Toshiba Cassette R407c issue!

[24057]

Good afternoon all, firstly I'm new here so be nice! :) (as i'm sure you will be)


Now, bare with me on this one as it may seem a little vauge due to the fact I'm primarily working on Daikins, so im not so familiar with other systems etc.
Received a call from a customer of ours complaining his Toshiba R407c Cassette isn't heating and there is a small icon displayed on the controller (presumably defrost) that isn't going away. I doubt it's a fault code as they're hidden until you press 'check'. The unit has previously been on heating throughout the cold season, so it's something that's happened randomly. Now my plan of action upon arrival is to check for faults and try to run on test cooling and see what happens.
I suspect that it may have a gas leak, so is unable to defrost outdoors correctly, if not I was thinking there's a possible outdoor TD thermistor error or pcb defect etc? What are your thoughts? I appreciate the fact that this is very vauge due to the fact I don't have access to the serial number, or present faults. Also it may not even have an LP switch due to its age. Any help would be greatly appreciated! :)

[install monkey]

short of gas probably, will show preheat symbol until indoor coil reaches 30deg then sign will dissappear and indoor fan will speed up, see manual attached
http://www.mediafire.com/view/?4czoj724ws1bg79

[The Viking]

First thing first,

After you checked that the compressor is pumping check and verify the charge.

Happy hunting.

:cool:

.

[24057]

Thankyou gentlemen! Thant's what im hoping for!
I shall update when I attend site on Wednesday!

[24057]

short of gas probably, will show preheat symbol until indoor coil reaches 30deg then sign will dissappear and indoor fan will speed up, see manual attached
http://www.mediafire.com/view/?4czoj724ws1bg79

Thankyou for this, fingers crossed it'll be short of gas with an obvious leak. If not, and the preheat symbol continues to display, with the indoor fan not running, do you think it would be possible that the indoor coil thermistor has packed up? If so, according to that manual it says it should measure 12 ohms roughly. Thoughts on this?

[24057]

any thoughts are appreciated btw!

[install monkey]

stick a thermometer in the evap coil and run the bugger in heating- if coil doesnt reach 30 deg after 6 mins approx then s.o.g if it goes over 37deg then coil sensor :cool:

[24057]

Hi all, attended site today and found the following...
Looked at the controller to see 'defrost' and 'pre heat' (or whatever it's called) icons showing meaning coil isn't upto 30 deg c and outdoor needed to defrost. Went outside to find no ice on the coil apart from two separate bands coming off the coil distributor lines (indication of lack of gas). Checked the flares indoors and outdoors then checked the condenser internals by removing case etc and found no traces of leakage. Went back inside and pressed 'check' to see faults and it was clear. After a while the indoors finally ran, i measured the air off the indoor coil at 24 deg c, way below what it should be on flat out heating. Went outside to make sure compressor and all components etc were running ok and they were. The condensing fan was blowing off cold air meaning the unit is 'working' but not as well as it should be. I suspect that everything is mechanically ok, but it's just lacking gas meaning it's not achieving its full duty. I've said that it needs gas removing and weighing. Thoughts?! I'm going back to site tomorrow!

[24057]

Hi all, attended site today and found the following...
Looked at the controller to see 'defrost' and 'pre heat' (or whatever it's called) icons showing meaning coil isn't upto 30 deg c and outdoor needed to defrost. Went outside to find no ice on the coil apart from two separate bands coming off the coil distributor lines (indication of lack of gas). Checked the flares indoors and outdoors then checked the condenser internals by removing case etc and found no traces of leakage. Went back inside and pressed 'check' to see faults and it was clear. After a while the indoors finally ran, i measured the air off the indoor coil at 24 deg c, way below what it should be on flat out heating. Went outside to make sure compressor and all components etc were running ok and they were. The condensing fan was blowing off cold air meaning the unit is 'working' but not as well as it should be. I suspect that everything is mechanically ok, but it's just lacking gas meaning it's not achieving its full duty. I've said that it needs gas removing and weighing. Thoughts?! I'm going back to site tomorrow!

I've spoke to Toshiba and they believe its more likely to be the expansion valve. I couldn't see it frosted up, but it may of gone open circuit or is stuck in its current position.

[The Viking]

First thing first,

After you checked that the compressor is pumping check and verify the charge.

Happy hunting.

:cool:

.


I've spoke to Toshiba and they believe its more likely to be the expansion valve. I couldn't see it frosted up, but it may of gone open circuit or is stuck in its current position.


First thing first,

After you checked that the compressor is pumping check and verify the charge.

Happy hunting.

:cool:

.

[install monkey]

to change the expansion valve ur gonna have to remove the charge, if different then try it with a full charge and see what happens
toshiba technical was renound for quoting, have u comfirmed the gas charge

[24057]

to change the expansion valve ur gonna have to remove the charge, if different then try it with a full charge and see what happens
toshiba technical was renound for quoting, have u comfirmed the gas charge


No I havn't confirmed the charge, when I replace the expansion valve I will weigh the gas iv'e removed and replace as required. I imagine the TEV phial is misreading or the valve is knackered in addition to being slightly low on gas.

[jdunc2301]

my vote short of gas! Doubt the expansion device

[24057]

well, I obviously thought that first, but I couldn't find a leak anywhere. Unless there is a seeping braze in the pipework but I doubt it. The new TEV is only £20 odd believe it or not. So when I remove the gas if its significantly down on charge I will just add new gas and try that, before going to the effort of replacing the tev.

[jdunc2301]

at £20 thats not bad!

[24057]

I know, craziness! Nothing to lose really. Either top up gas or top up and replace tev. Both require the removal of gas so fingers crossed itll be ok. Should point out im only 19, so my knowledge is intermediate. I got my lifetime f gas ticket when I was 17! I also have my NVQ ETC, but I don't work on Toshibas much, I stick to Daikins what im more experienced with. Although i work for my dad so we do other stuff too, heating, gas clean rooms, AHU's and compressed air lines and general mechanical services. :)

[jonjon]

Just repaired 2 407c units today with similar faults found a leak on one of the pipes on the 4 way valve.

[24057]

Just repaired 2 407c units today with similar faults found a leak on one of the pipes on the 4 way valve.

Ok, thanks for that. I didn't notice any oil residue inside the condenser, or smell anything oily. But it's worth noting, i'll double check when I go! :)

[install monkey]

i had a 3.5kw mitsi with a leak on the 4 way valve- a tiny leak which didnt show any oil- found it with glostick