V6 Engine heating up when AC is on then back to normal when the AC is off.

[4runnerV6]

2004 V6 4Runner SR5, 227,000 miles.

My temperature gauge will go to red, while sitting in traffic with the AC on,
once I turn off the AC the temp gauge goes back to normal which is mid level.

Where should I start looking for issues, bad thermostat, bad gauge, blockage with the coolant in the radiator, water pump, etc... any information would be helpful. Thank you.

 

[bamma]

Sounds like a fan clutch or clogged radiator. If your A/C is over pressurized it can put stress on the cooling system too.

 

[4runnerV6]

Thanks

 

[Sungod]

Clutch fan or thermostat. My money is on the clutch fan.

 

[Ralph Blake]

If it gets so hot and over pressured and cap does not release the extra pressure,you could split the radiator at some place and trust me this will be a costly repair or even might be a new radiator.
I would contact a real radiator repair shop not your dealer.