Expansion valve r12 vs r134a volvo

1988240DL on Sun May 13, 2012 5:22 PM

Year: 1988
Make: volvo
Model: 240 DL
Engine Size: 2.3
Refrigerant Type: r12
Country of Origin: United States

Just ordered an expansion from volvo oem for my 1988 240 dl and noticed it was stamped with r134a. Did some research and r12 and r134a are different. I will be using r12 on my car and wanted to know if the cooling will get affected. Supposedly r12 specific expansion valves are no longer produced? I found this post and the guy noticed his temp were subpar due to a r134a expasion valve in his r12 system. Text
Anyone know where I can get a r12 specific expansion valve.

mk378 on Sun May 13, 2012 6:46 PM

New valves can be used with either refrigerant. The difference in temperature / pressure characteristic at evaporator conditions is very small, probably within the manufacturing tolerance of the valves. (In the condenser it is a different story. R-12 does condense much better in an inadequate condenser).

I note in the summary on the first page that his system didn't work very well with R-12 and an R-12 valve until he did some other stuff. When replacing the TXV it is very important to install the sensor bulb properly.

Unless your original TXV is clearly bad you can probably reuse it. It's a part that either works for a long time, or it doesn't.

Edited: Sun May 13, 2012 at 6:48 PM by mk378

bohica2xo on Sun May 13, 2012 6:58 PM

The valves work just fine on R12. That beeemerrweenie wasted a lot of time & bandwidth on nothing. I could have adjusted his TXV in the time it took to skim that.

At the target temp of say 35f R12 is @ 32.6 psi & R134a is @ 30.4 psi Most refrigeration gauges are +/- 2% of full scale, and are not capable of resolving that pressure. If you really think it needs more flow, most TXV's are adjustable for superheat as well.

Put the 134a valve in your Brick, it will be fine. If you have a measurable loss of performance, then check the inlet & outlet temps on the evaporator tubes and adjust the TXV.

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

1988240DL on Sun May 13, 2012 7:49 PM

Quote
Originally posted by: bohica2xo
The valves work just fine on R12. That beeemerrweenie wasted a lot of time & bandwidth on nothing. I could have adjusted his TXV in the time it took to skim that.

At the target temp of say 35f R12 is @ 32.6 psi & R134a is @ 30.4 psi Most refrigeration gauges are +/- 2% of full scale, and are not capable of resolving that pressure. If you really think it needs more flow, most TXV's are adjustable for superheat as well.

Put the 134a valve in your Brick, it will be fine. If you have a measurable loss of performance, then check the inlet & outlet temps on the evaporator tubes and adjust the TXV.

B.

On the 1988 volvo the expansion valve is non adjustable, but thanks for clearing this up guys. I will install the r134a valve. Any truth to the post? Later he installed a specific r12 expansion valve and had cooler temps?

Edited: Sun May 13, 2012 at 7:58 PM by 1988240DL

Dougflas on Sun May 13, 2012 9:04 PM

ctually, the TXV's are adjustable. You would have to recover the refrigerant and remove the TXV. There is a hex adjustment in the line. It would actually be a hit and miss to get it corectly adjusted. As mentioned, just use the new valve as is.

JJM on Sun May 13, 2012 9:42 PM

Since you're looking to use R-12, I assume there are no, "Save The Whales", "Bush Lied", "Free The People of Darfur", and "Obama 2012" bumper stickers on this vehicle... all of which would be pretty rare for a Volvo.

Ironically, it was the Volvo driving types that pushed for the ban on R-12, so this post is kind of funny.

You probably would have to find a Volvo NOS part for R-12 specific calibration, but seriously you shouldn't sweat (no pun intended) the small superheat difference between the two. If your final vent temps are more than 2F off with an R-134a calibrated valve I would be surprised.

Joe