Electronic expansion valve

[Stretch79]

Hi guys

Just a quick one Trying to do an L.P. cut out for a major service and was wondering what is the best way to do this seeing as it has an electronic expansion valve.

Obviously mechanical you can pull off and go from there but even when unplugging power to exp it won't go out.

Any ideas please?

Thanks

[Glenn Moore]

What make and model of electronic expansion valve and controller is on the job?.

[Glenn Moore]

It's most likely a stepper valve type and when unplugging the power to the valve the valve will stay in the position it was in when the power was removed. Some controllers have a go signal , by breaking the go signal the valve will be forced closed . So make and model of device will help to advise you

[Stretch79]

Hi Glenn

It's a Trane controller and the exp is a Carel e3v

thanks

[Stretch79]

Hi Glenn

It's a Trane controller and the exp is a Carel e3v

thanks

[FaultCode]

No other liquid line valves about?

Or, do you have the Carel controller clip-on display front end ?

[Glenn Moore]

Hi Stretch
There may be a setting in the Trane controller to force close the eev .Sorry don't know the Trane controller! . What you could try is to run the chiller and let it shut down on its control stat. Then disconnect the cable to the e3v and restart the chiller the valve should stay at its closed position.
Are you sure there is no valves to allow pump down i.e. Condenser outlet etc. Normally with these controllers there is a setting or external switch which allows you to do a pump down and the e3v is held forced closed by the controller keeping a small current on the stepper motor holding it closed.
Ps Stepper motors close when the compressor stops .In the event of a power failure the valve stays in its operating position,some manufacturers install a battery back up to force the valve closed to prevent compressor damage due to liquid slugging under this type of problem. Otherwise a good old solenoid valve is the answer, but I'm sure there is some means to run the machine in pump down mode, hopefully someone else on here can help you.
With the use of stepper motor expansion valves most of the valve manufacturers also produce a battery driven stepper valve driver module for service use , I have used both a Danfoss and Sporlan ones . They are universal as nearly all stepper valves are bi polar type and these battery stepper drivers will be an asset if you get one, they are not cheap , but allow you to manually drive and control the valve from the driver module ,a great service tool for the future generation of stepper valves. If you download the Carel stepper valve brochure it's give the 4 wire colour coding for the various models of stepper valves on the market .Glenn

[Stretch79]

Fault code and Glenn. Many thanks for the advice. I'm not on the site now so can't say about any other valves etc. I will try the suggested next time round and look for any pump down valves. Many thanks gents