vt overheating only when air conditioning is on

[somedude_855]

hi dudes as it says in my title my car runs fine but once i turn the air con on the temp starts rising and the temp light comes on and once i turn the air con off it goes down again. I checked my thermo fans and they are functioning properly. so now i am confused does anyone have any ideas?? thanks heaps

[VR38]

A few things to check, is the thermo fan working? Is it spinning the correct way? Is it upto speed or a bit slow?

Is the condenser dirty?

Is the radiator core worn or partially blocked?

[Leo.Bullterrier]

We had the same problem in our 1975 Toyota Crown and it has a twin aircond system, the problem was the core was blocked so while we were at it replaced the radiator and the coolers and never had a problem again.
We are thinking of putting a Commodore V6 in it to make her more highway friendly when towing the camper when retirement comes.

[somedude_855]

thermo fans in my opinion are working as they should, radiator is nearly new. shouldnt there be another fan in front of the ac radiator. my old vh had one

[BlackVXGTS]

Your fan should energise at low speed as soon as you turn on the air conditioning - check this. Your fan should then turn on to high speed as soon as (amongst other thinks) the coolant temperature becomes excessive and before the warning tone sounds. Check that your high speed fan relay is working properly - pull it out and replace a couple of times and try swapping with a similar type/capacity relay.