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clogged filter/muffler or something else?

vcp90 on Wed June 29, 2011 8:03 PM User is offline

Year: 1991
Make: ford
Model: f150
Engine Size: 351w
Refrigerant Type: r134a
Ambient Temp: 90
Pressure Low: -15
Pressure High: 100
Country of Origin: United States

a year and a half ago i put in an entire new system. remanufactured compressor, drier, condenser, evaporator, and both lines. (one liquid line, one "two in one suction/discharge")

the compressor went out at the end of last year. probably due to me using a crappy "alternative" refrigerant. i was a complete idiot. i will never use anything but pure 100% r12 and r134a. also i think i had it wayyyyyyyy overcharged. this was before i was a 609 and A7 ASE certified tech. now that i know what im doing, i decided to repair this.

i hooked the guages up and with the compressor engaged nothing changed at all. not even 1 psi. pulled the orifice out and complete black death. i flushed the evap and condenser, and installed a new orifice. i vacuumed down to 30 and let it sit till my new compressor and drier come.

i got the compressor and drier today, hooked it all up. vacuumed for an hour, made sure it held for another hour. i charged by vacuum and then started the vehicle and now i get
-15 on the low side and the high side doesnt change at all (switch is jumpered of course).

there is a muffler or filter on the high side line in between the compressor and the high side service port. is that muffler/filter clogged with all the black death crap?

im thinking the compressor must be good because its pulling vacuum but the high side doesnt change at all.

right now i recovered it and am leaving it at 30 inches of vacuum.

do i just need to replace that high side line?

what do you guys think?

mk378 on Wed June 29, 2011 9:14 PM User is offline

Check the orifice again. Probably there's a lot of crud left in the condenser. Lines that have a muffler can't be flushed, must be replaced. With black death you usually replace everything except maybe the evaporator.

HECAT on Thu June 30, 2011 10:55 AM User is offline

Did the crappy "alternative" refrigerant previously used contain any sealer or super performance additives? A filter will be removable/serviceable, and a muffler will not. Is it a tube and fin condenser? If you flushed properly, you should know they are not blocked, right? Mufflers can be extremely hard to flush and dry and condensers can clog with sealers and other incompatible additives; although this more common with the serpentine and parallel flow designs. Additives and alternative refrigerants create chemistry experiments within the system, sometimes forming acids, solids, mud, and "goo". A new line w/ muffler and condenser may be needed.


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vcp90 on Thu June 30, 2011 8:21 PM User is offline

alright. i realized i must not have flushed the condenser because it was entirely full of black goop.

i replaced it with a clean one from a donor truck and put two 12" fans on it.

i flushed everything else except the new compressor, new drier, and the old discharge line due to the muffler. but it was not clogged i blew air through it.

put it all back together, put in brand new red o-tube, vacuumed for 30 minutes and charged it. pressures were right where they should be. but it was 100 degrees ambient and the vent temp was only 81.

the evaporator inlet was cold, the outlet not. i recovered it, and pulled the orifice out to find it 90% clogged with crap (most likely from the discharge line)

i wiped it off(knowing there would be more), and reinstalled it. vacuumed, charged, same thing happened again but it seemed like the last of that rubber crap.

i was all out of red orifice tubes, so i put a blue one in, and vacuumed for only 10-15 minutes. then i charged it. high side was perfect, low was like 5 psi and the part of the line right after the orifice was frozen solid.

i figured it was clogged again so i recovered again and pulled it out. only this time it was perfectly clean! only had fresh clean oil on it.

so as of right now, i put that same blue one back in because obviously all that crap is filtered out, and its sitting at 30 inches of vacuum.

my question is why did it freeze? is there moisture in the system from only vacuuming for 10 minutes (really humid out), or is the slightly bigger blue orifice too big?

i have a feeling it was just moisture, but i wanted to make sure before i have to charge again only to find the same thing.

thanks guys

Edited: Thu June 30, 2011 at 8:25 PM by vcp90

iceman2555 on Thu June 30, 2011 11:12 PM User is offlineView users profile

Ford orifice tubes are notorious for 'freezing' when the system is being charged and the system is undercharged. The 15 min vac is not sufficient to remove moisture.... the possibility of moisture and low charge could result in the 'freeze'.

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vcp90 on Thu June 30, 2011 11:33 PM User is offline

alright thanks. i normally vacuum for an hour and a half, an hour at the least.

but when i was charging and recovering like 6 times today, i got a little impatient. i will put the pump on there for two hours tomarrow, let it sit overnight again at 30, and charge on saturday. hopefully that does it.

vcp90 on Fri July 01, 2011 3:20 PM User is offline

Alright. I vacuumed for an hour and same thing happened. Frozen solid right after the orifice. 5 psi on low side. Pulled outthe orifice and it is clean. What is going on?

JJM on Fri July 01, 2011 8:40 PM User is offline

You could have a restriction after the orifice. With the amount of contamination in the system had in the system, I wouldn't be surprised.

Actually, your method of flushing the system is sort OEM procedure after a failure - albeit with a filter - I guess because they don't want to get stuck with warranty costs for a paint job if a flush goes bad.


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