tickman

Hey there guys 1st time post. I googled this and searched with no luck.
I pulled into work 2 days ago and my car started to over heat just enough to loose water but did not go into the red. I added some water after it cooled down and noticed it over heats with the ac on and goes back to normal when I cut it off. It takes it a while for it to over heat. The fan is hydrolic with the power steering pump and does not change speeds when I cut it on so I leaning toward draining it and putting more atf in since the oil is dirty. Any ideas? I seen something about a valve on the power steering pump but nothing about testing it or if I can take it off and clean it or what it looks like. And is that the filter on top of the radiator. Sorry for long post, I been googling all night.
1996 300es

immax01

It overheats enough to lose water? Where are you losing water from? Are you losing coolant?

When the engine is cold, open the radiator cap, is the coolant to the top? If not. Top it off and watch for leaks.

Welcome to CL!

tickman

I lost some coolant from the reserve and replace the radiator cap and refilled coolant. the radiator was alittle low and put rest in reserve. No leaks, runs fine without ac on.
I pritty sure its a hydraulic issue because it acts up only when turning on ac and fan stays at one speed with and without ac on. It really hasn't been real hot outside either.
A/C cycling switch or power steering solenoid is what I'm looking at but dont no how to test either one or maybe a fluid filter flush. I believe the ac switch controls the solinoid to open for more hydrolic fluid to run to the fan and incress fan speed. Is that right.

tickman

Going to try flushing first, does anyone know how to test the siloniod and switch

CUMan

There are numerous threads about overheating problems associated with the hydraulic cooling fans used in the 1992-1995 ES models. The usual culprit is a connector that somehow gets removed from its proper position on the power steering pump.

This is one thread:

https://www.clublexus.com/forums/es3...g-problem.html

GEORGE_JET

Try the test fan test that is refered to in the previous post. This will tell you if everything in the fan circuit is working properly EXCEPT the coolant temp sensor. One very improtant point to realize is that the engine has several coolant temp sensors. One sensor is obvious, the temp gauge in you dash. The ECM uses another sensor (why they do not share the same sensor is beyond me, but they do not). And I believe that the fan controller also uses a separate one.

Anyways, run the test with the jumper wire to check the circuit. If that responds as it should. The next step is to test the temp sensor itself. With these two test, you can tell if the entire system is working properly.

Ps, the fan does not kick in to a higher speed when you are idling, and turn on the AC, I have tried this on my car and can confirm this. I am confident that my system is working fine, it has been over 100 in TX for the last three months, my car has not gone over half way mark on the gauge.