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Converting back to R12

Jim1941 on Tue February 10, 2009 11:39 AM User is offline

Year: 1987
Make: Toyota
Model: Pickup
Engine Size: 22r
Refrigerant Type: R134a
Ambient Temp: 50F
Pressure Low: 20
Pressure High: 115
Country of Origin: United States

I have a 1987 Toyota Motor home that I converted to R134a when I bought it three years ago. I want to convert back to R12 for better performance.
My question is can I blow out most of the oil or do I have to super flush everything? When I bought the MH the AC was empty and I fixed all of the leaks and bought a death kit (I was really dumb) I didn't know about this form and did not know any better.
I dumped the compressor when I installed the R134a and added 6 oz of Ester oil. I am sure there is too much oil in the system now. The evaporator and TXV are in a box under the dash and a big pain to remove.
If I have to flush can I use mineral sprits or do I need to buy a commercial flush? Can I flush the receiver and evacuate it or do I have to replace it?
What kind of oil should I put back in the system? My manual says I need between 6.5 and 7.5 oz of oil.

HECAT on Tue February 10, 2009 12:40 PM User is offline

Quote
Originally posted by: Jim1941

My question is can I blow out most of the oil or do I have to super flush everything? When I bought the MH the AC was empty and I fixed all of the leaks and bought a death kit (I was really dumb) I didn't know about this form and did not know any better.

I dumped the compressor when I installed the R134a and added 6 oz of Ester oil. I am sure there is too much oil in the system now. The evaporator and TXV are in a box under the dash and a big pain to remove.

If I have to flush can I use mineral sprits or do I need to buy a commercial flush? Can I flush the receiver and evacuate it or do I have to replace it?

What kind of oil should I put back in the system? My manual says I need between 6.5 and 7.5 oz of oil.

Air will not remove the oils. If the "death kit" contained sealer, you should be ready to flush as soon as you open the system or the sealer may crystallize (if it is such type) in the components when exposed to air. The TXV will have to be removed/replaced to effectively flush the evaporator. Mineral spirits could be used as trace residues would be compatible with the mineral oil needed for use with R-12, you will have to be sure to blow a lot to completely dry it out. A commercial flush would be a better choice as long as it has a suitable formula. You will need to replace the Receiver/Dryer. Go to the A/C flushing page and read the "Flushing Technical Article" to see more about these issues in detail.


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FLUSHING TECHNICAL PAPER vs2.pdf 

Jim1941 on Tue February 10, 2009 1:03 PM User is offline

Thank you HECAT for the quick replay and the good advice. This is pretty much what I though I don't think there was every any sealer in the system.
I will go with a commercial flush and pull the evaporator. I just found a new receiver dryer at NAPA for $21
What oil do you recommend? should I use the r12 mineral or something else?
Thanks
Jim

HECAT on Tue February 10, 2009 1:16 PM User is offline

Use Mineral Oil.

Before you buy anything, I would recommend you take a look here Forum Host for your TXV, Dryer, Oil, & Flush needs.

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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.

FLUSHING TECHNICAL PAPER vs2.pdf 

mk378 on Tue February 10, 2009 1:52 PM User is offline

Did you use the death kit oil can? If you didn't, and just added some ester, ester oil is compatible with R-12. So you don't necessarily have to remove every drop, but you do want to flush to get the excess oil out and start with knowing how much oil you have.

Go over the fan and condenser carefully. A bad fan clutch or a clogged up air side of the condenser or radiator will give poor performance even with R-12. If you're going to use it in extreme climates a fan or condenser upgrade could help.

The evaporator should be fairly easy to remove by taking the glove box out and working through that opening. You don't have to remove the whole dash. Disconnect the lines under the hood and take the evaporator box out as a unit, then open it up to separate the evaporator and TxV.

Edited: Tue February 10, 2009 at 1:58 PM by mk378

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