2nd Gen Non-Engine/Transmission Where did the A/C Oil Go?

[Matt42]

I am having a terrible time with the A/C in my truck. I discharged it because I had to replace the heater core. Since it's as old as it is, I decided to also replace the evaporator core and the accumulator/dryer. See this thread for the whole story.

http://www.ackits.com/forum/messageview.cfm?catid=2&threadid=9835



I added 6 ounces of PAG oil, as directed by the Dodge TSM, evacuated, and filled with 32 Oz R134a. The system holds 7. 8 ounces of oil, total. It cooled somewhat and acted like I had too much oil in it.



I had discarded the old acucmulator, so I couldn't drain it to see how much oil it had contained. I got less than an ounce out of the old evaporator core.



Today, I took off the *entire* A/C system and drained every hose and part of oil. I got four (4) ounces, mostly from the compressor. About 1/2 ounce came out of the accumulator. I have gotten nothing from the evaporator core, and small amounts spilled from the hoses and aluminum lines that I couldn't measure. I got nothing from the condenser. I've blown out the lines and parts with dry compressed air, with a drop or two more. I've discharged it twice fast, and may have obtained some oil as mist.



Where is the oil? I didn't even get my six ounces back. Do I have to take the compressor apart to fully drain it? All I did was take off the hose fittings and upend it to drain. Has the oil coated the insides of the parts so that it will take some time to drain out? I am leaving the parts to drain overnight, with the fittings closed off with plastic bags and rubber bands.



This is very strange and more than a little annoying! I'll appreciate all suggestions and experience!

 

[Gary - K7GLD]

Doesn't the accumulator contain absorbent filtering material that might retain a fair amount of oil?

 

[JRS]

All of the parts will have a coat of oil in them.



On the partial cooling. Did you measure out how much freon you put back in the truck? I weighed each can, etc. to get what the service manual said the system would hold. Also check for leaks in your gauge (manifold set) I had a brand new manifold set, which come to find out was not assembled correctly at the factory. They had pinched an o-ring, which allowed air to be sucked into the system. the system would only partially cool and my compressor discharge pressure was too high.



Also I painted my AC line that passes by the turbo (the cold one) with some radiant heat barrier paint that they use in NASCAR. And then lightly wrapped it with some of that silver insulation wrap the racers use on hoses and such. It dropped my vent temp. by almost two degrees. I couldn't for the life of me figure out why the Dodge engineers would route an AC line right by a turbo that was dumping out all kinds of heat. (radiant and convective)

 

[Matt42]

Bad Manifold Gauge Set?

Could it be that my Harbor Freight R134a manifold gauge set could be at fault by letting air in? My R12 Robinair set was always very good. Hmm. Ya gets what ya pays for.

 

[JRS]

That's the brand I had trouble with. The high pressure hose connected to the guage set at the factory had a pinched o-ring. Had to replace it. Once I did that, no problems.

 

[wtrenholm]

You don't list what your system pressures have been, hi and lo side. Also what was the cycling rate of the compressor? Time in seconds that the compressor is "on" and then "off". You can also feel the liquid line to try figure if you have a proper pressure drop at the orifice tube, the line should get cold at the o-tube. The evap outlet should be pretty close in temperature and the inlet, maybe a couple degrees warmer. Once it's all back together with the proper oil charge.



Check the orifice tube for debris/plugging as long as you have the system open, if the screen is partially plugged it'll starve the evap and cause poor cooling.



HTH,

Wayne