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Need some AC advice/help EXP VALVE FIXED!!!!!! |
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rushtonmd
AMC Apprentice Joined: Apr/17/2020 Location: San Diego, CA Status: Offline Points: 57 |
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Posted: Jun/10/2020 at 6:01pm |
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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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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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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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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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Heavy 488
AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3557 |
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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4837 |
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I figured that was it. Glad you got it fixed and thanks for reporting back.
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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Texas275
Supporter of TheAMCForum Joined: Dec/18/2013 Location: Forney, Tx Status: Offline Points: 469 |
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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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401MATCOUPE
AMC Addicted Joined: May/20/2010 Location: Salisbury, MD Status: Offline Points: 5367 |
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Okay, is aftermarket changes, I can not help any further.....thank you.
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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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Mopar_guy
Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4837 |
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Back on page 2 "No OEM parts, everything is aftermarket. "
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"Hemilina" My 1973, 5.7 Hemi swapped Javelin |
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401MATCOUPE
AMC Addicted Joined: May/20/2010 Location: Salisbury, MD Status: Offline Points: 5367 |
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Did you change the expansion valve to something other then the original fittings? I am not understanding the issue???
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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
Supporter of TheAMCForum Joined: Dec/18/2013 Location: Forney, Tx Status: Offline Points: 469 |
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The evap is set up as 134. It is a cheap model and I may be paying for that now. I put the numbers that are on the valve into google and it only came back with a few results, all of them overseas, and only a couple in English
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Well it could be defective, as it is a low cost item, that is a wee bugger to get to if all finished up. As for difference yes there is. But most are happy with original R12 valve. If your doing a whole new kit or upgrade, I suggest obtaining R134 valve if possible to swap out. It does make it cooler, as the system does not cycle as much. It should cycle once every 2 minutes, but it depends on capacity and tempratures. Between once every minute or two is good. The less cycling the more efficient the system. |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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