Fridge Help

[airconadam]

hi guys not sure if this post is in the correct area for starters but all it is ihave been asked to look at some fridge units well they are bottle coolers now ihave worked on fridges before but not alot and just looking for some more info really, do i just check the pressure etc to see if it running correctly but also the fridges ihave worked on never have stubbs on now i take it this is because you shouldnt really be touching the system is that right? again the ones ihave worked on ihave had to put thos screw stubbs on but find them not the best is that the only way really of geting into the system or are the other things out ther? basically ijust want to know things to check is it just like when i go to an ac unit etc thanks alot.

adam

[Gary]

Far too many service techs go straight to the pressures. This is NOT the best way to check out a system.

Is the temperature control calling for cooling?
Is the evaporator getting good airflow (coil clean and fan working properly)?
Is the condenser getting good airflow (coil clean and fan working properly)?
Is the compressor running?
Now check the evaporator delta-T (air on temp minus air off temp).
If the delta-T (dT) is right (given proper airflow across both coils), then what's not to love?
Now make sure the temp control shuts off when it is supposed to.

And leave your gauges in your tool box (unless/until the dT says you have a refrigerant flow problem).

And yes... this is the same way you should check out an A/C unit.

[Brian_UK]

Relocated this from Air Conditioning section.

[monkey spanners]

The thing i find with small stuff is that it takes ages to start doing something after turning on (even when working properly), what i mean is i turn it on, 30 seconds later look at the thermometer and think, its not working. So i find a bit of patients is called for.
Also i have found that a frozen up evaporator will cause the suction pressure to drop very low and look like it is short when it isn't.

Jon

[Andy AC]

Some bottle coolers (Gamko) have defrost timers, so if you find the condenser fan running and the compressor not, look for a timeclock before ripping the electrics cover off the comp and getting your tester out - its not always that easy to get at.
Also Cornelius bottle coolers have a metal mesh filter which slides out from the front air intake - a lot of people don't know that they are there.

Andy

[Gary]

Also i have found that a frozen up evaporator will cause the suction pressure to drop very low and look like it is short when it isn't.

Jon

Exactly so. You can't tell if you have a refrigerant flow problem until you have eliminated any and all airflow problems. Those who start with pressures are doing things the hard way. Airflow is crucial.

[Gary]

Also Cornelius bottle coolers have a metal mesh filter which slides out from the front air intake - a lot of people don't know that they are there.

Andy

High delta-T across either coil is an indicator of airflow problems.

Over the years I have encountered many systems whose coils appeared to be clean yet the dT was high. The problems? Wrong fan blade, blade installed upside down, fan running backwards, split coil with dirt hidden in the center, hidden filters, undersized ductwork. The list goes on and on...

Low evap dT indicates refrigerant flow problems.

dT is a key indicator.

[airconadam]

excellent fellas something to get my teeth into,iknow what you mean by not chekcing pressures first do the easy stuff first then start playing thanks alot for all your help will prob be posting back in afew days when i have been to the fridges hehe another thing when you say take the air on and off on the evap with they not be both the same or very close as it is close and small if you know what i mean eg air con units air off can be 7 but then air on is 22 because the room is hot but in a fridge its all close and small thanks alot

adam