MDB8959 Dishwasher — What Parts Fix Common Problems and How to Replace Them
Need the replacement part? Search your model number at for guaranteed fit and fast free shipping.
Understanding the Problem
What is MDB8959? MDB8959 is a dishwasher model prefix used on several Whirlpool/Maytag/Whirlpool-built machines. The most frequent repair areas on these machines are the door latch (won't start), drain pump (won't drain), main control board (erratic operation), and wash pump/motor (noisy or not washing). Step-by-step diagnostic and repair steps: 1) Identify the symptom precisely: does the dishwasher not start at all, not drain, not wash/heat, leak, or run but not complete cycles? Note any error codes or flashing LEDs on the control panel. 2) Locate model/serial tag: open the door and find the sticker on the tub/frame or edge of the door. Record full model number (often MDB8959xxxx) before ordering parts. 3) Check power and basic function: ensure the dishwasher has power, the circuit breaker/fuse is OK, and the door is closing/latching fully. A door that doesn’t latch prevents the unit from starting. 4) If it won't start but has power: inspect the door latch/strike for broken tabs or failed microswitch. Test continuity on the latch switch with a multimeter. Replace the latch assembly if the switch is open when the door is closed. 5) If it runs but won’t drain: remove the lower kickplate, remove water (siphon or towel), and check the drain hose for kinks or clogs. Then test the drain pump: with power off, remove the pump access (bottom) and check for foreign objects; test pump motor with a multimeter for continuity and test-run with power (careful) or replace if seized. 6) If it runs but doesn't wash/low spray: check the circulation (wash) pump and motor, spray arms for clogs, and the inlet valve (fills slowly or not at all). A bad wash motor will often hum or make grinding noises. 7) If heating / drying fails: test the heating element with an ohmmeter (low resistance means good; open = bad) and check the thermostat/thermal fuse or control board for faults. 8) If cycles are erratic or error codes appear: the user interface/control board or harness may be faulty. Visually inspect the main control board for burned spots or blown capacitors. Check ribbon cables and connectors; reseat them. If errors persist, replace the control board. 9) Replace parts: always buy exact OEM or compatible replacements for the full model number. Follow the replacement instructions below for common parts. 10) Final test: reassemble, restore power, run a short test cycle with no dishes to confirm the repair; check for leaks, proper drain, and that cycles complete. Basic how-to-replace examples (short): - Door latch: unplug power, open door and remove inner door panel screws to access latch, disconnect wiring harness, remove latch mounting screws, install new latch, reconnect harness, reassemble and test. - Drain pump: unplug power, remove lower kickplate/ access panel, place towels to catch water, disconnect drain hose and electrical connectors, unmount pump, install new pump, reconnect hose and wiring, reassemble and test. - Control board: unplug power, remove access panel (top or back depending on model), photograph wiring layout, unplug connectors and ribbon cables, remove board mounting screws, install new board, reconnect exactly, restore power and run test cycle. Safety note: Always disconnect power at the breaker before opening panels. Use a multimeter only if you are comfortable and know how to test live circuits safely. If you are uncertain, hire a qualified appliance technician.
Common Symptoms
Dishwasher won’t start, won’t drain, cycles stop mid-cycle, noisy during wash, not cleaning dishes, not heating/drying, or shows control-panel errors.
Common Causes
- Failed door latch or switch preventing the unit from starting
- Clogged or failed drain pump or blocked drain hose
- Faulty wash/circulation pump or motor
- Defective electronic control board or failed user interface
- Heating element, thermostat, or thermal fuse failure
Popular Parts That Fix This Problem
These are the most common replacement parts that fix this problem. When you're ready to order, click below to find the right part at ProsourceParts.com — just search by your appliance model number for a guaranteed fit.
Helpful Repair Tip
To confirm the faulty part: reproduce the symptom and then isolate the subsystem—e.g., for no drain, try a quick drain cycle and listen for the drain pump; if it’s silent and accessible, test pump continuity and try briefly powering the pump to see if it runs before replacing.
Frequently Asked Questions
How do I find the exact replacement part for my MDB8959 dishwasher?
Open the dishwasher door and locate the model/serial sticker on the tub’s rim or door edge. Record the full model/serial. Use that full model number when searching OEM part diagrams or entering into parts sites—many replacement parts look similar but are model-specific, so exact-match lookup prevents ordering the wrong item.
Can I replace the control board or pump myself or should I call a pro?
You can replace pumps, latches, and control boards yourself if you are comfortable with basic tools, safety (power off) and following step-by-step photos. Pumps and latches are straightforward. Control-board replacement requires careful handling of ribbon cables and correct reconnection; if you’re unsure, especially with electrical testing or warranty concerns, hire a qualified appliance technician.
Related How-To Videos
Real DIY Repair Stories
Be the first to share your repair story!
Share Your Repair Story
Your experience helps other homeowners fix their appliances. Tell us how it went!
Can't Fix It Yourself? Find a Local Technician
It's perfectly okay to call a professional. Some repairs require specialized tools, deep teardowns, or dealing with complex systems that are better left to the pros.
Find the Right Part for Your Appliance
Don't guess — search your exact appliance model number at ProsourceParts.com to find the correct OEM compatible replacement part. They offer fast free shipping, guaranteed fit, and thousands of parts in stock.
Your Free Parts Videos
Whether your dishwasher won't drain, your dryer stopped heating, or your fridge isn't cold, we've created simple repair guides for the most common appliance problems homeowners face. Each guide explains what's going wrong, the most likely causes, and which replacement parts fix the issue. When you're ready to order, we link directly to ProsourceParts.com where you can search by model number and get the right part shipped fast.