Automotive Air Conditioning Information Forum (Archives)

Provided by

We've updated our forums!
Click here to visit the new forum

Archive Home

Search Auto AC Forum Archives

Are expansion valves specific for R12 or 134?

PoodleHead on Sun July 08, 2007 9:10 PM User is offline

Year: 1992
Make: Acura
Model: Legend
Engine Size: 3.2
Refrigerant Type: R12
Ambient Temp: 85
Pressure Low: 42
Pressure High: 205

The reason I ask is I still have vent temps that are too warm and get warmer on high fan speed. This is after adding another ~ 6-8 oz +/- of R12. The LP is about the same and the HP side changed from 185-205 while the vent temp remained a constant ~68.

I replaced the EV with an aftermarket one and it wasn't the one called for in their book. The one called for in their book had the wrong size fittings. They finally went into the back with my EV and matched it up. It was Frigette 208-307 (Replaces Four Season 39059) so I'm wondering if this one is specifically for 134 maybe and I just need to take it like a man and get one from the dealer?

mk378 on Sun July 08, 2007 11:58 PM User is offline

There's very little difference in the operating point of the two refrigerants. Newer valves are a compromise that will work with either.

It is very important when replacing an expansion valve to get the temperature sensor part firmly attached to the evaporator outlet pipe same as the original was, and insulate it from outside heat.

JJM on Mon July 09, 2007 12:13 PM User is offline

If you go to the dealer, you'll likely get a TXV calibrated for R-12 - which is fine, because as MK378 correctly notes, the differences are insignificant for R-12 or R-134a.

But there are differences in TXV's for different applications; TXV's are VERY vehicle specific. I wouldn't go with so called "universal" TXV's.


PoodleHead on Mon July 09, 2007 1:24 PM User is offline

I've got the bulb attached to the line and insulated very well so I don't think that is the problem.

I just talked to the people where I bought this EV and he said the new valves have 134 in the bulb. Since I wasn't able to get the correct valve off the shelf without it having to be matched up with the physical looks of my valve, I think I wll get it from the dealer. I hate to pay the extra cost, but it would be well worth it to have this *%#&^ finished! Thank you!

JJM on Mon July 09, 2007 1:55 PM User is offline

While you're there, pick-up a receiver dryer too, if it hasn't been replaced already. After 15 years, the original one is certainly done.

Let us know how you make out after the OEM TXV from the dealer.


PoodleHead on Mon July 09, 2007 7:27 PM User is offline

I did replace the receiver dryer when I replaced the evaporator and fixed all the leaks. I wish at that time I had put an Acura EV in, but it looked clean so I left it alone. Then when I tried charging is when there was a blockage and the only thing that hadn't been replaced or flushed was the EV so I replaced it with the aftermarket one (I didn't replace the dryer at that time since it was basically new). That got rid of the blockage, but now this problem.

I'll price the dryer from the dealership and may get that too just for added insurance. It's going to be at least a week because I order parts from Acura of Augusta at a significant discount. That will give me time to 'cool' off, find a place to recover the R12 and while I'm at it, I'll probably pull the lines and flush them and the condenser again... Thank you for the help and advice.

PoodleHead on Sat September 29, 2007 11:10 PM User is offline

I'm back after a long delay due to my Mother getting West Nile virus and having her Memorial Service this past weekend...

Well I didn't have to worry about recovering the R12. It leaked out through the *%$# schrader valve on the high side. I learned a lesson there; always when disconnecting gauges on an R12 system, spray a little soapy water on the fittings... Anyway, I put the new factory exp valve in along with a new drier (drier I pulled out had NO oil in it). I'm getting good vent temps now when the air flow is on recirc. If it's on outside air, it's about 20F hotter. Not sure why that could be.

Pressures and temps with recirc on/off are:
26 160 40 F recirc ON
41 175 61 F recirc OFF
Ambient = 88 F

I'm going to let a sleeping dog lie for now, but I am curious about the recirc problem. I may have too much mineral oil in the system by about 3 oz. I thought all extra oil would sit in the drier, but that's not the case. I cut one apart and the pick up tube is all the way at the bottom of it. I just wish I had checked before I added oil and installed the new one...

Thanks a bunch for everyone's help!

Back to Automotive Air Conditioning Forum

We've updated our forums!
Click here to visit the new forum

Archive Home

Copyright © 2016 Arizona Mobile Air Inc.