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Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Dodge
Satisfied Customers: 1516
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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Ram 2500 truck 5.9 gas: my truck was never equipped from the

Customer Question

my truck was never equipped from the factory with a/c and I am finishing up on the installation of the a/c system. How much compressor oil does the system take? My new denso ac compressor is prefilled with oil but it states in the denso instructions to drain the old compressor and new compressor so I can compare levels. Then fill the new compressor with the same amount of oil that was in the old compressor. I have nothing to relate to since the truck did not have a/c before. are there any technical data sheets?
Submitted: 7 months ago.
Category: Dodge
Expert:  Juan Crespo replied 7 months ago.
Hi there.On this type of application, the amount of oil is determined by the compressor manufacturer; 120 cc or 4 oz in this case.Please let me know if you have any other questions.Best Regards
Customer: replied 7 months ago.

See attached pic....the Denson compressor is labeled 210cc which is a hair over 7 ounces.

Expert:  Juan Crespo replied 7 months ago.
That's a big compressor - not that it's a bad thing, it's just bigger than what I'm used to work with. Use the amount on the label (210cc) so you will comply with its warranty.
Customer: replied 7 months ago.
Relist: Incomplete answer.
Expert:  tims auto repair replied 7 months ago.
Hi, My name is ***** ***** for the delay.I will do my best to assist you.put it doesnt need anymore than 8oz..put the 7 oz in the low side of the compressor and put an oz in the dryer,,it will be fine..the oil will move throughout the system.[note,i normally put 4 oz in the compressor and 4 oz in the dryer]but if the compressor itself soes require the 7oz in the compressor itself put the 7 oz in itthanksIf you are satisfied with my answer, Please Rate my answer by clicking the rating button so I can get credit for my work. I’m not always going to be giving you good news, so please don't let this stand in the way of you accepting my answer. .it does not cost you more money and we will still be able to communicate, ,.please understand, i can not see, hear or touch the vehicle and only know what you tell me. Bonuses and positive feedback are appreciated.. if you are not satisfied with my answer, please do not leave bad feedback ,i will gladly opt out and let another expert handle the question. .if i have sent any diagrams, please print them. .sometimes you may need to right click the image [,then save picture as]to save it to your computer so you can open it with your picture program...Please ask if you need more helpthanks
Customer: replied 7 months ago.

I don't have the Denso instructions in front of me but it states the compressor is prefilled for a full system charge. I'd hate to screw this up and have to buy a new compressor. Should I remove 1 ounce from the compressor and add it to ther dryer so I stay at 210cc or just add 1 ounce to the dryer?

Expert:  tims auto repair replied 7 months ago.
no..if the pump is pefilled,,only put a couple of oz in the dryer..it is fine.
Customer: replied 7 months ago.
Relist: Incomplete answer.
Expert:  Eric replied 7 months ago.
HI, It shows you are requesting a new expert. If you are let me know
Customer: replied 7 months ago.

Yes I am. I am not to sure with the answers I received from the last to experts.......

Expert:  Eric replied 7 months ago.
HI, Ok, because I have had "prefilled" compressors come with as much as 12ounces or as little as 1 ounce, I ALWAYS drain the new compressor of oil into a measuring cup and start from scratch. My years of experience has shown that the manufacturers rarely put the correct amount of oil in prefilled compressors. Once you drain the oil, then refill the compressor with 210cc of oil. Put the caps back on the compressor port and rotate the clutch and pulley by hand about 10 times to ensure it is fully prelubed, then install the compressor. Now add 1 ounce of oil to the drier/receiver.
Customer: replied 7 months ago.

Not sure if this has anything to do with the amount of oil added but it has a hissing sound when the truck is running for alittle bit. You can here it when you are in the cab but when you are under the hood I hear it even more. When I shut the truck off the hissing continues and it gets even louder. It seems the sound is coming from the ac canister/dryer.

Expert:  Juan Crespo replied 7 months ago.
Hi again,The refrigerant will make that hissing sound as it tries to pass through an orifice, such as the expansion tube/valve. This could be caused by the system design (for example: meant for R12 instead of R134a), improper charge, or by a restriction caused by improper expansion tube/valve installation. I could probably tell you more if you would share the brand and part number for the kit you've installed.
Customer: replied 7 months ago.

Most of the parts are OEM. I didnt want to buy a China kit/aut zone garbage and pay more in the long run. Name some parts off and I can confirm if it was oem or for example denso/delphi

Expert:  Juan Crespo replied 7 months ago.
I understand. What are you using to regulate the amount of refrigerant entering the evaporator; orifice tube or expansion valve?
Customer: replied 7 months ago.

Fomg talking to dodge ram owners the orfice tube is in the liquid line so if the orfice tube is bad the liquid line needs to be replaced.

Expert:  Juan Crespo replied 7 months ago.
OK, so that tells me you're using an orifice tube. Now, did you install a new or used liquid line/orifice tube assembly? If used, then yes, the line should be replaced as the orifice tube is probably restricted. However, if the line was new, then the orifice tube might not be the right one for the application and that's why you keeping getting the hissing noise. If that was the case, the repair would be to install a line with a slightly bigger orifice tube. Did you use the evaporator from a truck same as yours?
Customer: replied 7 months ago.

The liquid line is new and I used OEM. It sounds like the sound is coming from the dryer/canister, which is also oem. When I am inside the truck I hear a hissing sound almost like running water where the evaporator is loacted. If I pop my head under the hood I hear it even more. If I shut the truck off the hissing sound gets louder and slowly dies down. Ac drain is draining properly.

Expert:  Juan Crespo replied 7 months ago.
As I previously indicated, the hissing sound is produced by the liquid refrigerant as it goes through the orifice and enters the evaporator. After the refrigerant evaporates, it exits the evaporator as a low pressure vapor, remaining in that state as it enters the accumulator.All these components are engineered to work together; so, if you used OEM parts and those are good, there should not be any kind of abnormal noises or performance issues.I'm a retired Chrysler Master Tech and technician trainer, and as such I'll be happy to answer any questions you have regarding this and other systems in your truck.Best Regards
Expert:  Juan Crespo replied 7 months ago.
As I previously indicated, the hissing sound is produced by the liquid refrigerant as it goes through the orifice and enters the evaporator. After the refrigerant evaporates, it exits the evaporator as a low pressure vapor, remaining in that state as it enters the accumulator.All these components are engineered to work together; so, if you used OEM parts and those are good, there should not be any kind of abnormal noises or performance issues.I'm a retired Chrysler Master Tech and technician trainer, and as such I'll be happy to answer any questions you have regarding this and other systems in your truck.Best Regards
Expert:  Juan Crespo replied 7 months ago.
I just realized the replacement Denso is not the same as the Sanden installed by the OEM. The slight difference in capacities are probably the indirect cause of the hissing sound. However, if you can live with the noise, performance should be the same with the Denso actually having an advantage in durability.Best Regards.
Customer: replied 7 months ago.

I just looked into sanden and they both take the same amount of compressor oil....

Expert:  Juan Crespo replied 7 months ago.
The amount of oil a compressor takes is not the same as its refrigerant- pumping capacity or how it pumps that refrigerant. I'm here to offer my knowledge and experience, not to argue with you. Would you like me to opt out so others may try?
Expert:  Juan Crespo replied 7 months ago.
The amount of oil a compressor takes is not the same as its refrigerant-pumping capacity or how it pumps that refrigerant. I'm here to offer my knowledge and experience, not to argue with you. Would you like me to opt out so others may try?
Customer: replied 7 months ago.

I wasn't trying to argue with you nor put you under that impression. I am on the collision side of the auto industry so that is why I post questions on here since I do not have complete knowledge on the mechanical end.

Expert:  Juan Crespo replied 7 months ago.
That's OK. Not everyone understands the differences between all the available A/C compressors. For your peace of mind, all the information I provide is based on facts. Customers will only get my opinion when it is requested.As I previously stated, I'm a retired Technician Trainer and don't mind sharing whatever knowledge I've acquired during my 40-year plus career. So, please let me know if there is any other information you need.Best Regards.
Expert:  Juan Crespo replied 6 months ago.
Hi again.Just checking to see if the information I provided helped you solve your issue. If it did, then kindly accept and rate my answer now. Please reply if it didn't.Best Regards.