Compressor won't start

[dan281183]

Hi i have a problem. I have been working on a walk in freezer i have installed a new compressor and electrical for it but the compressor won't go. It is single phase when i turn it on all that happens is the thermosat/overload keeps clicking every 10 seconds or so the Evap and condensor fan are running but that is all i have tried a 2nd new compressor but still now joy. Hope some one can help.

[monkey spanners]

What was wrong with the original compressor? What sort of compressor is it, csr, csir? What sort of relay does it have? Have you checked the capacitor to see if it is ok? Is the wiring ok, 240v at the terminals as its trying to start?

[chemi-cool]

First, check the compressor connections, make sure that start, run and common haven't been mixed.

Check the starting device [ starting relay or contactor], start capacitor.

The problem is in the electric power circuit.
Could the first compressor you have changed is still fine? Have it checked.

[dan281183]

I found out today that it was just warn but it was ok it is a csir. its a brand new relay and capacitor that came with the new compressor yes wiring is ok had a sparky at it 240v is going to the overload protecter then clicking on then off

[dan281183]

Checked them and they are ok found out first compressor is ok

[Brian_UK]

Double and treble check the wiring and components to the compressor. The sparky may not know what he was wiring up.

Follow the wiring instructions implicitly.

[mikeref]

I'd also check current draw to confirm wiring is correct. Test the capacitors... Mike.

[dan281183]

Done that went over wiring so many times still get same out come. I got told to try with out the thermostat overload protector but that just blows the fuse with out it.

[mikeref]

O.K, Go back to compressor windings and test resistance on both new ones. What happened to origional compressor? Strange that 2 new comp's are faulty. Check resistance is same as makers specifications.. Mike.

[dan281183]

I did that and they were ok i sent original compressor away and the compressor was ok. I could not believe it my boss phoned me today saying he had been called out for a job and he has exactly the same problem he tried a new relay and a capacitor still same problem.

[mikeref]

Something doesn't smell right here.. windings, voltage, current, caps and relay are good? new compressors are same rating as origional? I would reclaim refrigerant and leave a holding charge, then, with gauges on and minimal load now on compressor,.. Apply power and see if comp runs, well under the compressor rated current draw..Mike.

[dan281183]

Belive it or not i have tried that as well still no go i have been trying to figure this out for 2 weeks i just can't get my head round it like

[mikeref]

Belive it or not i have tried that as well still no go i have been trying to figure this out for 2 weeks i just can't get my head round it like
What i would do is to change brands. Source a compressor from another manufacturer. Two weeks without a freezer and customer will be pulling his hair out:eek:. The new comp's you fitted did have pressure in them when you pulled the bungs or opened the valves? Thinking no pressure in new compressors may have led to seized bearings or piston.

[dan281183]

He is bald now ha ha there has been pressure in them and when i have sent the compressor's back they have been fine inside and working ok on there tester.

[mikeref]

Compressors work on tester:confused:!! Something fishy about freezer site! Are you able to tap power from somewhere else there? Another circuit that say runs a coldroom. Sounds to me like voltage is being lost. Check for hardened/burnt wiring in your circuit and try something else, like an air compressor on freezer circuit and see if runs. Something of similar power consumption as freezer compressor...Mike.

[chemi-cool]

Another angel of view, maybe there is a voltage drop at starting the compressor, go to the source of electric connection and check ammeter what happened to the voltage when you start.

i am still sure its the power circuit and not control circuit.

[dan281183]

The voltage stays the same and it has around 38amps on inital start up

[monkey spanners]

Whats the make and model of compressor? Refrigerant type?

[chemi-cool]

The voltage stays the same and it has around 38amps on inital start up

This is not voltage! its the amp draw you are reading.

[Tradewinds]

If the compressor windings are good and its definitely wired up correctly. It shouldnt be seized because you have tried another compressor and you have confirmed the voltage is good.

So, what is happening on the neutral side of things? Have you got continuity all the way back to the neutral bar. If the neutral goes through a contactor, are the contacts making? Have you got voltage on your neutral? Could it be broken?

Just thinking outside the square.

[dan281183]

It's a L'unite caj2446z on R404a

[dan281183]

I have continuity all way back on the neutral side there is no contactor on the system doesn't seem to be any breaks

[chemi-cool]

your continuity must stop somewhere cause other wise the compressor would have been running.
What device starts the compressor relay then? A thermostat? A pressure control?
Check them for faulty contacts.

[monkey spanners]

I think i would wire it up off a plug, make sure the relay is mounted the correct way up or it will either not switch on or off at all or at the right time.
If it still didn't work i would be wondering if it is stalled due to a blockage in the discharge pipe, anywhere from the brazed connection near the bottom of the compressor to the condenser.

They are generally very good comps, the only time i had one that wouldn't start was when i had wired it up wrong.

If you put you amp meter on the start capacitor wire when its trying to start you should have current, if not the relay ain't working.

Do all the windings add up correctly?

http://www.youtube.com/watch?v=6IiIIMcAVGE

Its about half way through he shows how to measure the windings.

Jon :)

[dan281183]

There is no thermostat or pressure control in this set up when it is turned on thats it on constantly it goes on 5 15min hot gas defrosts it just keeps on running daft set up i think any way

[dan281183]

There don't seem to be a blockage there is still pressure after the condensor i have tried more than 1 relay and what not, there is power after the clickson/thermostat overload protector when i take the terminal ends of the compressor but soon as i put them back on it just clicks every 10 secs or so and if i dont have the thermostat protector on and conect it direct it just blows the fuse on the plug or some times the trip switch on main electric board.

[mikeref]

Is this freezer hard wired or plugged in with a lead to a power outlet?

[dan281183]

It is plugged in with a normal 13 amp plug

[mikeref]

Going back to post #15, have you tried to run anything with significant load value off this power outlet?

[dan281183]

No not yet but if it did work with some thing else why has it worked for so long before doing this now

[mikeref]

Good question, but for now we need to eliminate possibilities. You said that compressors removed from freezer work on test bench, therefore the comps are not the problem. Now we have to figure what is different between freezer location and test bench.

[dan281183]

yes this is true its just trying to figure out what has changed tho

[Brian_UK]

Dan(birthdate), I'm beginning to think that you are wasting our time.

It seems that everything that could be done has been done and yet it fails; either you or your electrician is doing something wrong and are not admitting it.

It's time to stop playing.

[dan281183]

Eh do u think i would be wasting my time doing this for a laugh I have came on this site to try get help i don't like to ask for help as i try my best to figure it out for myself but this has not been working for to long i have swallowed my pride and looked for help so don't tell me that i have made a mistake or playing games Brain UK or I wouldn't be on here now.

[arne22]

To possible options, I guess.

If two of the cables is mixed the motor and the compressor might rotate the reverse way. (For 3 fase systems by mixing two of the phaces og for single phase by mixing coil and capacitor.) I can see this option is mentioned above, and that it is possibly checked allready.

One other option: The Heat Pump contains an elecromagnetical checkvalve that does not open properly at the right time. This might trig a low press security switch or give a to jhight start current to the compressor electrical motor. (As it will see a blocked check valve.)

Just a suggestion ..

[dan281183]

arne 22 i don't fully understand what u mean about the elecromagnetical checkvalve could u explain more please

[arne22]

Some heat pumps has a electromagnetical valve that opens when the heat pump start. If it does not, it will start, and then stop after a short time of running.

Some heatpumps also makes the starts and stop this way. The thermostat does not control the compressor directely, by indirectely by operating the electromagnetical valve.

If the heat pump does not have such an electromagnetical valve at all, than this can not be the poblem. I would have a look, to see if there is such a valve, somwhere "along the lines". If there is, I would have checked if it works and if it got the electrical power at the proper time (to open.)

[arne22]

I think we has a decription of this "little thing" here (http://www.eng-tips.com/viewthread.cfm?qid=244227&page=1)

(but I thought the solonoid valve shoul be in the "not liquid line" .. ) (I'm not sure..)

[dan281183]

There is a solinoid valve but that is only used for the hot gas defrost

[Peter_1]

capillary blocked?

[Tradewinds]

Hi Dan,
This information is taken from the datasheet at http://www.cps-cool.de/PDF/CAJ2446Z.pdf. I would recommend checking that all components match these exact details. I note in particular that you mentioned CSIR above but datasheet say CSR. How many caps have you got?
Definitely check the following:
Compressor windings match what is listed below.
CSR or CSIR
Overload model number
Potential relay model number
Capacitor ratings
Are the caps wired up correctly and is the relay fitted to the correct terminals

Displacement : 26.2 cm³

Net weight : 23 Kg

Oil charge : 887 cm³

Oil type : P.O.E /

Expansion device : Capillary/Exp° valve

Cooling : Forced

Windings resistances at 20° C

Main Winding : 2.4 Ohms
Auxiliary Winding : 10.3 Ohms

Current

Rated current RLA : 3.8 A
Max current : 7.9 A
Start current LRA : 29 A

Electrical equipment : CSR
Overload : MST18AIN
Time check : 7.5s - 14s / 20.7 A
Opening temp.: 120° C
Closing temp. : 69° C
optional : T0750

Potential relay : RVA4O**
Pick up : 280/310V
Drop out : 60/121V
optional : 3ARR3*6AC*

Start capacitor : 88 μF / 330 V
Run capacitor : 15 μF / 400 V

Can you confirm that all of these details are exactly what you have onsite. If so, then it must be external to the compressor if compressor wiring and voltage is good.

[chemi-cool]

My last advise is: Strip down all electric cables and rewind the unit the you know it should be, using new cables.
If you are in no hurry, I will be in Scotland [east coast] in the beggining of June and can give you a hand....

[ptsac]

If the electrics are ok and the compressor runs on a test bench then you have to consider that something is preventing rotation. If the compressors are not seized then the suspicion would be a blockage on the discharge. Does this compressor have an oil cooler circuit pipe that has been mistaken for the discharge?
If you just run the compressor with suction and discharge open still using the same electrics does the compressor get away?
Can you post a photo.
just looked at tradewinds excellent info, no oil cooler.

[monkey spanners]

Worth checking to see its a caj and not a taj, friend of mine spent an afternoon trying to get a new comp to run before he realised it was a three phase one on a single phase unit.

[Tradewinds]

Good point Monkey Spanners.

I've had several 3 ph condensing units being delivered when they should have been 1ph. At some suppliers, the catalogue numbers are exactly the same for both types and its only the model number that is different.

Having said that a single phase comp will have 3 pins and the three phase should have 6 pins. The 3 phase probably wont come with a capacitor starter box either.

[monkey spanners]

Good point Monkey Spanners.

I've had several 3 ph condensing units being delivered when they should have been 1ph. At some suppliers, the catalogue numbers are exactly the same for both types and its only the model number that is different.

Having said that a single phase comp will have 3 pins and the three phase should have 6 pins. The 3 phase probably wont come with a capacitor starter box either.

I think the pins are the same on these, its only a 3/4hp hermetic, like you say it should come with electrics, but i have found with some equipment manufacturer supplied comps rather than wholesaler supplied ones that they package up the electrics seperatly so there is potential for mix ups, maybe they just get the spare from the production line?
Having said that the last replacement taj i fitted had another lecky box for three klixons, one per phase, but i think it was a bit bigger than this one thats giving problems here.

[arne22]

From the post 17 above: "The voltage stays the same and it has around 38amps on inital start up".

According to the data sheet from somewhere above, is't this a bit to much ?

Is it possible to measure pressure on the high pres and the low press side, while starting the system ?, to see if there is some restriction in the system, that gives a to high "high press" that in turn will also give a to high start current ..

[arne22]

Current

Rated current RLA : 3.8 A
Max current : 7.9 A
Start current LRA : 29 A

And these datas for the windings should be easy to check out with an ohm meter:

Windings resistances at 20° C

Main Winding : 2.4 Ohms
Auxiliary Winding : 10.3 Ohms

[Brian_UK]

Eh do u think i would be wasting my time doing this for a laugh I have came on this site to try get help i don't like to ask for help as i try my best to figure it out for myself but this has not been working for to long i have swallowed my pride and looked for help so don't tell me that i have made a mistake or playing games Brain UK or I wouldn't be on here now.
OK, we're just checking, thanks for your reply.

[1torr]

Hi Try running it with pipework disconnected.

[arne22]

Is it running now ? Was it any reasonable reason behind it all ?

[pie man]

Come on Dan did you solve the probem....?