Tev

How can you see if a TEV is working ok. I have de-gassed the system ,but i think the TEV is partially blocked, how can i check before i re-gas the system

Was the TEV working before you took the gas out of the system?

Why have you taken the gas out ?

Is the TEV fitted with flares or is it sweated in ?

If it is flares then take it out and check that the strainer is clear.

If you are not sure whether the TEV is working or not take a breath and decide if it would be cheaper in the long run to replace it anyway.

it will be partly blocked otherwise it wont work,its a restricive device,it all sounds a bit vauge to tell,just gas it back up and if nothing is passing through it[you can hear it] or the back pressure fails to rise then thats a good excuse to bin it.

If it's a Danfoss TE..2 or a copy Alco with the removable orifice, then you can see if there 's gas in the sensing bulb by inserting the orifice in the valve body.

Then, the orifice must have a space of +/- 1 mm of it's seat and if you push a little bit further till the orifice pushes completely against the seat, then you can feel the spring pressure of the bellow pushing the orifice open.

Othe brands.. you can't see it.
It can be blocked due to moisture.
It's in fact easy to check if it works OK...if the valve has worked well before, open it completely and count the turns you open it.

You will have then full flow. Do this for some seconds and re-close it afterwards with the same turns you turned to open it.

The SH must stabilise to 5 to 8 K. If it doesn't then take no risk, replace it.
If the SH gradually increases, then you have a chance that moisture has entered the system.

When I doubt that mositure has entered the system, then one of the first things I do is looking if the LP cut-out cuts out above atmospheric pressure. Otherwise, moisture can enter very easy the system.

If LP is set below atmospheric pressure, then there's a great chance that there's mositure in the system and that there's also a leak; perhaps a small one in the low side of the system.

Look (=measure) then also for non-condensables (air) in the system and remove this air out of the system.

If you suspect moisture in the system, you can always verify this by heating gently the valve body with a heat gun or a small flame (I did it in the past with my halon leak searcher, the burner type which many young techs never have seen before, and which was the best leak searcher ever made)

Why you suspect on TEV?
Which simptoms machine have?

Renato