Automotive Air Conditioning Information Forum (Archives)

BluewaterJeff on Mon June 22, 2015 3:14 PM

Year: 2003
Make: Chevy
Model: Silverado 2500HD
Engine Size: 6.0
Refrigerant Type: 134a
Ambient Temp: 90
Pressure Low: 52
Pressure High: 245
Country of Origin: United States

ambient 90 degrees
static pressure 100
low side 52, hi side 245 at idle

Having problem with 70 degree vent temps after replacing condenser, flushed all lines and evaporator w/ Dura II, replaced accumulator, orifice tube.
Compressor is new.
New compressor got 4oz PAG 125 (that's what the old one had in it and Delphi calls for PAG 125), 3 oz went in accumulator w/ a shot of UV dye and 1 oz in condenser.
Charged w/ 1.76 pounds Dupont 134a after vacuuming down to 30mmHG for 1hour.........vacuum held for 15 mins afterwards.

Why are my vent temps so poor, 70 degrees!
Compressor seems a tad bit noisy, not as quiet as the OEM was.
Evap inlet cold, Evap outlet not so cold, cool at best.

Not sure what to do? Was expecting much colder air...........instead its just cool????
Thank you

TRB on Mon June 22, 2015 9:05 PM

Front & Rear listing calls for 2.5lbs.

Front only 1.6lbs.

Might also post pressures at idle and 1500rpm.

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Dougflas on Mon June 22, 2015 9:31 PM

and block off heater hoses to see if the heater is causing a reheat problem.

BluewaterJeff on Mon June 22, 2015 11:21 PM

Thanks
Will post 1500 rpm pressures in am
at idle 52/245
dealership told me 1.76 pounds using my VIN.....thas what I exactly put in. Truck is std cab pickup no rear ac.
will try blocking off heater hose in am

should evap OUTLET be cold? its not
hi side just before the evap is very cold and sweats heavily
evap dripping lot of water

was thinking I might not have gotten all the flush out of evap or too much oil in evap, I used Dura II and vac'd it for an hour. Thought I cleaned it out.
Would the flush boil off under vacuum if I didn't get it all?
thanks

Edited: Mon June 22, 2015 at 11:33 PM by BluewaterJeff

Cussboy on Tue June 23, 2015 1:45 PM

TRB on Wed June 24, 2015 12:07 PM

Inlet and outlet of evap should very cold and similar in temp.

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BluewaterJeff on Wed June 24, 2015 1:20 PM

Ok, I cut off the heater hose coolant supply-made no diff in vent temps still 70 degrees

ambient 90F
static press 100

press at 1500rpm 42/290
press at idle 54/255

inlet to evap is cold and sweating
evap outlet is barely even cool

since only part not new is evap, it appears thats where problem is
What is going on w/ the evap? what do I need to do?
thanks

osalazar on Wed June 24, 2015 1:42 PM

how do I post a question?

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i was driving and my AC blew out hot air after 10 minutes. I got home and hour later it worked fine, no issues since, what the heck happened???

Cussboy on Wed June 24, 2015 2:35 PM

I'm assuming your truck has two electric cooling fans like Mrs. Cusser's 2005 Yukon; are BOTH your fans spinning ?

What happens if you mist some water onto the condenser while running? Do the pressures both drop, and what about the vent temperature?

Edited: Thu June 25, 2015 at 2:06 PM by Cussboy

AC_Doc on Wed June 24, 2015 4:31 PM

A couple of other things to consider.

Next time the air goes warm, pull over and check if the compressor front hub is turning.
Could be the infamous clutch gap thing. If the hub should be turning and isn't, whack the clutch with the end of a hammer handle or broom stick and check for an engagement.
(I know..the compressor is buried under everything. Best done from underneath access).

If you happen to have the warm air blowing at the end of a trip, park the truck on some flat concrete.
Come back in 10-20 minutes and look under the truck cab for water dripping from the evaporator condensation port tube and a large puddle of water on the ground.
It may be that the evaporator is freezing up (solid ice) and no airflow through the core. Given time to melt away, the cold air returns.
This is likely the low side cycle switch mounted on the accumulator (two wires). Check it's operation by noticing if the compressor clutch cycles on-off during normal operation.

AC_Doc

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Sometimes you must accept things at faith value!

AC_Doc on Wed June 24, 2015 4:34 PM

A couple of other things to consider.

Next time the air goes warm, pull over and check if the compressor front hub is turning.
Could be the infamous clutch gap thing. If the hub should be turning and isn't, whack the clutch with the end of a hammer handle or broom stick and check for an engagement.
(I know..the compressor is buried under everything. Best done from underneath access).

If you happen to have the warm air blowing at the end of a trip, park the truck on some flat concrete.
Come back in 10-20 minutes and look under the truck cab for water dripping from the evaporator condensation port tube and a large puddle of water on the ground.
It may be that the evaporator is freezing up (solid ice) and no airflow through the core. Given time to melt away, the cold air returns.
This is likely the low side cycle switch mounted on the accumulator (two wires). Check it's operation by noticing if the compressor clutch cycles on-off during normal operation.

AC_Doc

-------------------------
Sometimes you must accept things at faith value!

BluewaterJeff on Wed June 24, 2015 5:02 PM

Osalazar, you highjacked my thread


Truck is 03 Silverado 2500HD std cab 6.0.........there are no electric fans in this model.
Worked fine til my oem compressor went and I changed everything.
Done this before and no probs ......but this one is a pita.

BluewaterJeff on Wed June 24, 2015 5:05 PM

the compress does not cycle it runs constant........I assumed it was because its so hot here in FL

ascalise on Thu June 25, 2015 1:54 PM

Interested to see what you find. I am on my second 2500hd with similar problems that just started out of the blue two weeks ago.

Cussboy on Thu June 25, 2015 2:07 PM

AC_Doc on Thu June 25, 2015 10:17 PM

BluewaterJeff on Fri June 26, 2015 8:57 AM

yes, my fan clutch is original......I have no cooling issues and actually just flushed the entire cooling system 3 mos ago
coolant runs about 190 no problems.
Might be worth changing out the fan clutch...thanks for the idea!

BluewaterJeff on Fri June 26, 2015 9:38 AM

A thought:
I was talking to tach at Chevy dealership...
He told me "ideal" low side pressure for a 134a system was 35....
He thought that if I went to a diff orifice tube with a smaller outlet I could lower my low side pressures and get better vent temps.
I am currently using ACDelco part # 1533410 (2nd design 17mm at orifice opening...stand tube not a variable rate one)
problem is he could not tell me the orifice size on this tube and without that I have no way to find a "smaller" one??
Does this make sense to anyone...Its a little past my knowledge.
I also red about red and blue Ford tubes??? but know nothing about it.....
Thanks

mk378 on Fri June 26, 2015 10:19 AM

Put water on the condenser see if high side pressure drops a lot and the evaporator inlet and outlet become near the same temperature (cold). If that is the case you need the fan clutch. It takes a lot more air for good A/C performance than it does just to cool the radiator.

Generally when the CCOT's evaporator outlet is warmer than the inlet it's undercharged.