Advanced AC question

[thorsen]

I started disconnecting my AC system to prepare for flushing the system (I found the leak from earlier - thanks!)

My expansion valve has HFC-134a printed on a label. The compressor still has the R-12 fittings, so I am unsure if the system was retrofitted. What happens if I use Freeze 12 with a 134a expansion valve?

What is the difference between an R-12 and R0134a expansion valve?

[OldPokey]

Freeze12 is 80% R134a - so you're not getting much of an advantage by using it instead of the real thing. To do a proper conversion to R134a you will need to replace the condenser up front with something larger (it will perform better), replace hoses (which you want to do anyway unless they've been done in the last few years), flush the system thoroughly, install a new receiver dryer, and pull a vacuum on it for a good long time to boil out all the humidity.

The difference between the R134a and R12 valve is the fact that they are designed to work with two different refrigerants. R12 boils at -22 degrees Fahrenheit while R134a boils at -16 degrees Fahrenheit. Because of this, the pressure inside the system under R134a is higher, and the expansion valve has to account for that.

[thorsen]

Thanks. Looks like I am going to go down the 134a road then.

I have found a place that makes AC hoses - but how can I tell if my fittings are standard or metric?

[sjefke]

The hose shop should be able to tell. They could also put new hoses on your existing fittings. That's what I did with my old 250C. Existing fittings crimped on new hoses by pro shop. Worked great.

Good luck,

Bert

[alabbasi]

Yep, you want new hoses, R134 hoses are lined because the molecules are smaller. Using R12 hoses will result in a leaky system.

[thorsen]

Bert, Kind of hard when the hose shop is on-line

I ended up making a $20 investment and bought one of each size fitting. That should help me figure out what sizes I need.

[thorsen]

Originally Posted by thorsen

I have found a place that makes AC hoses - but how can I tell if my fittings are standard or metric?

For future reference, go to www.truckair.com and click on the link for "fittings"; they have a great primer on sizing fittings. In a nutshell, measure the outside diameter of the male threads - 5/8" = #6, 3/4" = #8, 7/8" = #10, and 1-1/16" = #12.

Also, http://www.rayeveritt.com/Parts/Hoses/Hoses.html is great for making hose assemblies and purchasing fittings.

http://www.ackits.com/ is a great place for parallel flow condensers and replacement rotary compressors.

http://www.acsource.com/index.asp is a great resource for fittings, tools, etc.