Restore Defrost Control Bosch 800 Series Model 8007317

Introduction

A refrigerator that keeps your food cold and fresh is a cornerstone of every modern kitchen. In the Bosch 800 Series, the defrost control plays a vital role in preventing frost buildup in the freezer and ensuring the compressor runs efficiently. When this control fails, ice can accumulate, food can spoil, and energy consumption can spike. Fortunately, restoring the defrost control on a Bosch 800 Series model 8007317 is a task that many homeowners can handle with a bit of patience and the right tools.

In this guide we will walk you through every step of diagnosing, cleaning, testing, and replacing the defrost control. We’ll also cover common pitfalls, preventive maintenance, and when it’s time to call a professional. By the end, you’ll have a clear understanding of how the defrost system works and the confidence to keep your refrigerator running smoothly.

Understanding the Bosch 800 Series Defrost System

The Bosch 800 Series uses an automatic frost‑free cycle. The core components of this cycle include:

• Defrost Thermostat – monitors the temperature in the freezer and signals the control when the set point is reached.
• Defrost Relay – controls the heating element that melts the ice.
• Defrost Control (or Control Board) – the logic unit that coordinates the thermostat, relay, and compressor.

The defrost control is often located near the back of the refrigerator, behind a small access panel. Its job is to read the thermostat, time the defrost sequence, and ensure the compressor doesn’t run while the freezer is thawing.

When the control malfunctions, you may notice:

• Excessive ice on the freezer walls
• The compressor running continuously
• The refrigerator failing to cool properly
• Unusual noises or a burning smell

Understanding how these parts interact helps you pinpoint the problem and take appropriate action.

Symptoms of a Faulty Defrost Control

Before you start, it’s useful to confirm that the defrost control is the culprit rather than another component. Common symptoms include:

• Frequent or prolonged defrost cycles – The fridge seems to be constantly on a defrost cycle, which drains battery life and leaves the unit warm.
• Freezer temperature rise – Even when the fridge door is closed, the freezer fails to reach the target temperature (usually around 0°F or –18°C).
• Ice build‑up – Thick ice accumulates on the evaporator coils or the back of the freezer.
• Compressor stalls – The compressor may turn on and off irregularly, or it may stay on continuously during a defrost cycle.

If you notice one or more of these signs, proceed to the troubleshooting steps below.

Tools and Parts Needed

Before you begin, gather the following items:

• Screwdrivers – Phillips and flathead for removing panels.
• Multimeter – For testing continuity and resistance on the defrost control and relay.
• Replacement defrost control – Make sure it’s the exact part for Bosch 800 Series model 8007317.
• Safety gloves and glasses – Protect your hands and eyes during the repair.
• Towel or rag – Keep a clean surface for parts and to wipe moisture.
• Compressed air – Optional, to clear dust from connectors.

Having everything ready saves time and reduces the risk of damaging components.

Safety Precautions

Safety should always come first when working with appliances that contain electrical components and refrigerant. Follow these precautions:

1. Unplug the unit – Disconnect the refrigerator from the mains before touching any wiring or internal parts.
2. Avoid touching exposed wiring – Once the fridge is unplugged, the internal circuits are low voltage, but it’s best to keep your hands away from live wires.
3. Work in a dry area – Moisture can cause short circuits.
4. Keep a clear workspace – Avoid clutter that could obstruct your view or lead to accidental contact with moving parts.

By taking these simple steps, you reduce the risk of injury and protect the appliance from accidental damage.

Locating and Inspecting the Defrost Control

Step 1 – Unplug and Prepare

1. Move the refrigerator away from the wall to give yourself space.
2. Disconnect the power cord from the wall outlet.
3. Leave the unit standing upright to avoid shifting internal components.

Step 2 – Remove the Back Panel

1. Use the appropriate screwdriver to remove the screws holding the rear panel.
2. Carefully lift the panel away to expose the internal wiring and the defrost control board.
3. Note the orientation of the control board and any cable connectors before disconnecting them.

Step 3 – Visual Inspection

With the panel removed, examine the defrost control for:

• Cracked or melted plastic – A sign of overheating or short circuits.
• Loose or disconnected wires – Check for any cable that has come loose.
• Physical damage to connectors – Oxidized or corroded contacts can impair function.

If you spot any obvious damage, it’s often best to replace the control rather than attempt to repair it.

Testing the Defrost Control with a Multimeter

A multimeter allows you to determine whether the control is functioning correctly by measuring resistance and continuity.

Setting Up the Multimeter

1. Turn the multimeter to the Continuity or Ohms setting.
2. Ensure the probes are connected correctly—red probe to the positive terminal and black to the negative.

Testing the Thermostat Connection

1. Locate the thermostat connection on the control board.
2. With the refrigerator still unplugged, touch the probes to the thermostat terminals.
3. The multimeter should show a low resistance value (typically below 1,000 ohms).
4. If the reading is infinite or shows no continuity, the thermostat is likely faulty.

Testing the Relay Connection

1. Identify the relay contacts on the board.
2. Measure resistance between the relay terminals while the fridge is unplugged.
3. A correct relay will show a specific resistance value as per the manufacturer’s specifications (consult the service manual).
4. If the reading is wrong or shows a short, replace the relay or the entire control board.

Checking for Shorts

1. With the board still unplugged, touch the probes to each contact point.
2. Look for any unintended continuity between normally isolated points—this indicates a short.

If any of these tests fail, the defrost control is most likely defective and needs replacement.

Replacing the Defrost Control

Step 1 – Remove the Old Control

1. Disconnect all wiring harnesses from the control board.
2. Carefully note the orientation of each connector for the replacement.
3. Remove any screws or mounting brackets that hold the control board in place.
4. Gently lift the board out of its housing.

Step 2 – Install the New Control

1. Place the new defrost control board in the same orientation as the old one.
2. Secure it with the original screws or mounting hardware.
3. Reconnect all wiring harnesses, ensuring each plug is fully seated.
4. Verify that no wires are pinched or twisted.

Step 3 – Test the Replacement

1. Reconnect the power briefly to test the new control.
2. Observe whether the fridge begins a normal defrost cycle and whether the compressor behavior returns to normal.
3. If everything appears functional, proceed to reassemble the refrigerator.

Step 4 – Reassemble the Refrigerator

1. Replace the back panel and secure it with screws.
2. Move the refrigerator back into position.
3. Plug the unit back into the wall outlet.
4. Allow a few minutes for the compressor to cycle and for the fridge to begin cooling.

Troubleshooting Common Issues After Replacement

Even after installing a new defrost control, some issues can persist. Here’s what to check:

• Loose Wiring – A loose connection can cause intermittent faults. Re‑inspect all plugs.
• Defrost Relay Failure – The relay might be burnt out; replace if necessary.
• Thermostat Malfunction – If the thermostat is still faulty, replace it.
• Air Flow Problems – Ensure that the evaporator fan is running; a blocked fan can mimic defrost issues.
• Electrical Supply Issues – Verify that the outlet supplies the correct voltage and that the circuit breaker hasn’t tripped.

If after these checks the problem remains, consider consulting a professional technician.

Preventive Maintenance Tips

Keeping your Bosch refrigerator in top condition reduces the likelihood of defrost control failures. Follow these simple habits:

• Clean the Evaporator Coils – Dust buildup reduces heat transfer and can cause the compressor to work harder. Clean the coils every six months with a coil brush.
• Check Door Seals – Leaky seals let warm air in, forcing the compressor to compensate. Replace any worn door gaskets.
• Maintain Proper Temperature Settings – Keep the freezer at 0°F and the fridge at 35–38°F.
• Avoid Overloading – A full fridge can restrict airflow, leading to uneven cooling and increased defrost cycles.
• Regularly Inspect Defrost Heater – Visually inspect for burn marks or discoloration; replace if you see any damage.

By performing these preventive steps, you can extend the life of your refrigerator’s defrost system.

When to Call a Professional

If you’ve followed all the steps above and the refrigerator still shows symptoms of a faulty defrost control, or if you’re uncomfortable working with electrical components, it’s time to call an HVAC or appliance technician. Professionals have the tools and expertise to:

• Diagnose complex electrical issues
• Service the compressor or refrigerant lines
• Verify the safety of the appliance after repairs

Remember, safety first—if the unit is still under warranty, contacting Bosch support can also help you get a replacement part without incurring repair costs.

Final Thoughts

The defrost control is a critical component of the Bosch 800 Series refrigerator’s efficiency and longevity. By understanding how it works, recognizing its failure signs, and following a systematic repair process, you can often restore your fridge’s performance without professional help. Remember to keep your tools handy, work safely, and perform regular maintenance to keep the system running smoothly.

A well‑maintained refrigerator not only preserves food but also saves energy and money. So, if your fridge has been acting up, take a moment to dive into this guide, tackle the issue head‑on, and enjoy the satisfaction of a properly cooled kitchen again.