The never ending wallet suck continues !

[ozkiwi]

When I put the new motor in I installed a new radiator with twin thermos and a shroud.Works great and the fans hardly come on in normal driving but when they do the bring the temp down in short order.
I recently had a new compressor for the air cond fitted because the bearing was getting loud and I was told the thermos have never been connected to come on when the air cond is switched on.The old compressor never blew off gas or got hot but I guess it was not working that well because I drove around
for a year like that.
So now the thermos are connected to the air cond and stay on all the time when its running.
The guy who installed the compressor says my alternator and battery cannot keep up and I need to upgrade both.
Is this normal when you change to electric fans and have air conditioning?
And if so do I need a heavy duty alternator?
Any recommendations?

[Rich84]

Yes. All electric fans are made to turn on when the ac is on. Probably need at least 100 amp alternator if you don't have one.

[mattcrp1]

The fans should come on when the a/c is commanded on especially at low speed driving. This is to help draw enough air over the condensor. Is this a r12 system or r134? Do they even use that down under? Is the condensor set up for your application, such as upgraded to a more effeicient design? Is the system a cycling style or fixed orifice?

[ozkiwi]

the condensor will be the factory fitted item it's a 86 and came with factory air and the compressor is a direct replacement for the factory unit.
Obviously the clutch fan was good enough to do the job and when the thermo fan setup was installed I did not realise they where not hooked up to the air cond switch.It is running the same gas as used in the US whatever that is.
I will get alternator and battery and that should be sorted.

[wilkin250r]

Electric fans draw a LOT of power. I'm not sure what you have, but the singles can draw sometimes as much as 40 amps. With dual fans, each is smaller but can draw as much as 25 amps each, totaling over 50 amps.

And yes, the fans are designed to come on whenever the A/C is on.

The stock alternator is only designed for 65 amps, I believe. That means if your fans are eating 50 amps, you're only giving yourself an additional 15 amps to run everything in your car. That's just no enough, your headlights alone will pull more than that.

Yes, you may need to upgrade your alternator.

Electric fans (in fact ANY electric motor) have what is called an "inrush current", and it means it will usually double, sometimes even triple, the power draw to start them up. They can pull as much as 150 amps to start. You don't need an alternator capable of the full amount, because it's only for a brief second. They'll pull the extra juice from your battery for that brief second. But that's the reason you may possibly need to upgrade your battery also.

But if you were to ask my personal opinion, I would say you DO need to upgrade your alternator, but you don't need to upgrade your battery, as long as your current battery is in good condition.

[mrolds88]

On cars I have worked on with factory electric fans, only one of them comes on when the A/C is turned on. Upgrading to a bigger alternator and battery isn't a bad idea either. Last two diesel pickups I've had I replaced the batteries with 900 CCA units (2 per truck). Never had a problem. Better to have "too much" instead of it leaving you wanting.

[ozkiwi]

I think the battery is needed as well it's 8 years old.

What are the ULTIMA agm's like ? It's the only ones available here that has the 4 terminal set up curently in the truck or should I be looking at putting heavier battery leads in as well?

[cadillac_al]

I'm with mrolds, I would set it up so only one fan comes on with the AC.

[wilkin250r]

Having only one fan come on with the A/C is certainly a possibility, and if you did that you may indeed be able to avoid upgrading the alternator.

But alternator upgrades are generally pretty easy. They can be found easily for less than $75 and is usually something even a novice mechanic can change.

Electrical modifications may be more difficult unless you are electrically inclined. And I hope I don't offend the original poster, but if he has to ask about the validity of alternator upgrades, it tells me he doesn't understand the basics of current draw and electrical loads, so he may need a mechanic to make the necessary changes.

If it came to a choice of upgrading the alternator himself, or hiring a mechanic to change the wiring for the fans, then the alternator is easily the cheaper option.

[ozkiwi]

Originally Posted by wilkin250r

Having only one fan come on with the A/C is certainly a possibility, and if you did that you may indeed be able to avoid upgrading the alternator.

But alternator upgrades are generally pretty easy. They can be found easily for less than $75 and is usually something even a novice mechanic can change.

Electrical modifications may be more difficult unless you are electrically inclined. And I hope I don't offend the original poster, but if he has to ask about the validity of alternator upgrades, it tells me he doesn't understand the basics of current draw and electrical loads, so he may need a mechanic to make the necessary changes.

If it came to a choice of upgrading the alternator himself, or hiring a mechanic to change the wiring for the fans, then the alternator is easily the cheaper option.

No offence taken that's why I come to this great site! I am greatfull for your knowledge sharing and I am ignorant of all things electrical in relation to current and electrical load but shouldn't be so lazy and just have done a bit of research.(Too easy to ask here) mechanical ability is fine so fitting the alternator is no problem.I have decided to get a 140 amp alternator and a new battery and be done with it.