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AC Cooling problem in idle


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Fordmondeo
New User

Aug 12, 2012, 12:51 AM

Post #1 of 7 (2861 views)
post icon AC Cooling problem in idle Sign In

Please help..my car AC works perfectly at high rpm but in normal idle 750rpm doesn't blow cool air! I just replaced compressor, condenser, drier and orifice valve but still the same function..anyone has the idea how to troubleshoot this problem? My car is ford mondeo 2007 model.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Aug 12, 2012, 1:56 AM

Post #2 of 7 (2821 views)
Re: AC Cooling problem in idle Sign In

Pressures at what RPMs and temps would help. How was this charged when these items were replaced in detail please. Is this compressor new or rebuilt? Was it spun with oil, oil added properly and important that it be pre charged with refrigerant into a well held vacuum or if available charged by exact weight by equipment that can before allowing engine RPMs on a compressor as oil doesn't move along till the charge is carrying it and can make junk out of a replacement compressor in no time,

T



Fordmondeo
New User

Aug 12, 2012, 2:54 AM

Post #3 of 7 (2813 views)
Re: AC Cooling problem in idle Sign In

Hi Tom please see details below:
1. When engine in idle (750rpm) pressure registered at high pressure line 260psi and at low pressure line 70psi.
That time it blows very little cool air.

2. But by the time you accelerate up to 2500rpm pressure at high line registered 400psi and low pressure line about 30 psi, then very cool air coming!

This really upsetting considering i almost change everything in the system...auxiliary fan is new as well. Im in the middle east and outside temperature now a days range from 45 to 50 degress celcius.
And what more surprises me..by the time i put on AC a sound coming like tik-tik-tik...(this is apart from kicking of pressure disc of the compressor) but when AC off the sounds gone as well..my mechanic says bearing on alternator is the problem..but im not convinced since i remove it and check the bearing by free turning, and in fact how come when AC off there is no sound..if this was caused by alternator it should be there while engine is on.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Aug 12, 2012, 4:30 AM

Post #4 of 7 (2803 views)
Re: AC Cooling problem in idle Sign In

Your pressures are too high IMO and seeing 400 is at cut out point or slightly over. Yes, that is VERY hot weather and really need to know your temp coming into the grille as depending on the surface/area you are testing could be much different in actual air temp. Would be very helpful to have a fast and accurate thermometer.

I like this type not meant for A/C use if pic shows..........



That pic will expire but any with a wire (not wireless) are best and fastest. Household item also available in many auto parts places. Will read either C. or F. temp scales. Put wire end in center vent in cabin and bring the other out in front of grille or vs verse then you can switch to see actual performance quite well. System must have the correct charge. There should be a sticker or decal underhood stating how much.

Depends on your available equipment but can be weighed in with a good scale that can at least measure 1/2 ounce or do the math for grams which is about 14 grams.

Another important read is locked at this section but is this on Charging procedures. Links inside that will not work and I'll see it i can re-do that so they do.

http://autoforums.carjunky.com/..._A/C_SYSTEMS_P45460/

Know that air is a huge enemy of A/C. All efforts to begin charge into a full vacuum that holds and purge lines with just a spit of refrigerant to clear air out of them if they have been open to air at all.

_____________________________________________

This compressor pumping up to 400 PSI is working so hard it is straining and if not shutting down is about to lock compressor on belt or hurt something. Guessing that same belt is running alternator that stress on the belt could be bringing out noise in a bearing like anything but you think alternator. Those bearing need to be perfectly smooth and silent. Sealed little things and if clever you can replace those and not the whole alternator but let's keep that a separate topic.

Condenser must have good airflow and be free of obstructions, dirt, bugs, foliage junk or whatever as well as radiator behind it and things can hide in between them. Poor air flow for any reason would likely spike high side pressures.

Check out that link on charging procedures. It's full of things of what to expect. Could be a lot longer than that and still miss some detail too.

Your call if you see those 400 pressures on what to do next. Vehicle should have a high pressure switch to shut down and or a thermal switch as already said that pressure is too high if accurate,

T



(This post was edited by Tom Greenleaf on Aug 12, 2012, 4:41 AM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 12, 2012, 4:47 AM

Post #5 of 7 (2794 views)
Re: AC Cooling problem in idle Sign In

I see no mention of the condenser fan. Is that blowing strong?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Aug 12, 2012, 4:58 AM

Post #6 of 7 (2790 views)
Re: AC Cooling problem in idle Sign In

Just said air flow not knowing if one or two fans or one or two speeds? That must be correct of course as well as all shrouding. Still contemplating 50C temps should be dang close to 120F in which case you wouldn't find me under a hood at all and who knows what radiant back heat radiator could be messing with the thing from regular radiator?

T



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 12, 2012, 5:10 AM

Post #7 of 7 (2780 views)
Re: AC Cooling problem in idle Sign In

If the fan is working properly and the condenser isn't restricted, it sounds like it's overcharged.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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