Well I bought a red orifice tube for my r134a conversion in an 85 F150 supercab come to find out that I have an expansion valve. Would it be better to keep the expansion valve or build a housing for the orifice tube that will go where the expansion valve went?

 

Keep the expansion valve.

The expansion valve varies the amount of refrigerant passed through depending on load. The orifice tube is limited to one flow rate.

You did get a good evacuation of the system and new oil right?

 

it wont be a problem going to r134? How do I go about flushing it?

 

It takes a recovery pump to make sure all the old stuff is out. Then the compressor gets it's oil drained. Then new oil installed. All fittings are checked, and then nitrogen is pressurized into the system to check for leaks. Then a vacuum pump on the system to get all the moisture out, and then the new refirigerant installed.

Everyone thinks the changeover is easy. Sure, it can be, but it may not last.

 

I just meant flushing the valve lol Thank you for answering though, I appreciate it. Im changing over because a fitting came loose and all the r12 leaked out. My dad used to do home hvac and has a vacuum pump and i bought all new seals and a new accumulator. Tomorrow I'm going to buy the refrigerant and oil. For these compressors is PAG-46 the right oil? And would a can of 8.5 oz be ok?

EDIT: I've been reading that orifice tube systems had a drier while expansion valves used an accumulator? Or maybe I have it backwards. Either way my accumulator has a pressure cut off switch thing that is adjustable. How do i adjust it and if that shuts off the compressor when pressure gets too high the will that and the expansion valve be overkill?

 

The simplest is to leave the system original as far as the major pieces go, then you know it will all work. I would adjust the pressure switch only as a last resort, and while watching the high pressure side of the system.

If you are going to run PAG oil, you need to really get all the old r12 oil out of the system. I don't know if you can get it ALL out or not without a lot of trouble. That's why the conversion kits run ester oil, it doesn't react with the old r12 oil like PAG does. The conversion kits come with the r134a and the oil already in the can.

 

So ester oil is compatible with r134a? Is either one better or should I attempt to thorougly flush the system?