paragon defrost clock walk in freezer problem

[SandShark]

How badly were the coils iced up. Was the ice uniform and covering all the coil or was the ice covering one or two particular areas of the coils? I ask because, if there are issues with the refrigeration part of the system (low charge, superheat issues, etc.), excessive ice can build up in the areas closest to the expansion valve rather than uniformly across the evaporator. When this happens, since the defrost termination Klixon is located on the opposite end of the coils, the ice nearest the expansion valve will not thaw and, eventually, will keep building up over time.

Once you defrosted the coils and you put it back into defrost, it is normal for the defrost to terminate before the time clock terminates the defrost. As mentioned, that's what defrost termination is supposed to do.

[2sac]

...and by adding hot water to the equasion you were unable to determine if the defrost termination switch is bad. If the switch is shorted out, it may have let the magic smoke out of the solenoid on the clock.

[K_Neil]

Disconnect X on the timer for a temporary check of defrost sequence, heaters etc. Is it only defrost termination at the klixon or fan delay too?

[hvac wiz 79]

I stick the small bead from my k type thermocouple right under the termination switch & ensure its secure. I then cycle into defrost & look at the temp. I watch a few cycles. All this mention of defrost termination is great but you also need to check the heater limit. Do it the same way i mention above. Ohm it out cold & warm also. I'm to the point i change these as a set now when one is bad

[bunny]

I've seen the defrost timer pins so worn that they no longer initiate a defrost cycle. Easy thing to check and confirm or deny it as a problem.

The bottom of the pin should be round.

[frigeguy]

working on a walk-in freezer with a heatcraft evap, both coils are iced up found the clock set to noon, its 6 oclock threw it into defrost manually, tested electric heaters all working fans turn off the way they should deiced coils completely with the help with using hot water to speed process up. Defrost clock set to 40 min defrost, but would come out of defrost before then before the 40 minutes. time clock motor is working and moving ahead, so trying to figure if it is was the clock got stuck or could the defrost termination kilxon be no good and throwing it out of defrost to soon.

The time on a clock is not a sign of trouble to start with, a power failure or a service tech testing the defrost would explain the incorrect time. As I read it you put it in a defrost and then you proved termination was working with hot water. No problems there...

[VTP99]

i had 120v on x when it was out of defrost

If it's a 120 volt clock you will have 120 there at X. It is passing thru the coil all the time. The wire attached to X is what provides neutral to that coil.

[2sac]

If it's a 120 volt clock you will have 120 there at X. It is passing thru the coil all the time. The wire attached to X is what provides neutral to that coil.

Depends on the clock configuration. An 8145 is configured with X energizes the termination solenoid. The 8045 doesnt have a solenoid and X is neutral

[VTP99]

Depends on the clock configuration. An 8145 is configured with X energizes the termination solenoid. The 8045 doesnt have a solenoid and X is neutral

Yes this is true but i thought we were talking about a clock with a solenoid. Good point maybe he doesn't have a solenoid. What's he doing with a termination then ?

[badgerland01]

First thing you should do when you find an iced up evap coil is mark the time clock to ensure it is spinning. I have seen them stick and then when manually turned they work for a few days again. Not saying this is your issue here, but it will be one day.

[socotech]

First thing you should do when you find an iced up evap coil is mark the time clock to ensure it is spinning. I have seen them stick and then when manually turned they work for a few days again. Not saying this is your issue here, but it will be one day.

I too have seen this several times. I'd bet you got a bad clock.

[markettech]

working on a walk-in freezer with a heatcraft evap, both coils are iced up found the clock set to noon, its 6 oclock threw it into defrost manually, tested electric heaters all working fans turn off the way they should deiced coils completely with the help with using hot water to speed process up. Defrost clock set to 40 min defrost, but would come out of defrost before then before the 40 minutes. time clock motor is working and moving ahead, so trying to figure if it is was the clock got stuck or could the defrost termination kilxon be no good and throwing it out of defrost to soon.

As has been mentioned earlier, it seems you went ahead and took care of the issue without making a determination as to the cause.

If you defrosted the coil with hot water and then ran it into defrost to check the overall operation - the termination klixon should kick the system out of defrost before the 40 minute failsafe (after all, the coil is completely clear, right?).

At this point, if it were me, I'd make it a priority to stop back in the next few days to check the coil condition, defrost set pin condition, and verify whether or not the termination klixon is operating properly after a few days of run time under its belt.

[BDOLIN]

Although we are all very comfortable with mechanical timeclocks, with the progress in electronics and the level of control and flexibility they offer, I think the days of mechanical defrost clocks are numbered, no pun intended.
Think of the improvements in settting, efficiency and power electronic fuel injection has over mechanical carburetors.