Aircon taking all the water from my radiator causing it to overheat

[RiffRaffMama]

Heater core. The smell is the heater core.
The mysterious vanishing radiator fluid is likely your intake manifold gasket. For the love of everything that is holy, change those things now. You absolutely will blow your head gasket. If your engine starts to sound like this it's too late.
Could also be something as simple as a leaky radiator cap. Go buy a new one. They're less than $10 from Supercheap. You'd be surprised how much fluid you can lose that way.

 

[RiffRaffMama]

Also, it's Holden Commodore. Please fix your "Member's Ride" info under your name. It's going to really bother me. Thanks.

 

[chrisp]

Also, it's Holden Commodore. Please fix your "Member's Ride" info under your name. It's going to really bother me. Thanks.

The ‘hold-on” bit seems apt.

 

[RiffRaffMama]

The ‘hold-on” bit seems apt.

Depends on what's under your bonnet, I suppose.

 

[Aus78Formula]

I love when people come to ask advice but then want to tell why each response is wrong.

 

[Fu Manchu]

The coolant has loads of reasons to disappear.

The answers have been suggested. Only thing missing is to replace the radiator cap. Coolant could be going out and not back in. It would be overflowing the reservoir.

Heater core is an absolute reason.

When the aircon goes on, additional load can be put on the motor and fans should be coming on. Are the fans on? Maybe the fans not coming on is causing the overheating and a range of other complications like leaking heater core or LIM gasket leaks or a faulty cap are going to come together and bugger your day.

A replacement engine has some alarm bells too. Get the plugs out, what do they look like? Can you get a borescope into the spark plug holes to see what the pistons look like?

Have a compression test done.

Look for dried coolant around the intake base. Around the bottom of the trans where the HVAC drain is and around the coolant over flow reservoir on the right front. Get under there for a look.

Someone has not been doing a great job checking because all these problems would be identified quickly if the correct tests are being done.

Also sitting back and dismissing causes with thoughts will not create a solution. Real solutions are based on physical testing and data, not kind thoughts and magic wands.

 

[RiffRaffMama]

Only thing missing is to replace the radiator cap.

Ahem...

 

[Bay 13]

Bypass the heater core and see if that solves the problem, when you say new motor is it reco or a new secondhand, I thought only one fan comes on with A/C and the other only comes on when temp is over 109 degrees or so.

 

[RiffRaffMama]

I thought only one fan comes on with A/C and the other only comes on when temp is over 109 degrees or so.

I'm pretty sure that's how mine works.