How to Install Room Air Conditioner Heater High-Limit Thermostat WP28X10013 in a GE Air Conditioner

Quick answer: Unplug the unit, remove the front grille and slide the chassis out of the sleeve, find the disc thermostat screwed to the heater assembly bracket, move its two wires to the new thermostat, screw it in the same spot, reassemble and run heat mode to confirm it cycles.

Heater high-limit thermostat WP28X10013 is the safety switch on the electric heater of a GE room air conditioner with heat. It sits against the heater coil assembly and opens the heater circuit if the coils get too hot, for example when airflow is blocked by a dirty filter. When the thermostat fails open, the unit cools normally but blows only room-temperature air in heat mode; when it sticks closed, the heater can overheat and trip the unit's other protection.

This guide applies to GE through-the-wall and window units with heat such as AZ29E07EACM1, AZ22E12D3BM3 and AZ35H09D5BM1. The repair itself is a simple two-wire swap, but reaching the part requires sliding the whole chassis out of its sleeve, which is heavy and awkward on a wall-mounted unit. Have a helper and a sturdy table or sawhorses ready to support the chassis while you work.

See part details and every compatible model: WP28X10013

⚠️ Safety First
  • Unplug the air conditioner from its dedicated outlet before removing any panel; heater circuits carry high current.
  • Wait for the heater coils to cool completely if the unit was recently running in heat mode.
  • The chassis is heavy and the fins are razor sharp; wear gloves and lift with a helper.
  • Discharge any run capacitor with an insulated screwdriver across its terminals before reaching near the compressor wiring.

Tools and Parts You Need

  • Phillips and flat-blade screwdrivers
  • Quarter-inch and five-sixteenths nut drivers
  • Needle-nose pliers for slide-on terminals
  • Multimeter for continuity checks
  • Flashlight
  • Work gloves and safety glasses

Step-by-Step Installation

  1. Unplug and remove the front grille Pull the plug from the wall outlet and set the room control to off. Release the clips or screws at the bottom of the front grille, tilt it forward, and lift it off the cabinet.
  2. Slide the chassis out Remove the screws that fasten the chassis to the sleeve or cabinet, usually along the front frame. With your helper, pull the chassis straight out and set it on a padded table so the rear coil hangs over the edge and is not bent.
  3. Locate the heater assembly Look behind the indoor coil and blower for the electric heater, a bank of coiled wire elements in a metal frame. The high-limit thermostat is a small round disc with two terminals screwed to a bracket on this frame.
  4. Photograph and disconnect the wires Take a photo of the two wires on the thermostat so their positions are recorded. Grip each slide-on terminal with needle-nose pliers and pull it straight off; do not pull on the wire insulation.
  5. Remove the old thermostat Unscrew the two mounting screws holding the disc to the bracket and lift the thermostat off. Check the bracket and heater frame for discoloration that would point to airflow problems.
  6. Install WP28X10013 Set the new thermostat on the bracket with its sensing face toward the heater exactly as the old one sat, and drive the two screws snug. Push the two wires onto the terminals until they seat firmly.
  7. Slide the chassis back in With your helper, guide the chassis into the sleeve, watching that no wires are pinched at the front frame. Replace the chassis screws and clip the front grille back on.
  8. Test heat and cool Plug the unit in, run cool mode for a minute, then switch to heat and wait for warm air at the discharge. Let it run a while to confirm the heater stays on under normal airflow and the unit does not shut down.

Fit Checks Before You Call the Job Done

  • The new thermostat body sits flat on the bracket in the same orientation as the original.
  • Both slide-on terminals grip tightly and cannot be pulled off by hand.
  • The wires follow the original route and are clear of the heater coils and blower wheel.
  • A continuity test across the thermostat terminals at room temperature shows a closed circuit.
  • The chassis slides fully into the sleeve and all frame screws line up with their holes.

Common Mistakes to Avoid

Skipping the photo The two wires look alike but the thermostat may sit in series with a specific element. Photograph before disconnecting so the wiring returns exactly.

Pulling the chassis alone A room unit with heat is heavier than it looks and the coils bend easily. Use a helper and support the whole chassis on a table.

Reusing burnt terminals Heat-darkened or loose spade connectors cause hot spots and repeat failures. Crimp new terminals on the wire ends if the old ones are discolored.

Ignoring the reason it tripped A high-limit that opened repeatedly points to a filthy filter or blocked coil. Clean the airflow path or the new thermostat will suffer the same fate.

Troubleshooting After Installation

Still no heat after replacement Check the heater elements for continuity and inspect the heat relay on the control board; an open element or relay will mimic a bad thermostat.

Heater runs briefly then shuts off The high-limit is doing its job because airflow is low. Wash the filter, clean the indoor coil, and make sure the blower wheel spins freely.

Unit trips the breaker in heat mode A wire is shorted to the frame, probably pinched when the chassis was slid in. Unplug, pull the chassis, and inspect every wire near the front frame.

Care Tips After the Repair

  • Wash or replace the air filter monthly during the heating season to keep airflow strong across the heater.
  • Vacuum the indoor coil and blower at the start of each season so the heater is never starved of air.
  • Keep curtains and furniture clear of the discharge grille to prevent heat backing up into the unit.

Compatible Models (Sample)

This part is listed for 71 GE models in our fitment data. Always confirm your exact model number on the appliance's rating plate.

Repair Difficulty and Time

Difficulty: Moderate. Typical time: 45 to 75 minutes.

Frequently Asked Questions

Can I test WP28X10013 before installing it?

Yes. At room temperature a multimeter on continuity should show a closed circuit across the two terminals. An open reading means the thermostat is bad.

Do I really have to pull the whole chassis out?

On most GE units with heat the heater sits behind the indoor coil and is not reachable from the front. Sliding the chassis out is the only safe access.

Why does the unit cool fine but not heat?

Cooling uses the compressor and does not pass through this thermostat. Only the electric heater circuit is interrupted when the high-limit opens.

Final Checklist

  • Unit unplugged and heater coils cool
  • Front grille removed and chassis slid out with a helper
  • Photo taken of the two thermostat wires
  • Old thermostat removed and bracket checked for heat damage
  • New thermostat mounted in the same orientation with both screws snug
  • Terminals pushed on firmly, wires clear of coils and blower

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