Sanden AC Conversion

tx65coupe said:

I have a 66 underdash AC in my 65. After the new 302 is in, I will be converting the AC to a Sanden compressor with R 134.

I have seen that some of the Mustang parts places sell a complete Sanden swap kit. Well, I don't need a complete kit. The crate motor is coming with a new compressor.

Here are my questions. What all needs to be changed? Is it really just the dryer and the rubber lines/hoses? After that is done do I just evacuate the system and then charge with 134? Do I need to worry about old R 12 in the coils?

Has anyone else done this?

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you need to replace the receiver/dryer to one compatible with R134a. you sould also replace the hoses with barrier style hoses as the R134a molecule is smaller than the R12 molecule. you dont need to change the condenser, as long as it is in good condition, but it is not as efficient as one deisgned for R134a.

as for the rest of the conversion, you need to flush the system of the old oil as completely as possible, trace amounts wont hurt anything. when the system is put back together you need to draw down the system to 30 inches of vacuum, and hold it there for about 20-30 minutes. this does two things;

1: it eliminates all moisture from the system

2: it allows you to check for leaks in the system so you can repair them before you charge the system.

when you charge the system you want to get the pag oil in first, then the refrigerant. when adding refrigerant DO NOT use the old sight glass. with R12 you could add refrigerant until the bubbles were gone and be done. with R134a if you do that you WILL hydro lock the compressor before the bubbles are gone. use a gauge set designed for R134a, they are available at reasonable prices these days. i forget the maximum head pressure you want to shoot for at the standard 70 degree outside temperature, i think it is around 300psi but dont quote me, look it up.

When I did mine, I changed the two hoses from the compressor and the dryer.

I think my charge had one pound of R134.

tx65coupe said:

I like that idea about drawing a vacuum. That sounds like a great idea.

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it is also required as anytime you crack open the system moisture gets in and it needs to be removed otherwise acids can form and damage the system.

Does it make any difference if my car has been sitting in the garage for a few years?

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nope.

Also, I have read about evacuating the system and flushing the system. It appears they are 2 different things. Do I need to do both?

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yes you have to do both unless you are using a refrigerant that uses the same type oil. R12 uses a different oil than R134a or other approved refrigerants, and if the oils mix they will "curdle" and cause problems in the system. evacuating the system only gets all the refrigerant out of the system, where as flushing the system gets all the old oil out of the system. and while changing the compressor and the receiver/dryer does get about 90% of the old oil out of the system, the rest is going to be in the condenser and the evaporator, so they need flushing. there was also be a small amount of old oil in the refrigerant lines as well.

the flush systems all seem to be about the same. as for the hoses from CJ pony parts, they are likely barrier hoses these days since everything is pretty much R134a, or R134a compatible. i think they get their hoses from either vintage air or air vintique, both of whom make vintage looking hoses that are the barrier type. it is the OEM stuff that wont be barrier hose.