Flushing pag oil from system that has been exposed to atmosphere for months.

Friendly format provided to inquire about automotive a/c systems.
Archived Forum

Moderators: bohica2xo, Tim, JohnHere

Post Reply
benphillips
Posts: 1
Read the full article
Joined: Wed Jul 04, 2018 6:38 am

Flushing pag oil from system that has been exposed to atmosphere for months.

Post by benphillips »

2004 F-150

R134a 33.00 oz PAG 46 9.00 oz

The vehicle was having engine work and the work was put on hold for several months. The ac line was open to the atmosphere the entire time.

Will I have any problem flushing the parallel flow evaporator and condenser?

I plan on removing receiver dryer, expansion valve, orifice tube, and compressor. Then flushing the lines, evaporator, and condenser. Then replacing o-rings and receiver dryer, and Installing a new compressor.

Also, Is it ok to add all 9oz of oil to the compressor?

Thanks for the help
User avatar
bohica2xo
Preferred Member
Posts: 1170
Joined: Wed May 11, 2016 4:12 pm
Location: Las Vegas, NV

Re: Flushing pag oil from system that has been exposed to atmosphere for months.

Post by bohica2xo »

The condenser is a non-repairable filter. Under 100 bucks, just replace it.

You are replacing the accumulator & orifice tube, all good.

Compressors & oil.
So many vendors, and compressors show up with... No Oil / Full of Oil / Wrong Oil / Some Oil

I generally drain a new compressor, then flush it with the oil I plan to use. If you can get all of the oil in the compressor that is ok, but remember to rotate the front hub a few times after install to clear the cylinders. More than likely you can only get a couple of ounces in the compressor, so just put the balance in the accumulator. It is designed to meter oil to the compressor.


Flushing the evaporator
The decision tree for this starts at the old accuulator. Will it come off. Sometimes after 10+ years in place, the accumulator is frozen to the evaporator. Step one is to try removing it. If the entire evaporator needs to be replaced, the time to do this is while the engine is still out of the truck - a fairly easy job.

If the accumulator will come off, then you will be flushing the evaporator. PUT ON YOUR SAFETY GLASSES Once you have removed the old accumulator, clean the threads, grease them up & re-install it. Then grab the rubber tip blow gun & blow in to the evaporator inlet where you have removed the orifice tube. The old accumulator catches the crud from the evaporator. Use some Brake Cleaner spray, and fill the evaporator inlet tube. Hit it again with the rubber tip blow gun until all you hear is air coming out. Remove the old accumulator, and wait about an hour. Go back to the blow gun & blast air through the evaporator - can you smell the solvent? If yes blow for a while, and wait another hour. Repeat until you no longer smell solvent.
Post Reply