Hi CL fam
I have a 2005 LS430 with approx 250k she runs really good and I don't plan on getting ride of her. My starter went out last week and the dealer was the only place willing to do the job and provide a car while maintenance was performed. My AC works pretty well accept when i have it on and the car is running yet not moving forward the temperature increases so I have to turn it of before it gets to the top of the heat indicator gauge. I've changed the radiator, the radiator cap and thermostat all with factory parts yet none of that seemed to work. Any thoughts on what it could be before I'm forced to take this in to Lexus and have them properly diagnose it.

 

There is a pair of electric fans behind the radiator. Can you confirm if they come on when you switch on the A/C?

 

Also refrigerant may be low(needs top up) Evaporator fins could be plugged up with dirt.

 

Have you changed engine temperature sensor?

 

Just so I understand your question... You said the A/C works pretty well except when the car is not moving forward, the engine coolant temperature starts to increase which forces you to turn off the A/C, correct?

By design, the radiator is located just behind the front grill and when the vehicle is moving forward, cold air rushes through the radiator to remove heat from the coolant (thus keeping the engine temperature in check). Since the vehicle must be designed for frequent stops, a pair of electric fans are added to move air through the radiator to accomplish the same. The A/C compressor adds a significant load on the engine and so the electric fans are programmed to kick on (at low speed) when the A/C is on with the engine idling. The ECT (Engine Coolant Temperature) sensor monitors the coolant temperature and switched the fans to high speed as required.

This is the reason why I asked you, in my previous post, to confirm if the electric fans are operational.

 

 

If your car ONLY over-heats when stopped but otherwise maintains proper temperature while moving forward, this proves that the water pump is doing its job.

This "over-heat when stopped" is a text-book case of a failing/failed electric fans.

 

Dumb question, but when they pulled the intake to replace the starter, coolant was drained.. Have you checked to ensure the coolant level is correct? There should be coolant visible in the reservoir mounted on the aft side of the radiator.

 

 

 

 

Ehhh, overheated fuel pulsation damper? Could you please make more pictures of your engine? Preferrably, of the following areas:
- thermostat
- engine temperature sensor
- coolant extension reservoir, under air tunnel
- Injectors, Igniters
- Battery connections
- radiator fans assembly from inside
- upper and lower coolant hoses,

 

That white stuff looks like dried coolant residue from a leak. Are your overflow and radiator full? Check the heater hoses above that spot for cracks.

 

Update

I took it to the dealer this morning and they decided to give me a rental so not sure if that means they know something I don't but what ever it is they are covering the bill.