my car stalls when the AC is on in the car,why is that?

Question

When driving then slowing down with the AC or that windshield defogger on my fordwindstar stalls. What could be wrong with the car. Car is fine if no AC is used ,no problem using heat also what up with that?

Answer 1

You idle is off. In most newer (post 1996 and sometime even as old as 1994), car had electronic controlled idle (IAC - idle air control).

The IAC is supposed to bring the idle speed up a little when there a load at idle so the engine does not die. Your IAC module is probably bad or going bad.

Some older cars with IAC (and carburetor engine) had screws that you can turn to up the idle. With these cars you can pre-compensate and turn up the idle but then you would be using more gas when just idling. Once you get moving it would not make any difference at all.
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Besides the blower motor, AC is not fed off the battery or the alternator. But they eventually all load the engine and drops the engine idle RPM speed. If you want to make sure, try connecting a jumper cable and have both car running. If your alternator is not supplying enough juice, then the second car will. Now turn on the AC. If the car still runs fine, then it would be the alternator. But I seriously doubt your alternator is the problem.


Good Luck.

Answer 2

There are some cars which are proned to this problem, without mentioning the makes, one thing which is not obvious to everuone is that the AC unit has a "Drip" pan for the overflow. If this is full, the AC unit becomes slow and eventually "clogged", as a result, the electrical operating unit "dies" until the car is re-started after a little rest. Sometimes it won't start first thing in mornings because of this also. If you have found this,and,,,had to push the car, just a few feet, and then it's ok, get a garage to check this "overflow" pan.It may solve your prob's. Hope this helps.

Answer 3

A few that would be helpful, the year of the van, the motor size, and how many miles are on the van. this problem is one thoughts things that can sometimes be difficult to pin down. if your not getting a check engine light, then I would look at worn parts. When was the last time you had the plugs and wires replaced on the motor? Do you have normal oil changes? (Every 3000 miles?) is this a recent problem or have you noticed it over the course of time? Other then the AC have you noticed any other performance problems with the van? Poor fuel economy? Not pulling a hill like it used too? What I am getting at is it's likely it's getting time for a complete tune up on this van. This entails replacement of the plugs, wires, fuel filter, air filter, oil and oil filter, PCV valves, and if after inspection, replacement of some vacuum hoses. I'm pretty sure that after these are replaced the problem will be resolved.

Answer 4

I have subaru and in az it gets hot. When the ac is running the car stalls. Pls I need help.

Answer 5

It's NOT battery related.....

The A/C pump uses some of the engine horse power to turn it. When you turn it on, the engine idle speed needs to be increased a little to make up for the horse power draw.

Something in the idle circuit is not working right.

Take it to a pro before you just start replacing random parts.

Answer 6

Your alternator is going bad or your idle speed needs to be corrected. Don't wait!

Answer 7

it sounds like the idle kick up isn't working.
when the a/c or defroster is turned on, the engine will bog down because of the extra load.
so when that happens, there's a solenoid that kicks the idle back up to compensate. sounds like that solenoid isn't doing its job, OR your idle is out of adjustment anyway.

Answer 8

sounds like an electrical problem. check connections first. (at the battery etc...) then have you alternator and battery checked.