Auto A/C high pressure question

[oil&coffee]

Perplexed here..

dodge 2500 2004 diesel.

Charged A/C with approx 2.8 cans (12 ozz).. 30 - 32 ozs..
low side seems good at mid 40's
High side is only at 100 - 110 psi.

Cools great 30 - 45 degrees below out temp. 30ish in drveway / up to 45 on road..

Question is high pressure is only 100 - 110?? Not 200+.. When turn off system the sytem equalizes out..

My thought is maybe the high pressure piston seal is going?? Have 180,000 miles on truck.
Replaced all parts execpt compressor last fall.. Yes I lost the freon somehow over the winter and am now trying to determine if compressor is the one leaking.. NO sniffer here..

 

[cat843]

I would add a leak detector. The proper way is do evacuate the system and hold a vacuum for 30 min. If all is good, then the specified amount (in lbs) is added with oil.

 

[Rock_Hudstone]

Originally Posted By: oil&coffee
Cools great 30 - 45 degrees below out temp. 30ish in drveway / up to 45 on road..

Question is high pressure is only 100 - 110??

Yeah, the pressure sounds low, perhaps it could use a few oz. more refrigerant. On the other hand, its putting out 35-45 degree vent temps, I'd leave it be.

Top off the refrigerant as necessary if you notice diminished cooling.

 

[sasilverbullet]

Originally Posted By: oil&coffee
Perplexed here..

dodge 2500 2004 diesel.

Charged A/C with approx 2.8 cans (12 ozz).. 30 - 32 ozs..
low side seems good at mid 40's
High side is only at 100 - 11o degees..

Cools great 30 - 45 degrees below out temp. 30ish in drveway / up to 45 on road..

Question is high pressure is only 100 - 110?? Not 200+.. When turn off system the sytem equalizes out..

My thought is maybe the high pressure piston seal is going?? Have 180,000 miles on truck.
Replaced all parts execpt compressor last fall.. Yes I lost the freon somehow over the winter and am now trying to determine if compressor is the one leaking.. NO sniffer here..


ROFL!!! This reminds me of the old cartoon of the picture of a Texas pickups dashboard, had a empty can of Dr. Pepper, and a can of freon for the "hot" days!

 

[oil&coffee]

i plan to leave it be until its does stop cooling.. Then do a proper evac/etc.. .. System has a little dye in it.. I am just wondering why it seems to work so well with just 100 - 100 PSI on high side..

 

[Fleetmon]

are you sure the gauge is good? It does sound low on refrigerant though based on your vent temps....I'm surprised the evap isn't freezing on the road. Is the LP switch working or jumpered?

correction - I re-read it and it's 30-40 below ambient temp....great! sure sounds like a bad gauge.

 

[artificialist]

The high side temperature also gets lower based on how much heat the condenser can shed.

Given the size of an engine fan on a CTD, I wonder how mcuh that has to do with it.

Anyway, you should use a service manual to determine the correct high side pressure.

 

[jrustles]

Originally Posted By: oil&coffee
i plan to leave it be until its does stop cooling.. Then do a proper evac/etc.. .. System has a little dye in it.. I am just wondering why it seems to work so well with just 100 - 100 PSI on high side..


If you used one of those "universal" recharge cans with the "green" hydrocarbon aka alkane refrigerants, then you will see better efficiency with less charge, manifesting in lower head temperatures and pressures. Your TX valve is also probably bypassing a little more than you're used to seeing, in turn dropping the high side pressure. Don't sweat it, literally or figuratively.