Heater And Defroster Only Work While Driving

[lxrx330ownr]

Hello. I was wondering if anyone can offer advice on a problem that started about two weeks ago. I have a 2004 RX330 with about 117,000 miles on it. I recently noticed that the heater and front defroster do not produce any heat unless the car is actually moving. The fans seems to work correctly at all times, but they blow cold air when I am sitting at a light or idling. The temperature guage also seems to spike into the red while stopped, but as soon as I start moving again it goes right back down into the middle of the guage. It does not appear to be leaking coolant and there are no other lights or indicators displaying messages so I am not sure what the problem could be. I have had the radiator flushed in the past, but it has been a while. Does this sound like something that can be corrected with another flush and/or a new thermostat or am I looking at a new heater core or possibly something worse? I am dreading another trip to the dealership because nothing on this car has even been repaired for less than $1500. Any advice would be greatly appreciated.

[Filehorse]

Based on your symptoms, a roundup of the usual suspects would certainly include the water pump. Also have you checked your coolant level to be sure it's not low? It certainly sounds like a circulation problem and if the coolant level is where it belongs, the water pump would be my next place to look.

[TomC]

Some suggestions:

Is there coolant in the overflow bottle?

When the engine is cold, remove the radiator cap - can you see coolant? If not, the cap is bad or there is a leak in the cooling system. Slow leaks evaporate before hitting the ground, so don't expect to see a puddle. Change the cap (its a maintenance item and use a Lexus replacement part) and have the radiator pressure tested.

Contact Lexus to see if there is a radiator recall.

Good luck.

Tom

[RX in NC]

There was indeed a radiator recall on the 2004 RX330s built in Canada, but not on those built in Japan. If your VIN number begins with J, yours is Japanese. If it begins with 2, yours is Canadian....

But check the usual suspects first including thermostat, radiator cap, and servo motors....

[maglayad]

I have the same problem at 117,000 miles, with a japanese built 2004 RX330. Luckily, no coolant in the oil, no coolant under the oil cap, no coolant in the tranny oil so I hope there is no problem with head gaskets or anything like that. When the heater is on, I get heat when I'm moving, but no heat when I'm idle. I've had to fill the radiator overflow reservoir with coolant a couple of times in the past month. The temp gauge would start to spike high, the radiator fan would also kick in more often. I would pull over and shut off the engine as soon as I see the temp start to spike. I checked the radiator and from the top on both left and right sides and can see signs of orange colored residue running down the sides. Not sure how bad the problem is, but I have an appointment to have it checked out. Any comments? I assume the radiator is shot....