I just bought My 1994 Lexus sc400 about 2 weeks ago.It runs fine but people say that these cars are prone to alternator failure.My question is:Is there a way to see if an alternator is about to go?How do I take it out and what should I look for?I'm also concerned about the A/C.It works really fine now but it's a 12 year old car so I'm sure that there are some leaks there.My question is:What kind of refrigerant do I need r12 or r134a(1994 Lexus sc400).If it's not r134a how do I convert it to 134a.Do I need to buy a whole new airconditioning system?please let me know

 

Welcomes to CL. The 94 SC400 is a great car,but as you'd stated it's a 12 years old car. If your alternator goes bad the first sign you will see is the battery on the dash come on. Make sure you check your power steering for any sign of leak, because the PS pump is mounted on top of the alternator and if the PS pump is leak it will kill the alternator.

Your ac system is R134 the last R12 was early 1993,but you can look on the sticker under the hood.

If it not break don't fix it. Just enjoy and drive it...

 

Thanx for the info.But is there a way I can be able to spot alternater problems before the battery light turns on?I don't want to find out that my alternator is dead when I'm driving 12o'clock at night and get stranded by the side of the road with a dead battery.

 

You'll need a fair quality digital multimeter or volt meter... 15 Volts DC full scale range setting.

This is my procedure for checking the alternator / battery charging system.

Using a digital volt meter, connect across the battery using correct polarity... Doors closed, radio off, all accessories off.... Engine Off ... 11.8 to 13.2 Volts

Start the car, watch the voltage dip down as the starter cranks... as low as 10.0 Volts... As the car starts and idling .. 13.7 to 14.5 Volts

Increase engine speed to 1500-2000 RPM ...Slight increase in voltage then level off....

Back to idle, steady at 13.7 to 14.5 Volts again.... Voltage should be steady and slowly decreasing as the battery is charged.

(You are reading the alternator output supplied to the battery.)

Shutdown the engine ... Battery maintains 11.8 to 13.2 Volts

Disconnect the meter from the battery terminals...
Replace Positive Battery Terminal Protective Cover

Write down the voltage readings and compare over a time for the voltage to drop.

 

As a reference, my four voltages are:

12.491 VDC - Prior to engine start
14.180 VDC - After engine start and idling
14.170 VDC - After engine speed run up and idling
13.180 VDC - After engine shutdown - Static battery voltage

This is on a 575 CCA battery.