A/C questions

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Jun 12, 2011
So i've begun tearing into the AC on my 94 and had some qeustions. The system sprung a good size leak in the liquid line that runs along the firewall. I will be replacing that along with the expansion valve, drier, and bought a seal kit figuring I would just work my way around the system and do all of the seals I can find.

So, should I oil this thing when I pull the compressor and replace those seals ? Just dump a little oil in the housing ? I know when you charge the system you can add oil but I was afraid of the compressor running in dry mode for that period of time. So should I put oil in the components before I replace them ? Also how much oil should go back in when replacing the parts mentioned above. Thanks in advance for any help, i'm new to air conditioning systems.
The FSM tells you how much oil for each component.

For example, you can dump oil into the drier before re-attaching it. If you've drained a particular item, fill it back up with the proper amount of oil. You really shouldn't try and do it when you recharge as it's near impossible to get the amounts correct.
Hey Half K. doing the same thing plus the compressor...was wondering if you found the proper amount of oil to add? Thanks.
Rule of thumb is 2oz. per component. Cond...2oz. Comp...2oz...Evap...2oz....so on so on. Total of 8oz.
without rear ac 7 oz. with rear ac 8.5oz.
ive recently replaced the condensor and dryer. i asked the aircon man if i should add oil as stated in the fsm. he told me not to bother as it will be drawn out under vacuum and he added more oil for the new components?? i must of asked half a dozen times if he was 100% sure, he said he was. :meh:

the parts cost me over £400 so i want to be 100% sure.
When they vacuum the system out, is that going to draw the oil back out ?

Vacuuming the system will draw only a negligible amount of oil out, if any at all.

If you're unsure about how much is in the system, you can flush the system and drain the oil from the compressor (don't flush the compressor or dryer). Then add in the correct amount of ND8. Since you are replacing the expansion valve, you'll have an opportunity to thoroughly clean the evaporator which can get plugged with debris.
sorry half k, not trying to hijack your thread! we just seem to have the same concerns.

so if the oil just sits in the bottom of the condensor, for example. what use is it serving?
sorry half k, not trying to hijack your thread! we just seem to have the same concerns.

so if the oil just sits in the bottom of the condensor, for example. what use is it serving?

It's only sitting there until the system is charged, then the refrigerant carries the oil throughout the system when it's operating.
thanks coolstream.

so how can the fsm state that each component requires a certain amount of oil when replaced if its simple thrown around the system when charged?

would you say that the aircon man who charged my system is wrong in what he said?

what would you now do in my situation in regards to the amount of oil thats been added/not added to the system?

sorry about all the questions, but no one has ever given me definitive answers on this subject.
The amount of oil a vacuum pump will pull out of the system is minimal. A quality Robinair 6 cfm pump might pull an oz out, but if he's using a R/R/R machine, any oil removed will be captured and he can replace that amount. Using a smaller 2 cfm pump will probably not remove much, if any, oil from the system. The reason the FSM wants you to distribute the oil to the various components is to avoid hydro-locking the compressor. You can get away with having all the oil in the compressor if you turn the front hub of the compressor, a dozen or more turns once it's installed on the vehicle. Did the compressor you bought come with oil already in it, and if so, how much. If it had oil and he added more, it would be easy to end up with too much oil and the system performance will suffer, as the oil will coat the inner surfaces of the condenser and evaporator, lessening their ability to transfer heat.
i replaced the condensor and the dryer.

what would you advise i do now?

trust his judgment?

fingers crossed?

empty the entire system, add oil and pay to have it recharged again?
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