im thinking you have a restrcted evap coil. clogged orfice or bad txv valve. or oil trapped in evap. blow the lines with nitro,vac ectt

I am working on a Goodmen heat pump unit. To cut thru the chase, When first starting, head pressure and suctiion pressure are normal. As the unit continues to run, the suction pressure very slowly drops off to 40 psi after about 20 minutes of run time. As this is happening, I notice that the suction pressure is hunting by a pound. I opened up an access hole at the indoor unit and the lines from the TXV to he coils were frozen. Which was expected Could I also have a bad TXV. Any leads will greatly be appreciated.

thanks. especially because the temps are supposed to be a bit more sane this week, I think I can wait until, hopefully, a tech gets out here late in the week. It is able to do some cooling. If you mean to bypass the actual overload PTC on the compressor that is cutting out...no I think that would be insanity. It's there for a reason. Or do you mean another thermal switch? My understanding is code 72 relates only to the compressor itself. There are other messages for other sensors. The troubleshooting guide says: If the control senses the compressor voltage after start--up, and is then absent for 10 consecutive seconds while cooling demand exists, it will de--energize the compressor contactor, keep the outdoor fan operating for 15 minutes (if 230v power present) and display the appropriate fault code. (See table 3) Possible causes are compressor internal overload trip or loss of high voltage (230V) to compressor without loss of control voltage. Now the interesting thing is, before I replaced the contactor, I was getting a lot of "no 230V to compressor" messages, in addition to the thermal cutoff messages. Now I'm just getting the thermal cutout messages. The control board on the outside unit has two leads that attach across the common and the start coil of the compressor, to detect the voltage. So I think if you are just getting the thermal cutoff message, it somehow detects that 230V is still on the line (contactor working), but there's no current flow in the windings because the internal overload is engaged. BTW years ago when this unit first started having trouble, I did get 82 codes (back then, the guy said it was the capacitor but I'm not privy to how he tested it) 82 is what happens when you have 4 consecutive 72s. These days I shut it off at the first 72 code and let it cool down. Now that I think about...Occam's razor at work...that could be it all over again. Maybe even though the cap. tests ok, it isn't.

"It's 3 yrs old and has never been serviced so any damage from cleaner would have been prior to install." Regardless how old the coil is,it has been rode hard and hung up wet somewhere along the way. Notice dents/worn grooves in u-tubes,different appearance between inner and outer fin surfaces. What's up with one gleamy u-tube among all the others with corrosion? I've seen some A-coils and stand by my origional observation "The coil looks to be dirty or damaged ". All that may have noting to do with the problem you are experienceing but might beg the question of what else is hiding in plain sight. All this is mute anyhow since a tech is sceduled to look at it.