Air Conditioning

[lhoudyshell]

Car is 1979 911 SC, with add on A/C years ago. Recently converted to R134A coolant. Have noted that when AC not on volt meter shows 13-14 volts. When AC on volt meter only shows 11-12 volts. Any ideas what may be going on here? Is there a potential problem? Lynn

[Bob Kontak]

Voltage across battery terminals, corret?

Voltage regulator may be bad. Voltage readings should vary in the hundredths of volts not tenths or half volts. This assumes you have that big of a range.

As to dropping below 12 volts, I am not sure - not an auto electrician. Seems that voltage should not drop below 12V, ever, with a functioning alternator.

[86 911 Targa]

Originally Posted by Bob Kontak

Voltage across battery terminals, corret?

Voltage regulator may be bad. Voltage readings should vary in the hundredths of volts not tenths or half volts. This assumes you have that big of a range.

As to dropping below 12 volts, I am not sure - not an auto electrician. Seems that voltage should not drop below 12V, ever, with a functioning alternator.

I agree, the voltage on our '86 holds steady @ 13.5 volts when several accessories including the A/C are active.

And +1 on the VR.

Gerry

[Mitch Leland]

Originally Posted by lhoudyshell

Car is 1979 911 SC, with add on A/C years ago. Recently converted to R134A coolant. Have noted that when AC not on volt meter shows 13-14 volts. When AC on volt meter only shows 11-12 volts. Any ideas what may be going on here? Is there a potential problem? Lynn

Just to be sure what's going on have you checked to see if you have a voltage drop when you turn on the head lights, or the heater blower... By doing this you might determine if it's in the charging system or it's in the A/C system.

[lhoudyshell]

All good ideas, will work at this problem. Thanks for the thoughtful responses. Lynn