Mechanics

FORD FOCUS ENGINE PROBLEM

2003 Ford Focus • 65,000 miles

When you turn on the heater it engages and dis-engages the air conditioner compressor in other words it clicks on and off and when it engages it makes the motor cut out bad and even when you turn on the air conditioner it makes the motor cut out turn the heater off and it is fine or the air
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Guest
January 26, 2013.



The AC compressor is supposed to run in the defrost mode to dry the humidity from the air before it gets blown onto the cold windshield where it would otherwise condense and cause fogging.

Caradiodoc
Jan 26, 2013.
So what are you saying that is not answering my question what is the reason behind this what is causing the problem

Tiny
Randy sharp
Jan 26, 2013.
It's hard to know what you're saying when you don't put punctuation in your really long sentences. The AC compressor running on defrost is normal. Cycling on and off is normal too unless it's occurring very rapidly. That can be due to the cold weather or the system could be low on charge. If it is low on charge, let it go for now. It's hard to service AC systems when it's below about 70 degrees. If the cycling goes back to normal when it gets warmer, you likely don't have a problem with the AC system.

If the idle speed bogs down when the compressor kicks in, that is due to a problem with the idle speed control valve. Ford has always had a lot of trouble with their design, but very often you can remove them and clean the passage. Carbon buildup blocks the air flow around the throttle blade.

If you feel any rough running when the engine bogs down, that is due to a misfire. Beginning with '96 models, the Engine Computers will detect them and set appropriate diagnostic fault codes, but sometimes they're masked, or appear to smooth out at higher speeds. You really shouldn't be having a problem yet at the mileage you listed but if you do feel rough running, start with tune-up items like spark plugs, spark plug wires, or ignition coils, depending on which engine you have. The idle speed control valve is supposed to have enough control to overcome a speed issue related to a misfire but sometimes it takes a while to respond.

Your mechanic can use a scanner to command the idle speed control valve to various settings to see if it's working properly. If the solenoid is gummed up or full of carbon deposits, that will be aggravated too by cold weather. The Engine Computer may be commanding it to open more, but if it's sluggish, it may not respond. The AC compressor puts quite a load on the engine, especially to get it started, so I suspect you have an idle speed problem, not an AC problem. Also, since the compressor is run by the Engine Computer, it knows when it's about to cycle it on, and normally it will bump up the idle speed just BEFORE it energizes the relay.

If my guess is right, the engine should run fine if you hold the gas pedal down just a little. Once you do that, the idle speed control valve goes out of the picture. The engine speed still might change when the compressor kicks in but that can be expected because what you're doing isn't exactly a normal condition that the engineers designed for. Pressing the gas pedal is normally accompanied by road speed, not standing still.

If the engine still bogs down when you're pressing the gas pedal, one test is to unplug the compressor clutch, then see if the idle speed changes when the computer turns the relay on. Typically it will bounce up, then come back down within a few seconds. If that does occur, the computer has control of the idle valve, and the valve is working. That would point to a compressor problem, and that would be rather rare. Compressors can lock up from something broken internally or from an over-charge, but it's not common for them to just turn hard.

Caradiodoc
Jan 26, 2013.
Ok what about when you turn on the heater it causes the compressor to engage and as long as you have the heater on the compressor will just kick in and kick off clicking sound and also it will make the motor cut out bad turn the heater off and the motor runs great. When you turn the ac on the compressor kicks in like it suppose to but it does not click on and off it stays engaged but to it also makes the motor cut out turn it off the motor runs fine the heater is the only one that if you turn it on the compressor clicks in and out. But you what is funny I replaced the belt tensioner pulley the other day and I did not have this problem before does not seem logical that it had something to do with it.

Tiny
Randy sharp
Jan 26, 2013.
To my knowledge the AC compressor should not turn on with the heater except for just the defrost mode. However, Ford does things differently than everyone else, and the Focus is different than most other Ford products. They might have designed it to do something I'm not aware of. Regardless, you're right, logic dictates replacing the tensioner shouldn't be the cause of the problem, but I've been fooled by my logic many times. My best suggestion is to look in that area to see if a vacuum hose became unplugged or loose, a sensor became unplugged, or something like that.

Double-check the belt routing. Even if it's wrong, it's unlikely the AC compressor could be made to run backward, and even if it did, it would still work properly. I can't think of anything that would cause this problem, but sometimes I have to find what I did wrong, THEN figure out why it caused the symptoms it did.

Caradiodoc
Jan 26, 2013.
Well thanks alot for the help

Tiny
Randy sharp
Jan 26, 2013.
Yeah, but did I actually help? Let me know what you find.

Caradiodoc
Jan 27, 2013.