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Need some AC advice/help EXP VALVE FIXED!!!!!!

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401MATCOUPE View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401MATCOUPE Quote  Post ReplyReply Direct Link To This Post Posted: May/12/2020 at 5:10am
Did you change the expansion valve to something other then the original fittings?  I am not understanding the issue???
Ross K. Peterson
68X,GoPac,343,AT,52A(1stCar)
68X,GoPac,390,4sp,52A
69X,GoPac,390,4sp,64A
70X,GoPac,390,4sp,87A,8
70X,GoPac,390,4sp,BBO,8
70 Jav SST,390,AT,BSO
74MatX,401,AT,Prototype
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Mopar_guy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mopar_guy Quote  Post ReplyReply Direct Link To This Post Posted: May/12/2020 at 8:14am
Originally posted by 401MATCOUPE 401MATCOUPE wrote:

Did you change the expansion valve to something other then the original fittings?  I am not understanding the issue???

Back on page 2 "No OEM parts, everything is aftermarket. "

"Hemilina" My 1973, 5.7 Hemi powered Javelin
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401MATCOUPE View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 401MATCOUPE Quote  Post ReplyReply Direct Link To This Post Posted: May/12/2020 at 11:21am
Originally posted by Mopar_guy Mopar_guy wrote:

Originally posted by 401MATCOUPE 401MATCOUPE wrote:

Did you change the expansion valve to something other then the original fittings?  I am not understanding the issue???

Back on page 2 "No OEM parts, everything is aftermarket. "

Okay, is aftermarket changes, I can not help any further.....thank you.
Ross K. Peterson
68X,GoPac,343,AT,52A(1stCar)
68X,GoPac,390,4sp,52A
69X,GoPac,390,4sp,64A
70X,GoPac,390,4sp,87A,8
70X,GoPac,390,4sp,BBO,8
70 Jav SST,390,AT,BSO
74MatX,401,AT,Prototype
74MatX,401,AT
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Texas275 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Texas275 Quote  Post ReplyReply Direct Link To This Post Posted: May/17/2020 at 4:08pm
Finally got back to the shop with an expansion valve that fit. Evacuated the system, recharged, and it works great.  Thanks so much for helping me fix it!!!! Y’all are the best!!

Tom
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mopar_guy Quote  Post ReplyReply Direct Link To This Post Posted: May/17/2020 at 5:08pm
I figured that was it. Glad you got it fixed and thanks for reporting back. Thumbs Up

"Hemilina" My 1973, 5.7 Hemi powered Javelin
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Heavy 488 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heavy 488 Quote  Post ReplyReply Direct Link To This Post Posted: May/17/2020 at 7:56pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: May/18/2020 at 3:02am
It is important that the thermal bulb of the expansion valve is attached firmly and directly to the outlet line of the evaporator then wrapped in insulation. Without this, the expansion valve will think the evaporator outlet is warm and the valve will open wider to admit more refrigerant. High side pressure will drop, low side pressure will rise, and the compressor will slug with liquid refrigerant. You will eventually blow the compressor.

R12 and R134a expansion valves have a slightly different superheat setting but only slightly and not enough to cause this.

There is also the question of system charge amount. Even with a wide open expansion valve, there should not be any bubbles in the sights glass while the compressor is running. Charge amount does not effect the cooling effectiveness of expansion valve type A/C systems. All they care about is that there is enough refrigerant to keep the pickup tube in the receiver/dryer submerged in liquid refrigerant. Adding refrigerant just raises the liquid level. Bubbles in the sight glass means the pickup tube is not submerged, so you add refrigerant until the bubbles disappear then add a little more to give it some reserve.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rushtonmd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/10/2020 at 6:01pm
Good call on the expansion valve. I built a custom AC system for a VW and the expansion valve that I got from the company was sized too small for the system. It was a 1ton valve - I did the same thing where I trolled the Oreilly site until I found a 1.5 to. valve with the correct fittings and it all worked great. A lot of AC system companies sell the same valve for all systems and it’s good to check the size against system size - but also they’re super cheap which is nice :) I think mine was like $15. 

One other thing is there are metric fittings as well as AN fittings so sometimes you’ll have to mix and match with adapters or make sone adapter hoses.
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