Walk In Freezers

HEATED AIR VENT

The reason for these is when the door is closed to the GWIF is the air inside will vent to the outside or for pressure relief,the reason its heated is to prevent the moisture in the air being vented from freezing thus blocking the vent.

STRIP CURTAINS

Strip curtains are very important to have inside a GWIF, they create a barrier to prevent an inrush of air when the door is left open for a sustained period of time, thus preventing moisture from entering and building up ice inside the freezer.

ICE BUILDUP ON SUCTION LINE

What you see here is another example of both air intrusion and an improperly insulated suction line.

AIR INTRUSION

What you see here is a sign of whats called intrusion meaning outside air is coming in through the wall seams, ceiling joints, usually in close proximity to where there is an air gap.

HEATED AIR VENT

The reason for these is when the door is closed to the GWIF is the air inside will vent to the outside or for pressure relief,the reason its heated is to prevent the moisture in the air being vented from freezing thus blocking the vent.

FAN SWITCH

The reason for a door/fan switch is to shut fans off in a freezer whenever the door is open thus preventing moisture from entering at a rapid pace causing the coils to freeze up.

STRIP CURTAINS

Strip curtains are very important to have inside a GWIF, they create a barrier to prevent an inrush of air when the door is left open for a sustained period of time, thus preventing moisture from entering and building up ice inside the freezer.

THREE WIRE KLIXON

This is a 3 wire klixon generally used on walk in freezer evaporator coils.

ICE BUILDUP ON SUCTION LINE

What you see here is another example of both air intrusion and an improperly insulated suction line.

WALK IN FREEZERS

In this section I will talk about walk in freezers, and the issues associated with them.

So the basics, a walk in freezer is just as the name applies, it is to keep extra food frozen so when the sales floor freezer inventory is low product can be pulled from the walk in freezer, also serves as bulk storage of what will not fit in the reach in freezers on the sales floor.

Now  I will talk about common service call issues:

AIR INTRUSION: This occurs when the freezer door is left open for too long with no strip curtains, panel seams that are not tight are the two most common causes of Ice build up on the inside walls this happens because warm air is meeting cold air, so thus causing the warm air to condense and freeze on the walls, as you can see in the above picture examples this is the end result.

There are numerous ways to fix this issue, but always will involve the freezer having to shut down and thawed out for at least 48 hours which customers tend to not wanna do, but if the do decide to do so you as the technician can do the following:

1) Put sheet metal over the seams, if you decide to go this route use a piece of thin gauge sheet metal 6″ wide by 6′ long, bend it in half, then on each side (long side) go back 1.5″ and fold it INWARD 15 degrees, then use a BUTYL  to seal the seams of the box, then run a bead of butyl on the sheet metal itself, then use Phillips head self taper tek screws to fasten the sheet metal to the box seams, now is for the corners of the box, for the vertical seams use a straight piece of thin sheet metal, put a 15 degree bend inward, fill the box seams with butyl, put a bead of butyl on the sheet metal as well and screw it to the wall, this method I have described is a permanent fix to any air intrusion coming from the seams of the box. Another method to help as well is to install strip curtains, these are installed on the inside of the freezer, on the inside door way, the keep air from rushing in when the door is open.

ICE IN FRONT OF COILS: This is primarily caused by the fans coming on to quickly after defrost, so what happens is after the coil is done defrosting either hot gas or electric, there should be 5-7 minutes of drip time before the refrigeration comes back on, then the coil should get to 20 degrees before the fans come on, if not the fans will sling water to the ceiling in front of the coils, and the ice will build up over time.

To fix the above said problem of fans coming on to quickly check the following:

1) If the system is on the EMS check to see there is a minimum drip time.

2) if on a mechanical defrost termination/fan delay switch check to make sure the temperature is set to 20 degrees before the fans energize, if not adjust it accordingly and or the switch may have to be replaced, however it may also be on a KLIXON if so it may have to be replaced, be sure to use your meter to check the KLIXON, trace the wiring out, determine what wires go where and the fan delay  should be open if its not at 20 degrees RED = COMMON..BROWN= Defrost termination BLACK= Fan delay.

DEFROST TERMINATION: This also can be a big issue inside freezers, if the termination temperature is too high, then moisture will condensate on the ceiling,drip onto the floor, freeze and cause a slip and fall situation for the customer. If the termination temperature is too low then the coil will no deice properly, eventually leading the coil freezing like an ice block. Now the industry standard is 48 degrees for temperature of defrost to terminate.

BULLET POINTS:

1) Where is air intrusion coming from?

2) Fan delay..20 degrees before fans should come on.

3) Termination of defrost..  48 degrees (coil temp)

4) Proper drip time after defrost before refrigeration comes on.

5) Strip curtains are very important to have.

6) Is the door gasket in good shape? or missing/damaged?

7) Door frame heater working? 

8) Most walk in freezers should have defrost set for 3@30-40 minutes for ELECTRIC defrost..If its HOT GAS then 3@15-18 minutes, now these numbers can change based on traffic, strip curtains , heavy usage and so on.

TROUBLESHOOTING FREEZERS MECHANICAL/ELECTRICAL

Within this section I am gonna talk about diagnosing freezer issues such as not cold enough, too cold, not working, coils iced up solid.

FREEZER NOT COLD/WARM:

As written about in the previous chapters of this website, the same exact principals apply here, if you get a call that the freezer is warm there are numerous things to check, the easiest is, is the door closed so the fans can run? check the rack/compressors in the motor room or if its a an RTU check out the unit, is the compressor running? is it low on refrigerant? and so forth. Numerous other things to check is the TXV feeding properly? are the fans running? if not be sure to check the KLIXON to make sure it closed, if not then you may have to jump it out for time being, check the breaker, if need be pump down the coils and check the TXV screen to make sure it is clean, check super heat, check the power head on the TXV.

COIL/COILS ICED UP SOLID:

This is generally a sign the derost heaters or hot gas valve is NOT working, the very first thing to do is to deice the coil with hot water. First get a big trash can and fill it with hot water, use a sump pump and hose to deice coils/coils, or if there happens to be a hot water hose bib near by that may be an option as well, after all that get the pan cleared of ice exactly where the drain line is, meaning get the drain line opened up first inside the drain pan, then proceed to deice from there, more often than not you will have to remove the front fan guards and deice from the front of the coil as well as the back side of the coil as well, now once the coils are 100% cleared of ALL ICE, put system into defrost, whether its a time clock, or EMS controlled, put system into defrost, make sure the defrost contactor pulls in by measuring the amp draw on the LOAD side of contactor, if not check the breaker, check the control voltage of the contactor, if the contactor pulls in but no amp draw, then take it OUT of defrost, go to the coil and check ALL heater connections its possible you may find a burnt connection repair if that’s  the case and then put system back into defrost, if you have an amp draw, then go to the coil and check amp draw of heaters at the coils. Also what else tends to happen if the fans are not running check the wire connections, some of the fan motors have plugs that tend to burn up, become unplugged, get chopped up by the fan blade because the wiring is too close to the fan blade. Also when checking the defrost contactor they tend to located it whats called an “RDP” panel, which means Remote Defrost panel, its a separate panel only for defrost contactors, Tyler was famous for doing this. REMEMBER: All the same basics of refrigeration apply here when checking out refrigeration issues in walk in freezers as described on previous pages of this site.

ANOTHER WALK IN COOLER COIL

Another example of a dirty coil.Same situation here as to left side picture.

DIAL THERMOMETER

This little gem has been responsible for more bogus service calls than you can imagine, upon receiving a service call for a warm cooler/case ALWAYS immediately upon arrival check the temperature with your thermo-couple (FLUKE OR FIELDPIECE) DO NOT RELY on this type of thermometer. NOTE: This item can be made to read proper temperature, first remove the clear plastic cover use a small screwdriver and turn it CLOCKWISE to read lower or COUNTER CLOCKWISE to read higher.

MULTI DECK MEAT CASE

This another picture of a multi deck meat case in defrost. The evidence is the how the mirrors are fogged up, now this isn’t always the case this can also be indicative of airflow issues with the case.

WALK IN COOLER COIL

What you see here is a coil that is plugged with debris, thus causing airflow issues.

Heres why this happens: The most popular places to find this issue is inside deli walk in, dairy walk-in and produce walk-in coolers, and this is caused by boxes being torn or broken down inside the cooler and as that is being done micro fibers escape from the boxes, and end up in the coil, now by the time you see this issue, the coil is already packed full of debris because the coils PULL air through , the debris backs up and evenyually shows itself on the outsideof the coil.

ANOTHER WALK IN COOLER COIL

Another example of a dirty coil.Same situation here as to left side picture.

LOW PROFILE COIL

These particular coils tend to be used in meat prep rooms, walk in coolers and many other medium temp applications.

DIAL THERMOMETER

This little gem has been responsible for more bogus service calls than you can imagine, upon receiving a service call for a warm cooler/case ALWAYS immediately upon arrival check the temperature with your thermo-couple (FLUKE OR FIELDPIECE) DO NOT RELY on this type of thermometer. NOTE: This item can be made to read proper temperature, first remove the clear plastic cover use a small screwdriver and turn it CLOCKWISE to read lower or COUNTER CLOCKWISE to read higher.

MULTI DECK MEAT CASE

What you are seeing here is a multi deck meat case in defrost, and how you can tell is that any multi deck meat case that has mirrors like this one does will fog up up in the defrost cycle.

MULTI DECK MEAT CASE

This another picture of a multi deck meat case in defrost. The evidence is the how the mirrors are fogged up, now this isn’t always the case this can also be indicative of airflow issues with the case.

MEAT WALK IN COOLERS

Meat walk in coolers tend to be the coldest of any of the walk in coolers in grocery stores,by virtue of the product loaded into them.

Now meat walk in coolers will have either hot gas or electric defrost because the coil runs much colder than say the produce,dairy walk ins, so troubleshooting them will be the same as troubleshooting a walk in freezer coil

check to see if the heaters come on in defrost, or is the hot gas line solenoid is energizing in defrost. Also the drain lines in the meat walk in MUST be insulated just like a freezer and have a heater line run INSIDE of the insulation to further keep the drain line from freezing.

PRODUCE & DAIRY WALK IN COOLERS

PRODUCE/DAIRY walk in coolers are fairly basic, the boxes tend to run an average of 35-37 whereas DAIRY walk in coolers tend to run at 34-36 degrees have off cycle defrost, when troubleshooting them the basics still apply is the txv feeding? fans running? solid sight glass on the rack?

Now another common problem with walk in coolers is the drain pan tends to get clogged up with debris this is caused by the tearing apart constantly of cardboard boxes and it produces micro fibers and those micro fibers end up in the coil and eventually clog the drain hole in the pan, to clear the drain use C02 or nitrogen and you can find where the drain ends up at and blow the line from that direction, sometimes you will have to take apart the union and clear the drain both directions, after the drain is clear it is advisable to run copious amounts of hot water down the drain via pouring it into the drain pan to flush out any remaining debris/garbage.

HOW TO PROPERLY CLEAN COILS

Now cleaning coils is actually an art.

Lets start with some basics, first of all as seen in the above pictures of “Dirty coils” once you see dirt/dust on the outside of the coil the same stuff (dirt/debris) is already inside the coil the reason for this is the fans PULL air from the backside of coil, heat is removed and cold air is BLOWN out the front of the coil so that’s how debris gets built up inside the coil.

To properly clean a walk in coil:

1) Turn refrigeration and fans OFF

2) Brush the dirt/debris off of BACK of coil if its really caked on.

3)Use a foam cleaner, how this works is by foaming, it will push the dirt/debris OUT then use a hose to wash foam and dirt out. Of course what Im talking about applies to the BACK of the coil.

4) Remove fan guards, clean them and clean coil from the FRONT as well.

5) Once you think you are done shine your flashlight from either the back or front of coil you SHOULD see light through the coil, if not keep cleaning/washing/rinsing coil till you can see light through it.

6)Put fan guards back on, turn fans on let run for 15 minutes THEN turn on the refrigeration.