Over heating

[Wayne'O']

Hey guys,
I've got an RD28 1999 model GU and only when the air conditioning is turned on the engine temp starts to go up, but if I turn the aircon of the temp goes back to normal. I've changed the thermo fan for the A/C and still does it. I'm hoping someone might have come across this before because I haven't.
Cheers Wayne'O'

[MB]

G’day Wayne ‘O’ mate!
Personally not familiar with the legendary 2.8L but I do find on namesake 4.2 kettles in stock form they really appreciate back to basic clean OEM setups.
A/C fans are a good low speed assistant although the extra load from the A/C pulley engaged does add extra fuel which negates its use. (electrical bypass tips for the fan on only are on here somewhere)
Only nuffy advice I can offer here is to seriously inspect/clean/replace all the originally working good bits.
FWIW: After 17years of service we family replaced our OEM 2001 radiator and did drop some top end 10C heat under full duress :-)


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[jay see]

Is the a/c fan spinning the correct way.

If yes, I'll be checking your cooling system. Process of elimination. Start with the most easiest and cheapest first.

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[the evil twin]

Get the Rad professionally serviced, the symptons you describe are the early signs of old age for a GU cooling system
With the Rad out to get the core rodded the lower portion of the fins can also be cleaned, a quick check of the water pump and thermostat and off you go for another 20 years

[BillsGU]

^^^^^^^^^ What he said! Don't muck about - get a professionalto look at it - it could cost you and engine.

[mudski]

My first place to look would be the radiator and the condenser and see if they are full of dirt/ mud etc. Those symptoms tell me theirs either an air flow issue, or coolant flow. Or both. When you put the a/c on, the condensor will heat up, creating extra radiant heat on the radiator. If there is little air flow, or coolant flow, or both, the radiator cannot get rid of this heat quick enough.

[Wayne'O']

Thanks everyone for your input some great ideas and some where to start, thanks again.