Coil restriction...Opinions needed

[jaxman]

This will prolly keep me up thinking about this all so might as well share it with you all....avid reader and first post. Im a tech with around five yrs exp and still a noob and learn and read this forum pretty much everday, anyway to the problem.

Went on a return call today from our PM tech, he had a a/c with low pressure @ 200/40. Calls me up and tells me he tried to charge and no pressure change and then ran out of freon. No idea how much he put in either, he has no scale.

so go there today and find this
compressor at 13.8A
ambient 80
liquid is 220psi and 80 degrees
vapor 34psi and 49 degrees

s/c 28
s/h 38

temp drop on coil is 72 in 64 out 8 degree delta and cap. tubes are icing, a-coil otherwise is basically warm and dry.

This is a Rheem 4T 12 seer condensor with a 3.5T ICP coil with TXV, coil was existing and we ran lineset ( I think) and set condensor and only 8 months ago. Anyway I know thats not every thing...airflow is good, lineset not kinked, coils clean and low humidity.

So what Im thinking is a stuck almost closed TXV or god-forbid a plugged coil, also has a filter dryer but I think blockage is in the coil.

Any ideas before I yank the coil/TXV on Monday....anything Im over looking? All help greatly wanted and highly appreciated!

[Edwards Htg & Clg]

I ran into almost the same thing today. Heil 12 seer split heat pump running 205/32 with icing at the TXV. Warmed the bulb in hot water, switched to heat a few times and no change. Changing the TXV tomorrow.

[bb]

Sounds like a TXV bulb lost it's charge. Change it. Make sure the bulb or txv body doesn't overheat when brazing.

[chicago tom]

What position is the bulb in?It never be at the bottom of the line,because the oil traveling with the refri.could act as an insulator and the bulb may not sense the refri.temp.leaving the coil.Put it at10 o clock or 2 o clock position.make sure you don't have a restriction at your new connections.

[beenthere]

Pull the sensing bulb and put it in warm water and see it it feeds more refrigerant.

Sounds like trash got to the txv, or the bulb lost its charge.

Disable the blower, and see if all the distributors are frosting the same.(they're distributor lines, not cap tubes)

[jaxman]

Thank you all for the replies, yes the bulbs at 10:00 but the h/o needed to leave so I didnt get a chance to test the bulb. I did tap the txv to see if it was stuck, figured might get lucky. Question for beenthere: what exactly will that tell me to watch the distribution lines for icing....am I understanding correctly that if 1 ices faster there may be a blockage there?

[pipedope]

the blockage is the txv resticting flow of refrigerant into the coil which will freeze the distributer lines. sounds like a bad txv. when you replace it put the nex filter drier right b-4 the new valvealso.

[smokin68]

You're right if one ices and the rest dont its restricted. but I'd pull that txv and check it before thinking the coil's blocked. Most trash should get caught in the txv's screen or their old as dirt(like mine) and have no screen then the trash will just screw up the txv itself.

[ultratec]

As beenthere said, its a Txv (or in let stariner is clogged). Most Txv failures are powerheads or inlet stariners. Just replace Txv at this point.