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How to Replace a Temperature Controller on a True Freezer Model t-49f

It’s fair to say its temperature controller on a True freezer model T-49f HC reach-in freezer works hard. When it quits working, you may see a p1 error code. Of the variety of electronic controllers used across their model lines, only the Dixell electronic temperature controller issues a p1 alarm. It means there is a thermostat probe failure. 

There are three relay retrofit kits available to fix the problem. To ensure you are ordering the correct replacement part, use True’s Serial Number Lookup on the True website: True Manufacturing | Support | Serial Number Lookup. The site will give all the relevant information on your particular model.  

Replacement part numbers have changed in the past several years, so check the date plate inside the cabinet. Specifically, for models manufactured after March 9, 2008, the temperature control model number may be listed as #800345. It has been replaced by True 988271 TEMP CONTROL KIT 077B1264 | Parts Town. Likewise, part #800369 has been replaced by the True 988266 TEMP CONTROL KIT 077B1212 | Parts Town 

The company has detailed replacement instructions in its resource library, under “Temperature Controls, Thermometers and Timers,” recapped here.  

To replace the temperature probe on a T model freezer with 1/3 horsepower motor, disconnect the power. Remove the lower grill by loosening the upper screw on each end of the grill and completely removing the lower screws. Swing the grill up and forward. 

To remove the ballast box cover, unscrew the two hex head screws. A wiring diagram is located on the inside of the ballast cover. 

Use a slotted screwdriver and plastic mallet to drive out the knock-out on the left side of the ballast box. Install the grommet from the relay kit in the knock-out hole. Then mount the relay underneath the unit and to the left side of the ballast box. It should be ¾ inches from the front edge of the underside and anchored with two self-tapping screws, also in the kit. When the relay shield is installed, the relay and exposed wiring should be covered. 

Now it’s time to install the relay temperature control wiring. Feed the new wires through the knockout and into the ballast box. Connect the wires in the relay kit to the relay so that one black wire is connected to one of the normally-open contacts of the relay. Connect the other black wire to the other normally-open contact on the relay. Connect the pink wire to one side of the relay coil  

Note that the pink wire runs from the temperature control to the black compressor receptacle wire. In making this repair, you will cut this connection and connect the pink wire from the temperature control to the pink wire going to the relay. 

Now connect the white wire to the white bundle on the other side of the coil. It’s connected to the main power cord in the ballast box. Use the Sta-Con connectors included in the kit to make these connections. 

To replace the existing temperature control, connect one pink wire from the old control to terminal#4 on the new Danfoss temperature control, and the other pink wire from the old control to terminal #3 on the new control. 

Anchor the new relay by attaching it to the relay shield with two self-tapping screws. Make sure the shield covers the relay and all exposed wiring. 

Check the relay operation by unplugging the condensing unit from the compressor receptacle on the ballast box. Turn the new temperature control to zero by aligning the zero on the control knob with the arrow on the evaporator housing. Listen for a click to ensure it is in the off position. 

Then plug a voltmeter into the compressor receptacle and plug the cabinet into a power source. At this point, you may reinstall the ballast box cover, anchoring it with two screws. Check the voltage on the voltmeter that you just plugged into the compressor receptacle. The voltage should be the same as at the wall outlet. If so, remove the voltmeter, set the temperature control to zero, and plug the condensing unit cord back into the compressor receptacle. 

Replace the louvered grill and reconnect the power cord. Finally, set the temperature control to a normal setting and check the cabinet operation. 

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