Power steering does not work at low rpm

The pressure switch is only there to tell the PCM (computer) when the pump is developing high pressure. If the engine RPM is near idle (as when parking), the PCM will increase idle speed through the inlet air control (IAC) valve to prevent stalling. The pressure switch has nothing to do with the function of the power steering itself.

belt worn, loose or idler pulley weak --compressor clutch binding,moisture in system ,compressor internal damage

the engine stalls. (i bet only on a hot engine, , am i right?)
this can be 2 things. but with this huge of engine 1.
the engine idle controls are not idling up.
or extreme, the engine is too weak and the compressor has issues.
does the car driver perfect A/c off? full power and normal hot
engines. and idle speed is at spec hot. near 800 RPM?
(spec, rpm is stated clearly on the hood sticker) open hood look up and under. see that EPA sticker, ?

if RPM is normal. hot.
the engine has huge power.
you turn on A/c and the rpm must not drop
did you try to push the throttle down to prevent the stall.
did that work> yes./no,
if yes,did the A/c belt squeal>?
if that cant work and belt does not scream, the engine has very low power.
the ECU increases idle speed when the A/C is on. this prevents stalls.
this can fail, if the ISC is bad. or diry.

Check your power steering fluid level ?

Hello, This could be an indication your A/C is low on Freon or your Power Steering pump is low on fluid. Both systems are made to increase the idle speed to make the system work better. What happens in the case of the A/C, is the A/C compressor puts a strain on the motor when it engages the electric clutch on the compressor.

The A/C is wired such that when the compressor clutch engages, the engine RPM is increased to maintain the idle speed. The controls do this automatically and when your compressor is low of Freon, there is little resistance and the engine overspeeds. You are burning up your compressor if you lose the lubricant packaged inside it. That noise you hear is a dry compressor.

Turn your A/C or Defroster off and see if the overspeed and the noise stop. The compressor will run in the Defrost cycle too! Eventually your A/C will lose more of the Freon until the low pressure switch cuts the power to the compressor completely.

Some front wheel drive cars have a boost sensor in the power steering assembly for increasing the idle speed when you are turning the steering at low speeds. If the fluid level is low, it tricks the sensor into speeding up the idle to assist steering. Like in the A/C example, you can get overspeed when the fluid levels are low.

I hope my solution is very helpful in fixing your problem. Have your Freon checked or throw in an "OIL Charge" with the proper type of oil for your compressor. Then check your Power steering.

Pump is starting to fail. Good news is that it isn't too hard to change. Hope this helps...

Try turning on the ac or turning the steering. The increased load on the engine should lower the the rpm. If the Idle Air Control valve is working correctly it should sense the load and maintain the rpm or even increase it a bit.. Also this should be cover under warrenty.

If your steering is easier above idle the problem is the pump.

At idle speed the the pressere deliver by your steering pump are low; try to modified your pulley to increase the speed at low idle.