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subzero*psia
23-03-2001, 09:11 PM
Okay lets hear about the one that nobody else could fix and then you came along. Almost like magic the problem went away and your boss was soooo impressed he tossed around the idea of doubled your wages... ;)

Brian_UK
06-04-2001, 11:24 PM
Not quite due for a raise yet I think....

Well I made a right pigs ear of what should have been a simple job yesterday.

Called to Sadia freezer that wasn't reaching temperature; checked the obvious, were the compressor and fans running, yes, so far so good.

Checked the door switch for the evap fan as we've had a lot of failures just recently and the eveporator was looking well frosted over half of the coil. No, the switch was wriggled, switched, poked and prodded but seemed OK.

Next stage, check the operating suction pressure, no high side access port. First mistake, assumed that the label on the compressor was correct but not thinking straight accepted what it said as R134a. The pressure didn't tie up with the evap temperature shown on the controller display and the suction temperature showed a high superheat.

So, I started a defrost cycle to get back to a clear coil and rechecked the readings, still didn't make total sense but the indications were a slight gas shortage. Added a few grams (ozs) of R134a and the readings still didn't make sense.

The light bulb flashed above me as I had been thinking it was strange that we should be using R134a on a -20C freezer, but, hey I'm only a simple guy.

Stopped what I was doing and managed to drag the freezer away from the wall and found a poorly written label that said that the refrigerant was 69S (R403a) - now the stupid readings made sense!

Anyway, get the reclaim unit out of the van, pull the 403a/134a mix out and pull a good vacuum on it. As we didn't have any 403a in store or at our nearest supplier the decision was to go for R404a which would have been my preferred gas for that temperature anyway.

Restart the thing and trim up the gas charge, still getting funny evap temperatures, far too cold; do a visual on the evaporator and find the bloody fan isn't running. Yep, you've guessed it, the door switch had gone faulty and probably had been all along.

Moral, stand back and don't take your first thought, think about it.

Brian

subzero*psia
07-04-2001, 04:46 AM
Well I can out do that one...

Just this week I got a call that a walkin freezer was getting hot. They had another servicer in and he fixed some wiring that had gotten pinched. (He did a good job too.) This place is wired really weird... wires are marked with multiple colors of tape etc.

Anyway, I figured maybe it was the defrost terminator or the clock. Sure enough it was the clock. I put in another brand and was wiring it up. For some stupid reason I wired the second leg to the N terminal... thinking about the neutral I guess. Still I didn't catch it (this is a 230 volt system)... I turned the breaker on... POP! DUHHH!!! :eek:

Luckily I didn't need a third switch for this unit and removed it from the assembly (the contacts between those terminals were fused solid as you might have guessed). I rewired ran the second leg to the X terminal as I should have in the first place... watched the unit go through a defrost and back into cooling etc. The unit is running fine but I sure made a really stupid mistake...

monkey spanners
30-10-2010, 07:38 PM
im new and not sure what to do

Maybe you're a poet who doesn't know it!