Kelvinator split system, works on cooling but lines frost up on heating

[alan_man]

Hi fellas, as the title suggests I have a problem with a Kelvinator split system. Basically the unit works fine in cooling mode, appropriate refrigerant level (R22) both indoor and outdoor fans work fine etc. However once heating mode is selected and the compressor starts up almost instantly both high and low lines begin to frost up and will continue doing so rapidly until the system is turned off. Outdoor fan runs, indoor wont (as they all do this). Once the unit is switched to cooling it will work fine again then have the same issue on heating. The indoor unit power operation light is lit like usual as well as what seems to be the system defrost icon. Ambient temps are nothing out of the ordinary for location (around 12C outside), no air restrictions to each unit at all. I figure it may have something to do with the reversing valve/solenoid, can someone confirm this? Also is there a way to test out the solenoid and valve itself? thanks in advance

[Brian_UK]

Sounds like the reversing valve isn't changing over properly or there is a non-return valve that may be stuck.

Check voltage to the valve coil and also try a magnet on it.

You say that the gas level is OK but if it is slightly low you may not get sufficient pressure to move the reversing valve.

[alan_man]

Ok thanks for that, I understand the operation of the valve (relies on hot vapour through small capillary to shift valve position by coil operation) how ever where are these non return valves usually located? As your sig suggests perhaps a small tap with a hammer handle may free them up?

[paul_h]

You need to work out if the problem is electrical or mechanical.
First off check the coil to find out if it's good or open circuit.
If good, then check to see if it's getting power.
If that's good, and/or you hear the solenoid 'click' in heat mode, then the problem is mechanical.

Most likely the reversing valve seized. Even if you do support it well, while hitting the valve with a soft mallet in the right direction and it does switch over, so you don't damage the pilot tubes, kink or break any piping etc etc, it needs replacing anyway.
There's so many switch overs it has to do each time it heats or defrosts, it's going to fail again very soon anyway.
So what I'm saying is there's not point trying to hit it with a mallet. Electrical fault repairable, mechanical fault replace the reversing valve or the a/c.
Non return valves are where the capillary or mechancal TXV/ATX/Fixed oriface is.

[alan_man]

Thanks, everything mentioned makes sense there. I understand the valve would most probably fail down the track I would just like to nut the issue out and know for next time if I ever come across the same issue. I am able to see the unit in the next couple of days which I might go do, no point replacing valve as it's probably more cost effective to replace complete unit. Out of sheer coincidence, having similar issues with an old Sharp hand-me-down unit I recieved a while back which I "set up" in the back shed to see how it works. The unit is doing very similar, fine on cooling but only just working on heating. Connecting pipe work is not freezing up, larger line (hi side on heating) very warm to the touch while low line only just above ambient. The complete outdoor coil is freezing up but thats it, I know reverse valve and coil is definately working, very audible click and gas hiss from when I switch over to cooling at which point the whole frozen coil instantly defrosts. Seems like a blockage in the indoor unit coil, got me stumped

[paul_h]

T no point replacing valve as it's probably more cost effective to replace complete unit.
Of course, that's why I said replace valve or replace a/c.
I wouldn't hesitate to replace the whole unit if it's a Kelvinator wall split and needed a r/v. Only ducted a/cs would I bother replacing an r/v. That's mainly because there's a 5 yr warranty here and most a/cs with an r/v problem are over 10 years old, and kelvinators are either just old rebadged old LGs or they are cheap chinese stuff.

The sharp it's either blockage, short of refrigerant. If blockage more likely in the outdoor unit where the capillaries are.
the indoor unit pretty much has nothing smaller than 3/16", outdoor has the capillaries, check valves and strainers, so problem more likely in the outdoor unit.
The only other thing to normally check is the installer hasn't kinked the 'suction line' though.

[alan_man]

Interesting, might do some more investigating on this sharp while its set up in the back. BTW refrigerant level is good, as well as air flow etc. Mind you this thing is getting on so wouldnt surprise me if it had some build up in the lines somewhere. Thanks again for the help