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#4446731 - 07/01/17 02:16 PM What are these AC pressures telling me?
HawkeyeScott Offline


Registered: 01/11/07
Posts: 785
Loc: El Oeste
This is the wife's 2007 Chrysler Pacifica 4.0 with original AC system components. Seemed to cool rather poorly just as the summer began. It blew some cool air but it was definitely under performing. But, just in the last week or so, it seems to have improved on its own. It's not the coldest it's ever been, but it's not bad.

I put gauges on it today. It was 85 degrees out. At idle, the low side read about 19 and the high side ranged from about 240 to 255. Then, at about 2500 rpm, the high side would surge to 325 with the low side pretty much staying put.

Based on what I see online, the low side is a little low at idle and the high side is normal. But at higher RPMs, the low side remains low while the high side is very high. Again, though, the system is putting out a fair amount of cool air.

Blockage? Dying component? Investigate more? Leave it alone? Thanks.



Edited by HawkeyeScott (07/01/17 02:19 PM)

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#4446742 - 07/01/17 02:23 PM Re: What are these AC pressures telling me? [Re: HawkeyeScott]
spasm3 Offline


Registered: 05/30/10
Posts: 8662
Loc: North Carolina
Does the fan work? Condenser clean ? 19 on the low side may be a bit undercharged.


Edited by spasm3 (07/01/17 02:23 PM)
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#4446745 - 07/01/17 02:25 PM Re: What are these AC pressures telling me? [Re: HawkeyeScott]
HawkeyeScott Offline


Registered: 01/11/07
Posts: 785
Loc: El Oeste
Yep, both fans are running and the condenser is clean.

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#4446753 - 07/01/17 02:32 PM Re: What are these AC pressures telling me? [Re: HawkeyeScott]
Chris142 Offline


Registered: 06/05/03
Posts: 16821
Loc: Deplorable in apple valley, ca
Has anyone added refrigerant?
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#4446761 - 07/01/17 02:41 PM Re: What are these AC pressures telling me? [Re: HawkeyeScott]
DNVDMAX Offline


Registered: 11/20/07
Posts: 258
Loc: Richmond, VA
Debris possibly blocking orifice tube or expansion valve.
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#4446762 - 07/01/17 02:42 PM Re: What are these AC pressures telling me? [Re: DNVDMAX]
spasm3 Offline


Registered: 05/30/10
Posts: 8662
Loc: North Carolina
Originally Posted By: DNVDMAX
Debris possibly blocking orifice tube or expansion valve.


Good suggestion, especially if any " stop leak " has been added.
_________________________
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#4446763 - 07/01/17 02:43 PM Re: What are these AC pressures telling me? [Re: Chris142]
CT8 Offline


Registered: 10/09/14
Posts: 10984
Loc: Idaho
Originally Posted By: Chris142
Has anyone added refrigerant?
Chris is a A/C pro !! this.
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#4446766 - 07/01/17 02:45 PM Re: What are these AC pressures telling me? [Re: HawkeyeScott]
mk378 Offline


Registered: 09/27/15
Posts: 1420
Loc: USA
If the suction line from the evaporator to the compressor is not cold, you have a blockage. I think this will be a TXV system and those valves can get stuck. If stop leak has been added of course all bets are off.

If the line is cold, the air inside the car should be cold too, if it is not the heater may be reheating it.


Edited by mk378 (07/01/17 02:46 PM)

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#4446796 - 07/01/17 03:12 PM Re: What are these AC pressures telling me? [Re: HawkeyeScott]
i_hate_autofraud Offline


Registered: 05/19/16
Posts: 705
Loc: Canada

As noted above, put you hand on the exposed pipes near the compressor, the large one ('return' from the evaporator under the dash)
has to be cold.

The small dia pipe off the compressor must be warm/hot.

CHECK your air blend doors & actuators in the dash, they tend to be weak or sticky and won't fully
open to the cold a/c position.

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#4446823 - 07/01/17 03:53 PM Re: What are these AC pressures telling me? [Re: i_hate_autofraud]
mk378 Offline


Registered: 09/27/15
Posts: 1420
Loc: USA
Originally Posted By: i_hate_autofraud


The small dia pipe off the compressor must be warm/hot.


The discharge pipe is normally hot enough to burn you, and it only gets hotter if the refrigerant charge is low, so touching it isn't advisable. It won't tell you much.

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#4446842 - 07/01/17 04:09 PM Re: What are these AC pressures telling me? [Re: HawkeyeScott]
HawkeyeScott Offline


Registered: 01/11/07
Posts: 785
Loc: El Oeste
Initial plan was to add refrigerant but figured that would automatically send the high side pressures higher. Is that an incorrect assumption?

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#4446857 - 07/01/17 04:25 PM Re: What are these AC pressures telling me? [Re: HawkeyeScott]
mk378 Offline


Registered: 09/27/15
Posts: 1420
Loc: USA
The high side being that high, with the fans running and ambient of 85, suggests that there is plenty of refrigerant.

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