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NF Fairlane 302 Voltage Drop with Aircon on 

 

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 Post subject: NF Fairlane 302 Voltage Drop with Aircon on
Posted: Mon Dec 24, 2012 3:52 pm 
Oompa Loompa
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Posts: 36

Joined: 31st Oct 2007

Location: Darwin
NT, Australia

The old girl is giving me a bit of grief again. Have noticed that when the aircon is on the voltage on the dash meter is dropping way down to 11V. Checked the battery with a meter and am getting 12.5v with engine off. Engine on 13.2V. Engine with aircon on at idle 12.5V. Seems a little low to me. Have had trouble for ages with the battery and I put a new one in a couple of months back. It seems to be holding its own, but am worried it may die with this voltage drop issue. Any ideas? I have found an earth from the negative side of the battery that is not going anywhere, it is just wound up and sitting there. It is a Ford lead off the battery lead, but no idea where it should go. If anyone knows where the earth points are from the neg lead please let me know. Only noticed this issue today, doing last minute Christmas Shopping. Got to drive my old mum and dad to Sydney tomorrow for the family get together and dont really want to break down. I will be throwing in a spare battery in the boot just in case! Thanks in advance.
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 Post subject: Re: NF Fairlane 302 Voltage Drop with Aircon on
Posted: Mon Dec 24, 2012 4:34 pm 
EFI Guru
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Age: 52

Posts: 4289

Joined: 5th Nov 2004

Gallery: 28 images

Ride: 351 Vogue,XH 5.0,'17 5.0 Stang

Location: Perth
WA, Australia

I don't know which earth lead you're referring to but you certainly need one going to the engine block. You should measure zero ohms from block to batt negative. This could be the reason your battery is not charging properly.
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 Post subject: Re: NF Fairlane 302 Voltage Drop with Aircon on
Posted: Mon Dec 24, 2012 7:23 pm 
Oompa Loompa
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Posts: 36

Joined: 31st Oct 2007

Location: Darwin
NT, Australia

I had another look at the alternator. Found the big metal strap on the back of it coming from the engine block was not bolted to the alternator. Dont know if it is an earth or for stability but I bolted it up and check my measurements again. I am using a Fluke digital meter that is good quality as well. The V with eng off was 12.6, Engine running 13.6, Engine On and Aircon On 12.6. Gave it a rev with the aircon on and it didnt budge. I have the climate control set to 21 degrees. What should these voltages be? 13.9V? Thanks
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 Post subject: Re: NF Fairlane 302 Voltage Drop with Aircon on
Posted: Mon Dec 24, 2012 7:29 pm 
Getting Side Ways
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Age: 41

Posts: 4629

Joined: 23rd Nov 2006

Gallery: 4 images

Ride: 5.0 AU's and 5.0 Maverick

Power: 139 rwkw

Location: Sydney West
NSW, Australia

They always read low with the AC on on the E series cars.
The thermos are pumping flat out and the internal fan draws a lot as well.
I fitted a BA alternator pulley on our old one after recommendation from a member on here.
It overdrives the alternator a bit and helps.

 

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xr6turnip wrote:
More people paid for a ride in a VT commodore then an AU Falcon so the VT is superior.
Based on that fact my Mum is the best around!

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 Post subject: Re: NF Fairlane 302 Voltage Drop with Aircon on
Posted: Mon Dec 24, 2012 7:57 pm 
Oompa Loompa
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Posts: 36

Joined: 31st Oct 2007

Location: Darwin
NT, Australia

Thanks for that tip. Any idea where I could get one? Is the pulley off the v8 Ba or six, and does it use the same belt or do u need a larger size one?
Sounds like I should be ok for my trip then if this is a common thing. I would just hate to break down with the oldies in the car!
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 Post subject: Re: NF Fairlane 302 Voltage Drop with Aircon on
Posted: Tue Dec 25, 2012 8:57 pm 
Oompa Loompa
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Posts: 36

Joined: 31st Oct 2007

Location: Darwin
NT, Australia

Good news is the car went like a trooper to Sydney and back. Roared along without any hassles at all! Paid particular attention to the volt meter and it sat just off 14V! That big rod really earthed it out good and proper! It has never sat at that close to 14V before. I didnt use the aircon as today was so lousy, but had lights, wipers, and the demister going. Great car, it did really well! Went that well I have her a drink of petrol for about 40kms to keep her sweet! Still want to know about that BA Pulley if you can let me know. Cheers, the pressure is off!
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 Post subject: Re: NF Fairlane 302 Voltage Drop with Aircon on
Posted: Tue Dec 25, 2012 9:18 pm 
Getting Side Ways
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Age: 41

Posts: 4629

Joined: 23rd Nov 2006

Gallery: 4 images

Ride: 5.0 AU's and 5.0 Maverick

Power: 139 rwkw

Location: Sydney West
NSW, Australia

BA 6 cylinder one.
I got mine from the auto electricians for around $40 from memory.
Fits straight up and I just used the standard belt.

 

_________________

xr6turnip wrote:
More people paid for a ride in a VT commodore then an AU Falcon so the VT is superior.
Based on that fact my Mum is the best around!

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 Post subject: Re: NF Fairlane 302 Voltage Drop with Aircon on
Posted: Tue Dec 25, 2012 9:42 pm 
Oompa Loompa
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Posts: 36

Joined: 31st Oct 2007

Location: Darwin
NT, Australia

Thanks for that I will start hunting for one! Cheers
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