Check steering assist

[courtrin07]

I have a 1999 Lincoln continental, when it gets hot outside and I use my A/C or when it's cold out and I use the heater, I get this message that says "CHECK STEERING ASSIST". It's very difficult to steer, it's like there is no power steering. My car is 4.6L V-8. Hope someone can help me. Thanks in advance.

[geocheb]

I've had a similar problem with my 98 Continental.
My power steering would die and the warning would come up when I drove in the rain, while in slow traffic with my AC on.
Additionaly, the same problem may occur in your car when you have the heat on as the climate control turns your AC on also to regulate temperature, unless you are in vent mode which only warms outside air and turns the fans on.
Check your alternator under LOAD. Start your engine, turn the AC on- max fan, headlights on, and wipers on - the voltage at your battery should measure well above 12 volts - typically around 14+ volts. Your battery voltage with the car off should measure 12.5 volts for a good battery
The power steering is electronically controlled and is sensitive to voltage. If voltage drops under 12 volts it drops the power steering out and gives a check system warning.
After replacing my alternator, I've eliminated this problem.
Another problem that alternator replacement resolved was a lot of battery problems - I had to replace my battery yearly because it was not getting the proper charge under load.