2nd Gen Non-Engine/Transmission A/C recharge question???

[APulpan]

#1 I am finishing up replacing my evaporator core (A VERY BIG JOB) and was wondering if I needed to add any oil if any to the system when I go to recharge it. #2 My dodge book says 2 oz. Also what viscosity oil do I need low, medium, high??? The book does not say that unless ive missed that part. #3 Also I have got some pointers from, a seemed to be pretty knowledgeable guy , from oriellys, he said that I may have to jumper the switch on the accumulater to get the compressor to initially engage so it will start the process, is this correct?? #4 I also was thinking about replacing the orfice screen just for good measure, is that even needed and can I replace just the orfice screen without replacing the Line.

Thanx

 

[mwilson]

You really need to pull a vacuum on that system after having it open. Pulling 30 in. Of vacuum for several hours does two things....boils out any moisture and tests the integrity of the system. Consider doing the work yourself but take it somewhere for the vacuum and charging of the system. You will get better A/C performance as a result. JMHO.

Mike.

 

[B.G. Smith]

If you add oil it must be specific for the refrigerant in the system, I think it is called PAG. If the book says 2 oz. for evaporator replacement then I would add 2 oz. You will have to pour it into a line before you finish the job. The oil specific will be the right viscosity. It might be faster to jumper the pressure switch but not abosulutely necessary as the pressure will rise when you start adding refrigerant. As for the orifice and screen, some are made in the hose, I don't know about yours. If you didn't have a compressor failure the screen may be ok. You probably should replace the accumulator as it is there to catch any moisture that may be left in the systm and as mwilson suggested above, you are wasting your time and money if you don't have the system evacuated before recharge. Hope all works out well. bg

 

[mwilson]

This is on my 2006 and does specify a different oil than PAG if equipped with the 5.9 Cummins. A 2002 may not be like that, see if you have a tag under the hood somewhere.

Mike.

 

[mwilson]

My Thermo King tech drains all of the oil possible from a component into a measure. Then replaces only that much with new oil. I think that is the way to go.

When the system is under vacuum you don't have to jumper anything as the vacuum will draw about 75% of the total charge back in as soon as you open the valve on the refrigerant tank. Compressor will engage at that point.

 

[mwilson]

Was the A/C system empty before you decided to change the evaporator???

Mike.

 

[BDaugherty]

Sanden compressors usually call for PAG 100. I would highly suggest to replace the orifice and dryer since you have it open. On your truck the orifice is made into the liquid line and mot serviceable separately...rock auto has a good price on them. Also, you will need minimum 1 hr vacuum time to remove moisture.

 

[B.G. Smith]

View attachment 88613

This is on my 2006 and does specify a different oil than PAG if equipped with the 5.9 Cummins. A 2002 may not be like that, see if you have a tag under the hood somewhere.

Mike.

Mike, that decal is a little confusing, at least to me. Would the Diesel equipped unit really use a different oil? Or are the different part numbers for the oil indicating a container of oil with the correct amount of oil for the different systems (with enough 134 in it to dispense the oil into the system it)? bg

 

[mwilson]

I think it a result of a different compressor being used with the diesel. I have to stock three different oils at work due to different compressors being used in R134A systems. We use PAG the least. Daimler truck usually specs Sanden compressors so I believe that bdaugherty is correct in his post above.

Mike.

 

[mwilson]

Sanden for rotary and York for piston style is what we see the most of.

 

[B.G. Smith]

Thanks Mike, It's been a while since I changed a compressor, wasn't aware of the differences in oils used> bg

 

[Woodenhead]

I recently changed my compressor and accumulator and resealed the lines I could get to. As mentioned above, to recharge it I took it to a local shop where they added oil, pulled a vacuum for an hour, then charged it. Was about $150 total.

 

[Cosmo]

There are different viscosity PAG oil. Newer stuff typically uses the lighter weight stuff. Alldata says use SP-15 PAG. According to this chart, it's PAG 46.
http://www.johnsens.com/uploads/files/regulatory_lubricantguide4.pdf

I've never heard of a shop putting an A/C system in a vacuum for more than 10-15 minutes, unless they put it in a vacuum then went to lunch. Evac and recharge only pays 1.0 as a warranty time.

 

[mwilson]

We vacuum for at least an hour, longer if the system has been open for any length of time. Any new installs are under vacuum for at least 8 hours or over night. I have seen 10lb systems on a Thermo King be under vacuum for an entire weekend if the system was open to the atmosphere for more than a day. Its all about how well you want the system to perform. No margin for error when protecting perishable products.

I have to run over to the shop today, I'll try to remember to check the oils in stock to find the content. Maybe it is simply the viscosity.

Mike.