Originally Posted by
mistakenID
I've never had to do anything to my trucks A/C so not familiar with the quirks. I had to look up what the orifice tube was. Always referred to as an expansion valve on my semi's.
There used to be a screen that would get plugged on the expansion valve as the trucks got older and would cause high pressure and lack of cooling.
We always just pulled the screen out, evac the system for 30 mins, let sit for 30 mins to check for leaks and recharge.
Just wondering if the orifice tube can get plugged (partial plugged), and what is the difference in the colors?
This should answer your question about them getting clogged:
http://www.eatoncomp.com/images/1991...3/IMG_0197.JPG
I went with a red orifice tube this time because I read that it has a smaller expansion orifice and works better with R134a. I used a blue orifice tube last time I rebuilt the system simply because that is what it had already. The blue tube has a slightly larger orifice and is good for the original R-12.
Now, my car has an expansion valve. I am getting 40PSI on the low side and 150PSI on the high side. I attribute this to a stuck open expansion valve. I am planning on rebuilding the car's A/C system soon; I just received a bunch of parts for it, so maybe I will work on it this coming weekend.