Pressure Switch

[printcom]

This one is a bit off the beaten track but I have learned that there are a few clever devils on here who might be able to help with my latest head scratcher.
I picked this Air Con service station up cheap last year and was told that there was a problem with the vacuum pump. I have tested the pump and all works well, the problem seems to be the pressure switch fitted on the vacuum side - the sparse info I have says it is incorrectly calibrated or faulty.
Does anyone know how to:
1 Test these things
2 What the initial settings should be ( the lid was loose)
3 Where I can buy a replacement from, it appears the it is a Ranco 016-052 but I cant find where to buy one from.

 

[brightspark]

https://www.google.co.uk/#q=ranco+pressure+switches&spell=1

 

[Tigman]

 

[daleyd]

https://www.google.co.uk/#q=ranco pressure switches&spell=1

I looked at the name and thought I'd never heard of ranco. Then I looked at your google search. Then I realised I actually work for invensys (the parent company that owns ranco). Oops

 

[the snooper]

a simple test would be a continuity test if the unit doesnt power up, looking at the settings they are very low, cut out is set at 10psi and back in when the pressure drops a couple of psi

 

[eil]

To set them up correctly its done by attaching the switch to your nitrogen cylinder and noting the pressure that it cuts in and out on your pressure gauge, the blue one in your pic would be best, the settings shown on the switch is just a rough guide to get you near. I take it that the switch controls the gas recovery side of the unit and not the vacuum pump itself.

 

[the snooper]

im not sure it will work correctly without being connected to anything you will need to look it up, the auto units recover the gas then go onto vacuum the system it would be worth finding someone with the same system and get advice on it

 

[printcom]

Sorry chaps that last post got cut short, her indoors was ragging my ****. Thanks for the tip brightspark - id have never thought of that. I managed to have a look at it last night when the heat from her who shall be obeyed had dissipated a bit and found that the pressure switch is connected to the back of the solenoid on the recovery line and is pressurised with gas. Setting the cut out to 4 bar works and the vacuum pump runs fine although I haven't got a clue what pressure to set the cut in to. I also haven't got a clue why it needs 4 bar pressure to operate a vacuum pump, more research needed I think. I might have to ask brightspark for another link
Thanks for all your help chaps.

 

[eil]

If you put 4 Bar on to the vac pump it will blow all the oil out of it, are you sure you are not talking about the recovery compressor.

 

[the snooper]

If you put 4 Bar on to the vac pump it will blow all the oil out of it, are you sure you are not talking about the recovery compressor.

it has to be for the compressor as it is a pressure switch, not vacuum, its measured in psi, if it was vacuum it would be measured in hg or similar

 

[eil]

it has to be for the compressor as it is a pressure switch, not vacuum, its measured in psi, if it was vacuum it would be measured in hg or similar

Yes, of course Snoop, how come your allways right sometimes

 

[the snooper]

Yes, of course Snoop, how come your allways right sometimes

ill have you know im always right apart from when im wrong

 

[printcom]

If you put 4 Bar on to the vac pump it will blow all the oil out of it, are you sure you are not talking about the recovery compressor.

Looks like eli's right, I spent all day on it yesterday and managed to successfully recharge my van but in doing so I had to play about with the settings a bit. The instructions helped a lot when it stated that the recover function cuts out when the pressure drops below 0.8 bar and cuts back in at over 1.1 bar. It appears that the circuit has to be open vacuum pump to work which means that there is no more refrigerant to recover. It all makes sense now
Mind you it didn't all go to plan, I recharged my telehandler only to find that the compressor is knackered, should have checked it first - its seized solid I only checked for power to the clutch. The only identification I can find on the compressor is Diavia NS 8, I have had a good look via google (before brightspark send me a link) and cant find anything that matches to the NS 8, I do hope I don't have to go to Merlo as it will probably bankrupt me.