MSRMusic

I believe this is the same thing and is certainly easy to check. Disconnect the shorter vacuum hose from the top of the round vacuum valve (yours in the picture has the asterisk * printed on it) and you may leave this unattached. Remove the other longer vacuum hose (yours printed with the O #) from the connection below the electrical switch and attach this hose to the top of the round valve. When your car is running this will pull vacuum on the valve and, if the round valve is functioning properly, will open coolant circulation into your heater core. There are some good pictures posted in the following link:

http://www.clublexus...trol-valve.html .

Hey, Rob. THANKS!! for the details and link to the other pics. I was looking for good pics like these for a while. I'll read over this and try it.

Much appreciated!

Correction: Forget reversing the electrical connection. To test the Water valve VSV, swap the vacuum lines in the module: run the tube going into the top of the round vacuum valve to the electrical swich and vice versa. This should allow constant vacuum on the valve while the car is running and keep the water constantly circulating into the heater core. This would indicate the valve is functioning but the electrical switch in the module is not. It's been a few years since I did this and I just remembered how I tested it.

Hey, Rob321. My sc400 is also having heat problems. Dealer told me it could be a problem with the heater control valve.

My question to you: Is the heater control valve the same thing as the water vacuum solenoid valve?

Here's a picture of mine

http://lh5.ggpht.com/_AcSRZQZTpeU/TPMFRfy4wWI/AAAAAAAAA9w/iaPcFtmUcSE/s800/100_0457.JPG

If this is the part you are talking about, are you saying to take the tube from the top circular area and switch it where?

As much details as possible would be helpful.

and Any help is appreciated.