Replacing low pressure control on refrigeration system

[harry]

I have a refrigeration unit that I have to replace the low pressure control.After calling a friend of mine who has the recovery unit I have used before and finding out it is at a brother-in-laws, about 80 miles away, on vacation for the next two weeks. Reading a previous post someone suggested sucking freon out of system with a jug in a bucket of ice water. Will this work? The compressor has service valves on both side so can valve off the rest of system. I need to recover all freon in compressor and replace it as it is a measured charge after the sight glass is clear[ has a receiver tank and flood valve]so it would be nice to not have to evacuate the entire system and start over. Will the ice water recovery work or should I find another recovery system? It is a R-22 system. Thanks

Russell HTLH 401 H22

[jumptrout51]

It is about 90% effective.

[Icehouse]

When replacing a low side component, preform a high side pump down.
HIGH SIDE PUMP DOWN

1. Turn power off.

2. Install gauge manifold as such. High side on Liquid Line Service Valve (King Valve) located on receiver.

3. Install Low Side on Suction Service Valve.

4. Place a jumper across control leads.

5. Crack both suction service and liquid service valves off of back seat position.

6. Turn Power Back on.

7. Slowly front seat liquid line service valve while observing low side gauge. Do not let it go below 2 psig.

8. When low side gauge reads 2 psig, turn off power and front seat suction service valve quickly.

You have now isolated the system charge in the receiver and can now remove the low pressure control with out the loss of refrigerant, nor the need for a recovery machine.

9. Replace the low pressure control and replace the drier. (Anytime you open a system, replace the drier).

10. With the power off, gently reverse the procedure.

Now you are done.

[JWWebster]

If using the bucket and ice method just watch the low side gauge. When it is close to zero you have done it. You may now proceed to change the switch.

[Icehouse]

If using the bucket and ice method just watch the low side gauge. When it is close to zero you have done it. You may now proceed to change the switch.

If he follows what I have outlined, there is no need for an "ice bath". Been using the method over forty years, but then again I don't know that much.   

[JWWebster]

Let me get this straight. While the unit is running, I shut off the high side valve. I let the compressor capture the freon, I watch my guage to zero pressure or near it, and then I close the low side valve,and shut down the outside unit?

[Icehouse]

JW, he is replacing the control on a "Refrigeration Unit", that's why the mention of receiver and sight glass. No not in the compressor, rather the receiver although you can apply this to A/C as well isolating the charge in the condenser. 

[Icehouse]

JW, he is replacing the control on a "Refrigeration Unit", that's why the mention of receiver and sight glass. No not in the compressor, rather the receiver although you can apply this to A/C as well isolating the charge in the condenser. Also not closing the high side, rather the "liquid line service valve".

[Icehouse]

See attached. 

[JWWebster]

Whichever method you use you want minimize the loss of freon into the atmosphere. Since the unit is an R22 unit you allowed a small amount of freon loss. A pound or less I believe it is.

[harry]

Thanks for the help Icehouse. I cant get your  attachment to open so I guess that can my next challenge. The refrigeration unit now shuts off like it is supposed to with it's new low pressure cut out.

[Icehouse]