main board

Hi 

If your willing to ship the unit to us we can reapir it. But i would pull the back off and check to see it the fan is working. We sell replacements if you need a fan.

Does the tec 4 have a fan to cool the heat sink from the peltier element?  We replaced the peltier and it still wont cool!  Help!  Thank you!

edit... I just noticed my search took me to a tec 5 instead of a tec 4.  Still, any help?

The Peltier element cannot work correctly if there is no fan or special cooling on one side. First, is there power to the Peltier element, usually 12 volts? If there is, it should cool + heat up from different sides. If there is no 12 volts, it can be taken from the main power supply temporarily or permanently. Usually, the Peltier element and the fan for its cooling are connected to the same wire. If the fan does not rotate but there is power, we change the fan.

It's been awhile since I've opened up a TEC 4. However, on the TEC 5, the fan is in the rear, by the main circuit board. The fan draws air from the front, across the Peltier heat sink, to the rear, and then blows air up across the main circuit board. The TEC 4 may do something similar. Other embedding centers have a fan mounted to the underside of the Peltier.
As others have said, there must be air flow across the Peltier heat sink for it to cool for more than a few minutes. If it is cool for a few minutes, after being turning on, but then fails to stay cool, it may be an indication of a failed fan or clogged fins (in the heat sink).

I can't find a fan anywhere.  I don't know how this thing ever dissipated the heat.

The specs on the cold spot may only be to cool down to +10 or +15C, so it might only get cool, not cold.
IIRC, the Peltier in that unit has fins that extend to either edge of the instrument. They have to be clean, and the grills must be open for maximum heat exchange. And the instrument should be sitting on feet (or bumpers), to allow air flow from below (no towels underneath it). There must be good thermal contact on the upper and lower surfaces of the Peltier (heat sink compound can dry out and leave voids, over time). Ambient air temperature in the lab will also be a factor, especially if there is no forced air cooling in the TEC 4. Also, don't set the hot surfaces near it hotter than necessary. And, of course, check the DC voltage (and DC current flow) to the Peltier.

I'll keep messing with it.  Thank you for your input!