1990 GTO electrical problem HELP!

Hello all my name is Angus
I have a 1990 GTO

I have been experiencing a weird fault with my Aircon unit.
The original unit screen didn’t work. However, you could still control the AC with the buttons.

I have recently replaced the Aircon screen/ control unit.

Since then whenever I started the engine, the screen would go crazy (as per photos). Recently though, it’s been doing it with just the key in ignition (turned on to “electric mode”) - the only difference being that I’ve disconnected the radio.

I have been told it could be an earthing issue…

Link to video of Aircon unit going crazy:

Some other unusual things:
Battery drains quickly (I have replaced the battery with a new one and everything seems okay so far)
Aircon turns on with ignition

You probably got another faulty climate control.

As for it always starting on ac you possibly have an issue with your ignition on demand (IOD) circuit.

I agree that you most likely have a faulty climate display. Which country are you in?

I will have a look for another then :+1:

Hi Joe, I’m from the UK

I would strongly recommend against buying used displays as they are all around the same age and failing. Overhaul is the best route for a long term solution. A full overhaul is relatively cheap and gives peace of mind.


Are you able to recommend anyone who can do this?

Thank you

I can only recommend myself because I have never used anyone else.


Where abouts are you based and how much do you usually charge?

Yes my unit went faulty and stopped working . i did rebuild with some you tube info works great now

With regards to the battery I have the same issue and I understand there must be a parasitic drain which could be relatively easy to diagnose. I’ve simply installed one of those gadgets on one of the battery terminals that allow you to disconnect one terminal whenever I park the car. Probably a good anti-theft device too. if you wanted to nick a GTO anyway.