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When A/C on the car bucks a little

WantaSVT said:
Oh OK is it just not enough juice to keep it runnin costantly? And that should knock the problem out
Click to expand...

kinda, the ac system will not run non stop unless the ambient temp is over 90 degrees or something like that. it is normal for the system to cycle. I think it becomes more noticable, and the cycle is quicker when the system is low on refrigerent. also that is just the way it is also ... if there is a leak the system may also be low on oil making the ac clutch harder to engage

please don't just add refrigerent unless you have the proper guages to know what the system is doing ...
 
You may have additional issues. If the system is cycling too frequently then you should get that resolved. BrApple understands AC systems and he has not steered you wrong.

If you indeed have that much idle fluctuation you may also have some engine control problems. You should clean the IAC (idle air control) and clean the throttle body while you are at it. If the idle still hangs up that high you might have a TP (throttle position) sensor problem. If you don't know how to check that you, get a shop involved.

A light surge at about 30 to 40 MPH in 5th gear with the AC on is mostly a normal condition, especially with the SVT. If everything is healthy, the throttle hang fix may help a little as well as confirming that the injectors are clean and the plugs and wires are healthy. This light surge is from the idle air control trying to pick up the engine speed a little and that is why the throttle hang fix sometimes helps. The light surge is aggravated by a light flywheel and the slightly less low end torque from the SVT cams. It is also aggravated by a slightly lean engine and that is why making sure that the injectors are clean.

If the AC has a problem, fix it first.
 
this may help (it was my problem)

this may help (it was my problem)

ive been having an idle problem with my contour 2.0, what can i say its a ford. ive spent 1100 replacing parts, because of enging codes, at first there was none, but after replacing parts , there was always a new one, i now found out that the air intake is plastic, and where the idle air control valve sits,( under the egr valve) the idiots countersink a rounded nut which you would tighten the IAC valve into, they should have put this nut on the back of intake, instead of the front, but instead you bolt the IAC valve into the face of this nut, what happened to mine was stumbling at idle when air conditioning is on, and when in drive, with AC on, I took the bolts out of the iac valve and noticed that one of these countersink nuts were hanging just a little bit out, so i tapped it back in, when i put the thing back in, it ran the same only worse. i took it back out and the one one nut came out, its not back together just yet but i am 100% sure that that is my problem, if ford would have put these nuts on the otherside of the hole, people like us wouldnt have to spend so much money fixing the darn problem, they would have a better name, and japan wouldnt be taking over the market.
if you still dont get what i mean because i have a hard time explaining,
crap= IAC+BOLTS+NUTS+INTAKE ( the way ford built contour)
good =IAC+BOLTS+INTAKE+NUTS ( the way ford sholud build contour)
i will post this add so this idle problem that many have will be fixed, IVE CRACKED THIS NUT!!!!
SCAVENGER!!!
 
I have the exact same bucking when AC is on. First thing I did was got a shop to clean and fill the AC system, and in fact I was quite low. iirc 1.6 of 2.5 (kg?)

But the problem is still with me, even worse actually. I was on a trip recently and I first noticed the problem after really hard driving with the AC on. So I turned it off but I noticed a burning smell. Now the smell comes even under very light driving if I use AC - so I don't use the AC anymore but I need to get this fixed.

Is it possible cleaning the IAC valve could eliminated the bucking caused by the AC? My theory is the constant on/off of the AC was messing up a belt and that was the burning smell. Does that make sense?
 
Tony2005 said:
Yes, or it could be the A/c clutch burning out.
Click to expand...

After taking a look at it and doing a test drive my mechanic said it was the a/c compressor. Which, of course is attached to the clutch... The clutch by itself is a whole lot cheaper (1/3rd the price from my rough searches) so it'd be great if it was just that.

BrApple's statement above got me thinking though ("if there is a leak the system may also be low on oil making the ac clutch harder to engage"), I wonder if the AC has always cycled every 13-15 seconds? And I just never noticed because it was so smooth? If my ac system is low on oil (which I've never personally checked; never knew I had to, or know how to for that matter)

Here are my symptoms:
- Car lurches every 13-15 seconds only if the AC is on.
- Most noticeable around 3.5k rpm. 4.5-5k it's almost impossible to notice and slower than 3k it's harder to tell, although it still happens.
- Just had it serviced a week or two ago, it was low 1.6/2.5, but before it blew cold air and now it blows even colder air.
- Seems like non-ac air is warmer than it was previous to the cycling, I forgot to mention this to the mechanic, but this particular point could be wrong (hotter weather than usual, not used to going without ac in this car, etc).

thanks for any thoughts, sorry to ramble but I don't like leaving out details!
 
I had a surging problem that was caused by low pressure, but there has also been problems noted with the gap between the ac clutch plates getting too large causing it not to engage. I'm just on my way out the door otherwise I'd find the link, but it has been discussed here. Search for a/c clutch problems and you should find it. Tomorrow I'll serach and post the thread.
 
Zetetic said:
After taking a look at it and doing a test drive my mechanic said it was the a/c compressor. Which, of course is attached to the clutch... The clutch by itself is a whole lot cheaper (1/3rd the price from my rough searches) so it'd be great if it was just that.

BrApple's statement above got me thinking though ("if there is a leak the system may also be low on oil making the ac clutch harder to engage"), I wonder if the AC has always cycled every 13-15 seconds? And I just never noticed because it was so smooth? If my ac system is low on oil (which I've never personally checked; never knew I had to, or know how to for that matter)

Here are my symptoms:
- Car lurches every 13-15 seconds only if the AC is on.
- Most noticeable around 3.5k rpm. 4.5-5k it's almost impossible to notice and slower than 3k it's harder to tell, although it still happens.
- Just had it serviced a week or two ago, it was low 1.6/2.5, but before it blew cold air and now it blows even colder air.
- Seems like non-ac air is warmer than it was previous to the cycling, I forgot to mention this to the mechanic, but this particular point could be wrong (hotter weather than usual, not used to going without ac in this car, etc).

thanks for any thoughts, sorry to ramble but I don't like leaving out details!
Click to expand...
Read this thread for info on some a/c issues. a/cswitch clutchgap
http://www.contour.org/ubbthreads/s...er=1301065&page=&view=&sb=5&o=&fpart=all&vc=1
 
Thanks for posting that up Tony, I didn't realise it was so long ago, I thought it was in the new forums. All the info you need should be right there.
 
I have never owned a car that reacted to A/C cycling as much as the SVT. You can really feel the compresson turning on and off. Mine has felt the same from 20k miles to 125k miles - what you are feeling may be normal behavior.
 
I just keep coming back and thinking about this problem. None of the solutions have really resonated with me. Bad compressor? Seems like I wouldn't be getting consistenly cold air. Bad A/C clutch or clutch gap? ditto.

I've spent quite a few hours pouring over ac systems and common problems and by far they're usually related to the heat exchange process not working. But it is working here. Also the vast majority of short-cycling issues are because of low refigerant, and that makes sense. Unless the guy who serviced my system was incompetent I'm not low on R-134A anymore.

So what's the issue? Based on past issues involving corroded wiring - once this shut my car down completely while I was driving down a road, had to be towed; and the much smaller reverse light problem - I think it's the wiring to the A/C pressure sensor. Does this make sense? Seems to me if the pressure sensor wasn't working the compressor would not disengage in the normal cycle of things and refrigerant would just keep on coming full blast, which in turn might either simulate a low-refrigerant condition OR trigger the low-pressure cutoff safety system. But since the refrigerant amount is actually normal either way the system immediately comes back on.

When the A/C pressure sensor gets fixed the flow will be stabilized and so I won't get the disengage/re-engage every 13-15 seconds, but instead at a more normal rate.


I came to this conclusion after reading this:
http://www.focushacks.com/index.php?modid=85
"[Problem:] Compressor short-cycles (on and off very quickly):
* Refrigerant Pressure is too low
-- Check refrigerant pressure, add if needed
* A/C Pressure sensor, or the wiring to it is damaged
-- Visually inspect wiring going to the sensor (it's near the reciever/dryer, a "T" coming off the A/C hard line)
* Expansion valve damaged
-- See a professional mechanic
* Compressor damaged
-- See a professional mechanic"

For anyone curious, here is one of the better a/c system descriptions I found:
http://www.wikihow.com/Fix-Your-Car's-Air-Conditioner
these are also useful:
http://youracauthority.com/acterms/Auto-AC-Compressor-Clutch-Cycling-Switch.shtml (and other links on that site)
http://www.fordscorpio.co.uk/aircon2.htm (actually provides great general ac info along with car-specifics)

I also highly suspect the expansion valve, in fact before I read the first article from above I had the expansion valve as my #1 choice, but due to other wiring problems it didn't make as much sense.

This make sense? Where is the receiver/dryer located in the Contour?
 
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