skot88

1995 Lexus ES 300

A little background info...
I inherited this car about 4 years ago. At the time the AC had unexpected stopped working, although it would occasionally work. I did not have the money or experience to fix it so we just drove it without AC. At one time I had a “shade tree” mechanic look at it. We add freon and it would cool sometimes , but would also overheat so we just continued to drive it without AC. It drives fine but about 3 years ago the hydraulic cooling fan started revving faster than it should- in sync with acceleration but louder. So loud that I could always tell when my daughter was coming down the street. After much internet research, I have seen all the problems people have with the power steering / hydraulic cooling fan system. Now for my questions. (please keep in my mind I am no professional mechanic, but grew up with a dad who fixed everything himself so I can and have done some auto repairs on my 1992 Paseo (replaced blown head gasket...)
In addition to the high revving hydraulic cooling fan, the power steering pump is now making a whining noise. I think I have spotted a leak in the line from the ps pump to the cooling fan. Now for my questions. Seeing that this power steering system has many interrelated components, I am wondering where, how and in what order to start diagnosing these problems.

Should I start by checking the ECU? If so, how?
Could it be the “air conditioning refrigerant pressure switch” which is the root of all these problems?
Should I replace the power steering pump and solenoid valve? (the wire is connected) or just the solenoid valve?
Should I have the power steering rebuilt (rebuilding it myself is beyond my skills) or buy a remanufactured one?
I know I have to replace at least one hydraulic line. Should I replace all of them?
I am undertaking all of this because I cannot afford to pay someone to fix it. I am confident I can take off and re-install the power steering pump. I appreciate any advice anyone one has. Thanks.
P.S. I have uploaded a diagram of this system based on a hand drawn posted by another member. I hope it will be helpful to others.
Thanks

LeX2K

The first thing you could try is unplugging the connector going to the power steering pump solenoid valve. Do that and report back. Don't drive the car like this, just see if it stops the fan from revving up and down with engine speed.

mtnman82

That drawing looks familiar...

+1 on unplugging the solonoid valve to see if there's a difference, BUT we don't know if the valve defaults to open or closed.

If the fan is going up and down with engine speed, it would seem to me the solonoid valve is stuck open - and when you rev the engine you build up more pressure (which the valve is not controlling) thereby spinning the fan faster. It could also be the fan ecu not working properly.

One other thing is I'm not sure how they sense the fan speed, but if that sensor is bad it could be causing the fan ecu to hold the valve open.

Another thing to try would be actuating the valve manually by applying a voltage to the valve (opposite of disconnecting) to see if it changes states.

Good luck with it!!!

LeX2K

The hydraulic fan itself has no sensor at all on it. I believe the control solenoid is normally closed meaning little to no pressure if not energized, but not certain. But I do remember reading about people that were having over heating problems because their mechanic forgot to reconnect the solenoid after doing some repairs, so it makes sense.

mtnman82

Oh, on your A/C sounds like you have an idea what's going on there - my guess would be low freon (probably a small leak in the system) and the A/C pressure switch isn't letting the system turn on most of the time. You need to check the refrigerent level (there should be a little window for you to see the refrigerent flowing somewhere, or else you'll need gauges). The A/C system is independent of the power steering/hydraulic fan system.

To answer some of your other q's, if there is no power steering fluid leaking I wouldn't touch the pump or lines. If the car turns fine there is no need to rebuild the steering rack. Your pump sounds like it's in good shape if it can turn the fan well enough for you to hear the car coming down the street. If you have to replace one line, I'd do them both at the same time (I'm assuming your talking the high pressure lines which run back by the firewall). My car had 177k+ miles when I did this and I still have the original pump 2 years later (knock on wood).

skot88

Thans for everyone's advice. I drove it a little today after work because it seems like it only starts to over-rev after the engine reaches a certain temp. That was true. This weekend I will do as advised, unhook the wire to the solenoid and see what happens. Just from all I've read on these forums, I believe it is something wrong with the solenoid. I am thinking I can just replace this instead of the whole pump. Of course, since I have one hydraulic line leaking, I will go ahead and replace both of them. I will let you know of my results.

Ab2012

I too am having a similar problem, I recently had a used motor put into my 1992 es300 after a 3.5 year search for a good motor. My fan will not at all "rev" up, thus causing overheating when A/C is on. Could someone high light the place on the pump where the solenoid is located? I have very limited access to the underneath side of my car. Meaning i have no ramps or a jack that i would feel safe enough to lay under, so any help would be appreciated.

CUMan

I Assume that the replacement engine is the iron block engine that was used in pre-94 models. That engine is different from the one that is on my 94 ES, so there may be some differences is the layout of the power steering pump and other engine components.

It would seem to me that you could gain access to the PS pump by jacking up the right front of the car, removing the wheel, and then removing the liner panel. As I recall, the connector for the cooling fan solenoid comes through the firewall and plugs into a connection on the top of the PS pump. The mechanic that installed your new engine might not have been familiar with the solenoid connector and could have failed to plug it in.

Ab2012

Thank you CUMan, ( great name) for the info, I do not believe my mechanic was at all familiar with the lexus, I have found many little details that were overlooked, but I can't complain my car is indeed running under its own power so i can fix the little things. Thanks again for the help

maksud

I am having the same problem. Did you find any solution to it?

My hydraulic cooling fan started revving faster than it should- in sync with acceleration but louder. And it happens when the engine reaches to a certain temperature.

Please reply. I am in a great trouble.