LI-610 Dew Point Generator Cannot Reach Below Ambient Temperatures

Occasionally, LI-610 Dew Point Generator Users will not be able to achieve a temperature set-point below ambient temperatures. This can be caused by a combination of issues.

1. The Radiator and/or the Condenser Reservoir are low or empty.
2. Coolant pump is not on or is not working.
3. Blockages have formed in the cooling water path.
4. Peltier coolers are not receiving proper voltage.

Please see the following pictures and labels for descriptions on troubleshooting these issues:

The Radiator and/or the Condenser Reservoir are Low or Empty

1. Make sure the Radiator is full (pg 2-1 in Manual). Only use distilled or deionized water (approximately 200 ml total). Add 15-20 drops (2 ml) of algicide. Fill until water level is visible in the tube.
2. 
2. Make sure Condenser is full (pg 2-3 in Manual). Only use distilled water (approximately 20-25 ml total), and make sure the water level in the Condenser Reservoir is between Max and Min. Replace cap plug and start LI-610. Watch level to see if more water needs to be added.
3.  

Coolant pump is not on or is not working

Check to make sure that the coolant pump is working properly. Disconnect the "To Cooler" tubing on the backside of the LI-610. Have the “COOLER” switch on the front panel set to OFF. Power ON the LI-610 and briefly toggle the "COOLER" switch to the ON position. If the pump is working properly, water will discharge from the "To Cooler" port. If water does not discharge, contact LI-COR.

Blockages have formed in the cooling water path

1. Check for a blockage in the cooling water path. (See the following pictures for an example of this blockage.) Without coolant circulating through the Peltier coolers to remove heat, they cannot achieve a temperature target below ambient. There are two Peltier coolers, one on each side of the condenser block. There are water lines that connect the two coolers, and also run to and from the radiator. A blockage can occur in any of the hose fittings that connect to the Peltier coolers. To remove the blockage, disconnect either the "From Cooler" or "To Cooler" hoses from the back of the LI-610.Use the syringe supplied with the LI-610 and seal it to the hose fitting as best you can. Then use the syringe to push and pull water through the system until the water flows freely. This should dislodge any blockage that might inhibit coolant circulation. If a blockage is detected, flush it out of the lines with water. The precipitates that cause these blockages are generally formed during storage by a reaction between water, air, and the brass hose fittings. These precipitates can be prevented by keeping the radiator reservoir full of de-ionized water during storage (if stored in temperatures above freezing).
2. Reactions between water, air, and brass can build up precipitates and cause blockages. Keeping the Reservoir full can help prevent this. These blockages can happen at several tube connectors (hose barbs) located on the condenser. Inserting a thin, flexible (but firm) wire can sometimes break through the blockages and loosen the precipitates. These can be flushed out afterwards with the syringe.

Peltier coolers are not receiving proper voltage

If the above measures do not solve the problem, the Peltier coolers may not be powered properly. Contact LI-COR for servicing this problem. If none of the above suggestions allow for the LI-610 Dew Point Generator to reach be Temperatures below Ambient Temperatures, contact LI-COR for servicing the LI-610.