Automotive Air Conditioning Information Forum (Archives)
How bad did I mess up?
TimZ on 
Wed August 26, 2015 9:23 PM 
Year: 1996
Make: Chevrolet
Model: Suburban
Engine Size: 350ci
Refrigerant Type: r134a
Ambient Temp: ?
Pressure Low: ?
Pressure High: ?
Country of Origin: United States
I'm refurbishing my '96 Suburban's A/C by replacing everything in front of the firewall -condenser, lines, accumulator and compressor. I flushed the front evaporator and in my haste attempted to flush the lines to the rear evaporator, applying pressure/solution (NAPA A/C solvent) to the low side without much success of blowing it through. I then applied just air through the high side and what I loaded up in the low line came out. Of course, I checked the forum AFTER my failed attempt and read where those lines should not be flushed. My question is, have I caused any damage to the rear lines by introducing the solvent? Thanks.
TRB on Wed August 26, 2015 9:28 PM 
Harm the lines no. Any flush left in the system will break down the oil and cause a compressor failure.
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Contact: ACKits.com
TimZ on Thu August 27, 2015 12:28 AM
TRB - Thanks for the reply. When I put the solvent in through the low side, the pressure built up and blew back out. (It didn't blow through the high side.) Thats when I blew air through the high side to get out the solvent. Is there a check valve on the low side? I'm hoping the solvent didn't make it to the evap. and the air was sufficient to clear the line. Do you think that is a safe assumption? I just don't want to open a can of worms by trying to break loose the fittings at the rear evap.
Jag987 on Thu August 27, 2015 12:35 AM
My thoughts, if the front needed to be flushed, so does the rear. Otherwise only half the system has been cleaned. There is no check valve, but the rear expansion valve may be acting as one and letting air flow through easier one way than the other.
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I bought a can of 134a at w**-mart that had a stop leak, oil, and dye in it. It also had a hose and a gauge, so now I'm an AC pro!
TRB on Thu August 27, 2015 1:31 AM
jag987 is on the money, if you failed to remove your expansion device on the rear system. You have flushing agent in the lines still as well as the evap core. People always want to do things the easy way and wonder why it fails.
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Contact: ACKits.com
HECAT on Thu August 27, 2015 7:50 AM
QuoteOriginally posted by: TimZ
TRB - Thanks for the reply. When I put the solvent in through the low side, the pressure built up and blew back out. (It didn't blow through the high side.) Thats when I blew air through the high side to get out the solvent. Is there a check valve on the low side? I'm hoping the solvent didn't make it to the evap. and the air was sufficient to clear the line. Do you think that is a safe assumption? I just don't want to open a can of worms by trying to break loose the fittings at the rear evap.
Unfortunately it is not a safe assumption. The oil you wanted to remove is now a oil and solvent mix that is now even more critical to remove. With all the new parts you have, it would be wise to get a new rear TXV (you have a new OT for the front, right?). Open the can of worms and remove old TXV, then flush and dry out the rear Evap. Take the time to ensure everything you are reusing is clean and dry; or you may be just sacrificing all the effort and new parts. Some TXV's do have backflow prevention, and will throttle closed under 30-40 lbs. of backpressure.
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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.
FLUSHING TECHNICAL PAPER vs2.pdfÃÂ
TimZ on Thu August 27, 2015 10:12 AM
Thanks guys. I will heed your advice. Any suggestions as to how best to loosen the fittings at the rear evaporator? I had to cut radially into a couple of the steel nuts on the front, which I didn't mind doing because I was replacing the lines anyway. I really don't want to sink the $ into replacing the rear lines, so I would like to preserve them. My thought is to use my Dremel wire wheel to clean up around the fittings and then soak them in Liquid Wrench. ?
HECAT - what does replacing the TXV get me? Do they just go bad? Yes, I am replacing the OT (orifice tube?).
"Where there is no counsel, purposes are disappointed; But in the multitude of counsellors they are established." Prov 15:22
AC_Doc on Thu August 27, 2015 11:25 AM
It's more what NOT replacing the TXV might get you.
The TXV, like the Otube, has a filter screen and a small hole (orifice) to control the refrigerant flow.
If the screen is full of debris it will inhibit flow and if any crud gets through it, it could restrict the orifice.
TXV's are cheap compared to a total redo because the old one didn't work.
Why take the risk??
Ac_Doc
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Sometimes you must accept things at faith value!
TimZ on Thu August 27, 2015 5:11 PM
Thanks Doc. Just ordered the TXV from the dealer. Hopefully it will be here by Saturday. Has anyone used a "freeze" type product that comes in an aerosol can for breaking loose fittings? I read where aluminum expands and contracts more than steel with temp changes. The theory is that the aluminum will shrink more than the steel nut when it gets cold to make it easier to break it loose. ???
Dougflas on Thu August 27, 2015 8:46 PM
Breaking them loose can be a bear. Use a solvent ( I use Kroil), let it set a while, spray more, use a heat gun or hair drier, more solvent, and then heat again. try to rock the fittings back and forth. Take your time. Anothwer method is to use a dremel tool and drill a small hole into the side of the nut and expose the threads. squirt solvent in there and try the soak, heat, soak, heat and rock method again.
Good luck.
HECAT on Thu August 27, 2015 9:57 PM
There is this 10 year old post in "procedures"; but the link does not appear to work anymore. Doug's advice is great.
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HECAT: www.hecatinc.com You support the Forum when you consider www.ackits.com for your a/c parts.
FLUSHING TECHNICAL PAPER vs2.pdfÃÂ
TRB on Thu August 27, 2015 11:09 PM
Fixed it Hecat.
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Contact: ACKits.com
TimZ on Fri August 28, 2015 12:30 PM
Thanks guys for all the helpful info. Its a lot easier to tackle this stuff when you're not going in blind. I did use the drill method on a couple of the front connections, but to no avail. I may have been too impatient. Thanks Doug for the method you outlined. I'll give it a try with the heat and rocking them. Is Liquid Wrench an inferior product compared to Kroil and some of the other solvents/penetrating oils?
Dougflas on Fri August 28, 2015 6:23 PM
I have never had a problem with Kroil. I HAVE had liquid wrench not work. Kroil actually creeps into the fitting threads. Do a Google search on Kroil.
TimZ on Sat September 05, 2015 12:00 PM
Alright. I've tried the soak, heat, soak, heat and rock method and it loosened the threads. The problem is where the aluminum tubing meets with the steel nut is seized. The vertical position of the lines (going into the rear evap) doesn't let the PBlaster soak in. Did my best to clean out the joint (used a straight pin to clean out the corrosion between the tubing and the nut).
I put some pics here. http://www.withallthymind.com/96suburban/ac.htm
I would try the drill method on that end of the nut, except there is no forgiveness with the aluminum tubing. Any suggestions?
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