View Full Version : EA Air con making engine not start

VT Calais
25-03-03, 09:52 PM
My dad is having a porb with the A/C on his EA Falcon. If the A/C is on and you try to start the engine, either it doesn't start or it cuts out in a couple of seconds. when the car is sitting still and idling without the A/C everything is fine. when you go to switch it on the revs DO NOT change at all. We've checked some vaccuum related hoses etc and they seem fine. Anybody know what could be wrong?

VT Calais
28-03-03, 07:45 PM
surely someone on this site knows of this problem.

28-03-03, 09:58 PM
i dont know the details of how the ford motors control idle speed etc but a friend had similar problems with his ED. can't remember what he ended up doing tho but i think there was a faulty switch or something?

tandy ass
29-03-03, 02:05 AM
Does the air con actually work? IE does it blow cold air when switched on?

When you switch the air con on and off, do you hear a "clunk" noise come from the engine bay? If not, the clutch on the compressor isn't activating.

Stop the engine and try to rotate the FRONT plate on the air con compressor. If you cant turn it then the compressor will have siezed and will require replacement. That'll be why the engine wont start.

VT Calais
29-03-03, 07:38 AM
If the car is already in motion and you switch on the A/C then everything works fine with no struggling from the engine. I don't know about the "clunk" noise - the car is around 1400km away from me.

29-03-03, 11:51 AM
If the cars engine is not running, therefore the alternator isnt on..
and yuor aircon is getting the power out of the battery!
the aircon uses so much power from the battery that it cant start the car..
when your car is on, the aircon is getting power supplied from the alternator

does that make sense?

Start the car b4 u turn the aircon on!

tandy ass
29-03-03, 02:13 PM
Air con clutch uses 3 to 4 amps.

Starter motor uses 150 amps or more.

You do the maths.

VT Calais
29-03-03, 02:24 PM
Bozz; that to me says if the cars starts at all then a measley 3 - 4 Amps aint going to effect it if the AC is on. So I really should be looking at other things apart from electrics.
Please correct me if I'm wrong.

tandy ass
29-03-03, 02:32 PM
I'd be 100% sure its not because of the electrical current flow into the air con compressor's clutch.

Each low beam headlamp uses around 5 amps. Put your headlights on and you have a 15 amp current draw including taillights & parkers. If the engine starts, you can bet your bottom dollar it isn't a weak battery.

I honestly dont have an answer for the problem though since the air con cools the air when the car's started so its not a siezed compressor. Anything else I say would simply be speculation... Certain it isn't a 'feature' of the car? Perhaps someone else has had the same problem and could assist further....

29-03-03, 02:39 PM
when you say 'doesnt start' is that crank-but-no-start, or no-crank-no-start?

this certainly is a wierd one!!

you say it blows cold air, but when you switch it on or off at idle the revs dont change? usually it dips a little then rises to where it was...at least, every EA/D falcon i have come into contact with does that...you sure it is cooling properly?

can you give us any more info?

VT Calais
31-03-03, 07:29 AM
Rollin; sorry, yes it cranks and sometimes starts, but VERY rough and then stops a second or two later. The revs used to change when it was working normally and now they don't. Apart from all this, the AC works perfectly.

31-03-03, 10:33 AM
Was the a/c worked on recently? If so, it may have been over-charged, causing increased load on the engine. Does the compressor cut in and out in quick succession (ie within about 10-20 seconds) once it is running? Otherwise if the gas charge is fine, the step-up regulator (I think that's what it was called) or method by which the revs are raised to compensate for the increased load, may be faulty.

Hope this helps a little?!

VT Calais
31-03-03, 11:29 AM
No, the AC hasn't been worked on for a while.

31-03-03, 12:59 PM
I don't think it has anything to do with the aircond. Has the car recently had a flat battery or the battery disconnected for any reason?

I'm guessing that the computer has just lost it's idle setting for when the aircond is on. My ED has done this a few times after a battery change.

Aircond/off car idles and runs fine. Aircond/on, will stutter and sometimes stall at idle but OK when cruising. Sometimes same stutter and stall when selecting reverse. I probably don't ever start the car with aircond on so maybe it would do as you are saying.

It will relearn the aircond on idle settings in time. There is a precedure to go through to teach it these setting, your Ford dealer would be able to help. It goes something like disconnect battery +10mins, rev at 2000rpm with air-off for so long, repeat with air-on, repeat at idle etc etc or some such.

Good luck!

VT Calais
01-04-03, 08:30 PM
Raptor: No other problems with the car, not for a long time, but I'll get dad totry that reset thingy.


01-04-03, 10:03 PM
i dont know where u guys get the idea that the aircon only uses 3 amps..
when u turn the air con on, dont u guys notice how ur rev's go a bit higher? cos your alternator is making your engine work harder?

headlights10-15 A
parking lights 3-5 A
interior light 1-2 A
radio 1.5 A
air conditioner 15-30 A

tandy ass
02-04-03, 05:32 AM
Originally posted by atomant
i dont know where u guys get the idea that the aircon only uses 3 amps..
when u turn the air con on, dont u guys notice how ur rev's go a bit higher? cos your alternator is making your engine work harder?

headlights10-15 A
parking lights 3-5 A
interior light 1-2 A
radio 1.5 A
air conditioner 15-30 A

i dont know where you get the idea that aircon uses 15-30 amps when in reality it only uses 3-4 amps

Have you read what ANYBODY here has written about how it works? Read the following bold information, its very important-

MOST vehicles fitted with air conditioning have an additional air bypass solenoid that allows more air and fuel into the motor WHEN YOU TURN THE AIR CONDITIONING ON. This is to compensate for the load that the air con compressor puts on the engine.

Go and get an ammeter and measure the current in the wire going to the air con compressor clutch and see for yourself.

Just for your information, if the alternator starts sucking more engine power as a result of a high electrical load, the engine revs will actually go DOWN, not up.

Edit - the blower motor (fan) can use up to 10-15 amps though depending on the car.

02-04-03, 06:03 AM
Had a similar problem in the parents 4x4 ... something dodgy was wrong with the computer, and it wasn't adjusting the revs to cope with the extra load put on the engine by using the air-con. And the same, once it warmed up, and the revs were a little more stable it would work fine. Perhaps you can try a different computer if all else fails? Or check that there isn't a problem with the two "modes" it should have. Not familiar with fords, so can't suggest exactly where to look.

VT Calais
02-04-03, 10:07 PM
Thanks for all the info guys. I've already emailed dad and he is going to try the suggestions you gave on the weekend.

03-04-03, 12:15 AM
I got the current draw list from here


and yea, i notice when i turn my highbeams and soundsystem and stuff on during idle, it revs higher.. due to the fact that the alternator cannot provide enought current so makes hte engine rev more. Like platinum said.

03-04-03, 12:47 AM
Yeah, I think that's right.
I was of the opinion the aircon uses around 12 - 20 amps.

The same way you go to jumpstart another car and the revs drop riiight down as soon as you connect it up and the battery starts drawing current toward it and it's suggested you hold the "doner" car at about 2k revs while the other car cranks over.

Altenators usually only are designed to work at 1/2 their max. rated output rating anyway, which is a but dodgy if you ask me, when they're putting out say 30amps you'd be using say 10 amps of that without the air con on and then things like ABS, power windows, and defoggers use up heaps of power so that all has to be handled... once the drawing current is more than the altenator can handle you run into problems!

But yes, in order to cope with the air-con the load should be evened out with a few more engine revs (and more amps).

tandy ass
03-04-03, 06:18 AM
Just went and measured.

1988 R31 Skyline - 3.1 amps
1993 ED Falcon sedan - 4.3 amps
1998 Subaru Impreza GX - 2.8 amps

So your source is WRONG :p

Nyerr :p :p :p :p :p

In all seriousness, that must be measuring the blower motor as well since that does draw quite a bit of current, I didn't measure any of the cars but since its fitted with a 15a fuse in the R31, I assume thats where it all goes.