Alternator issues and a/c.
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Driver
Joined: Apr 2006
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From: Texas
Alternator issues and a/c.
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
Lexus Champion
Joined: May 2002
Posts: 2,781
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From: Georgia
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...
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...
Thread Starter
Driver
Joined: Apr 2006
Posts: 121
Likes: 0
From: Texas
Originally Posted by VVT-i
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...
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...
Lexus Champion
Joined: Mar 2004
Posts: 1,973
Likes: 10
From: Arizona
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.
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.
Last edited by Tammy; May 7, 2006 at 11:03 AM.
Lexus Champion
Joined: Mar 2004
Posts: 1,973
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From: Arizona
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.
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.
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