it's kind of hard to get those out of the dash.

If you need some pointers let me know. You'll only need a few tools but you'll need a lot of time and a lot of patience.

I think I have seen that before and a new control head fixed it.
You could go salvage but it might be hard to find the right one in good condition.

12-15-05, 10:48 PM
Thanks for the info.
I found a good used one for $80 shipped so I will be getting that.
As far as taking it out, I have it under control. I'm used to taking cars apart and putting them back together having worked on these Opels in the past.
The 13 phillips head screws are easy to get to and I did have the thing out last Saturday.

I had a close look at the circuits on both boards of the display but couldn't find any defects.
Once I have the new one up and running I might play around with the old one and I'll try to overload it.
That might show where the problem was and what it was. You never know, it might be something simple that goes out on them and I might find a fix.:D

12-16-05, 06:57 AM
I just remember the first time I did one, I was a little grumpy.
I don't like the way they put the switches in the bezel. Of course once you get that out and get the connectors out of it, the rest is easy.

Good luck!

12-16-05, 07:19 PM
Just so you know the thing is working again but for how long ??

I'm not a huge fan of the switches in the bezels either but I keep a bent wire in the car at all times.

When I was setting up my sound system I was pulling them out all the time.

I just wish that what ever is overheating or overloading would blow out for good so I could track it down and hopefully replace it.
I have several old circuit boards that I could use for spares.

06-26-06, 12:57 PM
My AC has decided not to work, everything works, just won't turn the A/C on. Dealer quoted me $1100 to replace, and said it was the Dash Control Unit, which I think was replaced in this thread, so I have two questions.

Where did you get a used one for $80, would love to see if they have any others.

And what are the pointers on removing this thing and replacing??

Thanks you in advance, espicially if it works and saves me $1000!!!!

06-27-06, 07:14 PM
I got the HVAC control on ebay.

Before you go and replace it check the basics first.

Fuses OK ?

Check if your AC clutch is actually getting power to engage.
If not than I would check your refrigerant pressure with the AC off, the suction line should be over 60psi. If it gets too low the low pressure switch will prevent the AC from coming on.

If that all checks out pull the HVAC control out and using a volt meter check if it's putting out the power for the AC clutch.

Or, just get a HVAC control from ebay and throw it in.

06-27-06, 07:24 PM
As for removing the thing, check out this thread.

I know it's how to remove the radio but that's the major part of it.

Once the radio is out that it's just 4 more screws(if I remember right) and the HVAC control and the whole surround will come out.
Pull out the 2 plugs from the control and you have one the battle.

To win the war just put it all back in.