dlap

Hey guys. Today i turned on the heat in my '05 430. I noticed that when i stopped at red lights, the heat turned cold. And i mean A/C cold. As long as i have the gas peddle pressed, it warms up. Never really getting hot after 20 min of driving. The A/C button is off. What is causing the heater to blow cold air. And i mean cold air when the car stops. Thanks for your help. 164,000+ miles.

Lynzoid

Check for coolant leak. Asap.

Jabberwock

Could be any number of things - something like stuck or broken HVAC vent doors. Plugged up heater coil inside the car. Or less likely but could be a stuck open radiator thermostat although I think you would still get some heat. It could be something fairly simple or something more serious. I am assuming the temp gauge on the motor is reading in the normal range. Get it looked at sooner rather than later.

dlap

Yes temp gauge is normal. Its 5:30 am and 52 degrees. When i got home i heard the fans come on. Just a 10 min drive to my destination.

Lynzoid

Did you check coolant level? I had SAME symptoms just to realise 20miles down the road that my radiator is blown and leaking all over the place.
Temp gage did not and will not move in case of coolant loss. Temp sensor is designed to measure coolant temp, not air temp when all coolant is gone.

yuri.ber

iTrader: (7)

I have the same thing now. Check your coolant level. In my case my top radiator seam is seeping antifreeze. I filled some coolant and all is good but will need to replace my radiator soon. Too bad shop I usually visit was flooded by Sandy

Lynzoid

Hang in there, bratishka!
Just for info, had to pay 300usd for radiator repair (lower plastic tank cracked but to freezing temps -30c/bad coolant), cos my type of rad (with expansion tank) is rare and expensive (500+). Yes, there's two types of rads in LS430 - one with expansion tank (expensive and toyota only part) and one without (oem replacements available).

dlap

Coolant level was low. Filled to full. Started and drove around the corner. Heater still blowing cold. Call a lexus repair shop and guy said that it could be an air pocket in their since coolant was low. Said to drive and check coolant to see if its leaking out. Im not gon drive too far.

yuri.ber

iTrader: (7)

Spasibo! I already looked and saw that there are two radiators: 5023 and 5024 with a towing package.
So I just need a regular 5023 part? Is a 5024 part better in any way and should I splurge on it?
Thanks.

Lynzoid

Two completely different cooling systems. You cannot interchange.

dlap, find an incline and drive on it. hold on parking brake and slightly rev engine for 5mins while heater set to HOT/MAX. Then recheck.

Reason for coolant loss still unknown?

yuri.ber

iTrader: (7)

Top radiator seam has a small leak. Oh well this will have to wait for a month or so since finances are going to get back on our feet due to Hurricane Sandy.

dlap

Topped it off for the third time. This time heater blowing hot. Will check in the morning again. Thanks for the help so far. I did t see any coolant on the ground or anything. Did the coolant just dissipate over the years. Bought the car in '08 and i have never added coolant. (A mistake i will never make again). Is this the reason why it was low?

Lynzoid

Highly unlikely. Pop your hood and use a powerful flashlight to inspect the rad's surroundings...
My bet is on leaking rad, sorry.

Jabberwock

If you can't see the leak you can take it to a shop that can do pressure testing and ask them to pressure test the cooling system. They put a special pressure gauge where the radiator cap normally goes and run the engine for a few minutes - if it does not hold pressure then there is a leak somewhere. If there is a leak but its not easily visible - next thing the shop will do is use some special dye that fluoresces in the coolant and then use a light to check for leaks which will show up with the dye.

john339

All good suggestions and here's mine.
It could be the radiator cap. The pressure test will tell.