Fixing defrost timer and thermosta

To test the defrost timer:

1. Step 1: Unplug the refrigerator.
2. Step 2: Disconnect the wires from the timer and timer motor. ...
3. Step 3: Test the defrost timer with a VOM set to the RX1 scale. ...
4. Step 4: Connect the new defrost timer the same way the old one was connected.

https://home.howstuffworks.com/how-to-repair-a-refrigerator5.htm

How to Test your Defrost Timer - YouTube

? 5:55
www.youtube.com/watch?v=-L80Fk5had4
Sep 29, 2013 - Uploaded by Bill Newberry Video describing how to test the defrost timer on your refrigerator. ... output before u replace thermosta & the heater or any component u have to ...

check the defrost timer, defrost terminator, thermistors and the tempeture control thermostas also check the vent damper? open or close to much

See defrost timers and wiring diagrams and manuals
http://waterheatertimer.org/Paragon-timers-and-manuals.html#defrost

You posted under 8145-20

8145-20 is time initiated, temperature or pressure terminated.
Defrost timer training pdf

The 8145-20 timer:
Power leads connect to terminals 1 and N.
For 120Volt circuit: L is black hot wire to terminal 1, N is white neutral wire to terminal N
For 240Volt circuit: L1 and L2 are the hot leads from 240V breaker


'NO' means normally open, so terminal 3 turns ON only when timer turns on (that is 'time initiated')
So the hot gas valve for defrosting is connected to terminal 3 and turns ON when timer turns ON.
The other wire from hot gas valve connects to terminal N where it completes the circuit

'NC' means normally closed, so terminal 4 is ON at all times EXCEPT when timer turns ON.
That means fan is ON all the time, except when time initiated sequence begins, and then fan turns OFF while hot gas valve is defrosting unit.
The other wire from fan connects to terminal N where it completes the circuit

The cycle limit switch is connected to terminal X.
This is the switch that terminates the defrost sequence and turns timer OFF
Other wire from cycle limit switch connects to terminal N where it completes the circuit

I also suggest you ask a paid fixya experts who can provide additional information by phone.
Paid experts will not answer your question unless they know the answer, and if their answer is not complete, then fixya offers money back guarantee.

The 8045-20 & 8145 are 240V timers.
My maintenance buddy at McDonalds says the defrost timers are interchangeable, BUT I have not wired these particular timers.
You may want to post your question to a paid answerer who specializes in refrigeration:

This being said:
The 8045 is for 'Electric Heat Defrosting'
The 8145 is for 'Hot Gas Defrosting'

I posted the manual:
http://waterheatertimer.org/pdf/8000-series-defrost-sell-sheet.pdf

I also posted the 8145 and 8045 wiring side by side:
http://waterheatertimer.org/Paragon-timers-and-manuals.html#8045

The wiring changeover looks like the following:
Hot1 on 8045 is connected to terminal N => move this wire to terminal 1 on 8145
There is a jumper plate on 8045 that connects terminals 1 N 2
Jumper plate on 8145 connects terminals 1 and 2
If jumper plate is missing on 8145, use jumper wire to connects terminals 1 and 2
Hot2 on 8045 is connected to terminal X => move this wire to terminal N on 8145
Other wires on 8045 that are connected to terminal X => move to terminal N on 8145
Thermostat on 8045 is connected to NC terminal 4 => move this wire to NC terminal 4 on 8145
Heater on 8045 is connected to NO terminal 3 => move this wire to NO terminal 3 on 8145
Terminal X on 8145 is bare since this goes to cycling limit switch which is not used on 8045

The wiring diagrams appears below:

Link below has 8145-20 wiring diagram:
http://waterheatertimer.org/Paragon-timers-and-manuals.html#defrost

Terminal N is 2nd wire needed to complete circuit.
In 240V 8145-20, there are two hot wires.
One Hot connects to terminal 1, with jumper to terminal 2.
Second Hot connects to terminal N, and this will power the clock motor and timer.
Terminal X is for temperature or pressure termination switch.

Defrost cycle works like this:
Timer is running but switched OFF.
Refrigeration fan is ON.
Timer switches ON, defrost cycle begins.
Refrigeration fan turns OFF.
Hot gas defrost turns ON.
When temperature-or-pressure limit switch reaches trip point, it switches timer OFF.
Refrigeration fan turns ON again.
Hot gas defrost turns OFF.

you might have a defrost problem. Frost free models have a heating element that is controlled by a timer to automatically defrost ice, defrost timer turns on defrost heating element every 12 hours to melt ice in freezer and allow good air flow.
You can test defrost element with an ohm meter(located inside freezer coils-will have two wires going to a plug connection), if OK replace defrost timer (located in various places depending on make and model

sounds more like a defrost problem, check your defrost timer, defrost heaters.

hi If the compressor doesn't run, it is likely that the defrost timer is malfunctioning. This part is located near the compressor. To test the defrost timer:
Step 1: Unplug the refrigerator.

Step 2: Disconnect the wires from the timer and timer motor. Remove the timer from its brackets by backing out two retaining screws.

Step 3: Test the defrost timer with a VOM set to the RX1 scale. Clip one probe of the VOM to each defrost timer -- not motor -- wire, and turn the timer control screw shaft until it clicks. If the defrost timer is functioning, the meter will read zero. If the needle jumps, the defrost timer is faulty. Replace it with a new one of the same type.

Step 4: Connect the new defrost timer the same way the old one was connected.

To check the defrost timer motor, clip one probe of the VOM to each motor wire, setting the scale to RX100. If the meter reads between about 500 and 3,000 ohms, the motor is functioning properly. If the meter reads higher than 3,000 ohms, the timer motor is faulty. Replace it with a new one of the same type. Connect the new motor the same way the old one was connected.

hi If the compressor doesn't run, it is likely that the defrost timer is malfunctioning. This part is located near the compressor. To test the defrost timer:
Step 2: Disconnect the wires from the timer and timer motor. Remove the timer from its brackets by backing out two retaining screws.
Step 3: Test the defrost timer with a VOM set to the RX1 scale. Clip one probe of the VOM to each defrost timer -- not motor -- wire, and turn the timer control screw shaft until it clicks. If the defrost timer is functioning, the meter will read zero. If the needle jumps, the defrost timer is faulty. Replace it with a new one of the same type.
Step 4: Connect the new defrost timer the same way the old one was connected.
To check the defrost timer motor, clip one probe of the VOM to each motor wire, setting the scale to RX100. If the meter reads between about 500 and 3,000 ohms, the motor is functioning properly. If the meter reads higher than 3,000 ohms, the timer motor is faulty. Replace it with a new one of the same type. Connect the new motor the same way the old one was connected.