Tue Oct 03 2017

Cooling issue

I have an 1850 that has been working properly and maintaining a temperature of -22C. The unit suddenly stopped cooling properly, the chamber will not get below 6C. I removed the trays inside the chamber and the base of the chamber is noticeably cooler, and the side panels just below the glass door are very warm to the touch. What could be causing this issue?

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Tue Oct 03 2017Reply from Paul_8779
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It's most likely a problem with the fan that cools the condenser.  They quit all the time and cause just the behavior you describe.


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Wed Oct 04 2017Reply from Steve1980
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The condenser fan is a good place to start. Cm1850s also have problems with their expansion valve system frequently. A good way to tell is to unwrap the black insulation above the expansion valve. shit the machine down for a few minutes and fire it up with the two lines exposed. They should frost up lightly at first. Keep watching they will thaw and if one frosts up significantly more than the other after a few minutes you likely need a new expansion valve module. It is located inside the back panel on the left side a few inches below the chamber the module itself is the silver boxy looking part. it's the two lines above that you would have to uncover. Be sure to reinsulate them after testing the unit.

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Fri Oct 13 2017Reply from phung gia
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Same me . problem is expansion valve.

you can remove the Armaflex insulation from the output of the E-valve module and You turn on 15 minutes and touch the two outlets of the expansion valve you will see a line very cold and a line not cold

 


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Fri Oct 13 2017Reply from Steve1980
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It is most likely the Expansion valve module.  You can purchase it from Leica in a kit that comes with the E-valve and a filter dryer.  it will take a good hvac person to install as it rather complicated for the average tech.  a good test is to remove the back panel...and above the silver insulated box to the left of the electrical slide out is the expansion valve module.  Remove the insulation from the two pipes above it.  shit the unit down for a few minutes and watch them frost up. they maybfrost and thaw once or so but if one frosts more than the the after the first frost/thaw cycle it's a bad e-valve.  it's about$1000 kit but well worth it.  what is probably happening is the wall evaporator under the microtome is cooling but likely the gilles evaporator on the top is not cooling.  so feel by the base of the microtome and then feel the gilles evaporator when you do the frost test and see if both are cold or only the walled evaporator under the microtome base.


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Thu Oct 14 2021Reply from Ross
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Does anyone know if the CM1520 uses the same expansion valve module as the CM1850?


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Fri Oct 15 2021Reply from Ross
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The e-module kit part number, as listed in the service manual, has been discontinued. Leica customer service says there is no replacement. Does anyone know a good part number?


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