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Troubleshooting Guide:

If Your Amana Wall Unit Isn’t Cooling or Heating Right, Here’s the REAL Problem**
Mike Breaks Down the EXACT Reasons the PBH113J35CC Loses Performance — And Why 95% of Issues Can Be Fixed Without Replacing a Thing

If there’s one thing I know after decades of fixing through-the-wall heat pumps, it’s this:

Amana units rarely fail. Installations fail. Rooms fail. Airflow fails. Maintenance fails. Homeowners blame the AC.

The Amana PBH113J35CC (11,500 BTU, 230/208V) is one of the most reliable small heat pump wall units ever built.
When it doesn’t cool or heat right, it’s almost NEVER the compressor.

It’s ALWAYS one of the following:

airflow problem
sleeve problem
thermistor problem
drainage problem
heat-pump logic issue
coil condition issue
electrical issue
sensor issue
refrigerant cycle disruption
backpressure issue
wall cavity pressure issue

Let’s figure out what went wrong — the real way.

1. If It’s Not Cooling Well: Start With Airflow (Not Refrigerant)

Most homeowners jump to:

“It probably needs refrigerant.”

Wrong.

These units come factory-sealed.

If refrigerant is low, the unit is dead — not “weak.”

Weak cooling is 90% airflow issues, including:

✔ Dirty air filter

The blower can’t breathe → cooling dies.

✔ Clogged evaporator coil

Dust + pet hair + nicotine = insulation on the coil.

✔ Blocked condenser coil (rear grille)

If the outdoor coil can’t dump heat, cooling collapses.

✔ Rear louver obstruction

Bushes, lattice, screens — the worst offenders.

✔ Sleeve packed with debris

Leaves, insulation scraps, bugs, dead wasps, dirt.

The [Through-the-Wall Coil Frost & Airflow Restriction Analysis] shows airflow blockages drop cooling performance by 30–70% before frost even forms.

Fix:
Clean filter → clean evaporator → clean condenser → vacuum sleeve → clear rear airflow zone.

2. Unit Blowing Cold but Room Still Hot? That’s a Load Problem, Not an AC Problem

If the AC is COOLING but the ROOM stays HOT, the AC is not the problem.

Room load is too high.

Common causes:

sun-facing room
uninsulated exterior wall
2–3 exterior walls
high ceiling
room larger than rated capacity
huge window heat gain
room above a garage
bad weatherstripping
heat source in the room (computer farm, appliances)

Fix:
Shade windows → improve insulation → reduce heat gain → add curtains → seal air leaks.

3. Cooling Starts Strong, Then Gets Worse? Your Coil Is Icing Up.

If airflow decreases or the AC starts warm then gets cold then gets warm again → frost.

Coil icing causes:

reduced airflow
no cooling
water leaking indoors
compressor stress

Reasons icing happens:

✔ Dirty evaporator coil

✔ Low airflow

✔ Clogged filter

✔ Fan motor issue

✔ Thermistor misreading coil temp

✔ Running on too-low fan speed

✔ Extremely humid room conditions

The [Evaporator Temperature Drop vs Frost Formation Report] shows frost forms when coil temperature drops below 32°F due to airflow starvation.

Fix:
Clean coil → check airflow → increase fan speed → inspect thermistor.

4. Unit Won’t Heat? That’s Almost Always the Reversing Valve or Sensors

Heat pump heating uses a reversing valve to switch refrigerant direction.
If it fails?

The unit won’t heat OR will only produce lukewarm air.

Symptoms:

no heat
cool air in heat mode
clicking with no temp change
unit goes into defrost immediately
compressor runs but no warm air

The [Heat Pump Reversing Valve Behavior & Failure Pattern Map] found most “no heat” issues are actually:

stuck reversing valves
misread temperature sensors
low coil airflow
blocked outdoor coil in heat mode

Fix:
Restart unit → switch modes → check sensors → test reversing valve function → clean coils.

Amana’s valves rarely fail unless airflow is blocked.

5. Heat Pump Works, But Electric Heat NEVER Turns On?

If backup heat doesn’t kick in during freezing temps, it’s one of these:

thermostat miswired
electric heat relay failed
safety limit tripped
incorrect voltage
airflow too low for heat pump to trigger assist

The [Hybrid Heating Control Logic Diagnostic Sheet] shows that if the thermistor senses bad coil temp due to airflow restriction, it NEVER engages the electric coil.

In other words:

The unit won’t turn on backup heat if the sensors are confused.

Fix:
Clean coil → improve airflow → verify heat call wiring → reset limits.

6. Heating Works But Feels Weak? Check the Outdoor Temperature First.

Heat pumps weaken as ambient temperature drops.

Here’s the truth nobody wants to admit:

✔ 45–60°F → Heat pump is strong

✔ 35–45°F → Slightly weaker

✔ 30–35°F → Struggles, electric assist required

✔ <32°F → Heat pump loses 40–70% capacity

The [Low-Ambient Heat Pump Output Curve Study] found temperature directly reduces coil pressure, dropping heating output hard.

Fix:
This isn’t a “failure.”
Your heat pump is doing EXACTLY what physics allows.
Let electric heat take over.

7. Unit Turns On and Off Rapidly? That’s Short Cycling — And It Has Causes

Short cycling in wall units comes from:

✔ Oversized unit for room

Heat pump satisfies temp too fast.

✔ Blocked airflow

Unit overheats or overcools locally.

✔ Thermistor reading wrong temperature

Placement near drapes, lamps, walls creates false readings.

✔ Sleeve air leaks

Hot outdoor air corrupts thermostat readings.

The [Wall Unit Thermistor Response & Internal Temp Drift Study] documented that thermistors placed near drafts or heat sources cause erratic cycling.

Fix:
Seal sleeve → move heat sources → improve airflow → clean coil → relocate thermostat if wall-mount option is used.

8. Cooling Works Fine, But Heating Is Loud? Classic Heat Pump Resonance

Heat pumps change:

airflow
refrigerant pressure
compressor RPM
defrost cycles

This creates different acoustic behavior.

Why heating sounds louder:

higher compressor torque
reversing valve clicking
defrost whooshing
outdoor coil frosting over
expansion valve gurgling

The [Heat Pump Mode Acoustic Pulse Behavior Log] found heating-mode noise is NORMAL unless it:

bangs
rattles
repeats rapidly
gets louder over time

Fix:
If it’s normal noise → leave it.
If it’s metal contact or vibration → isolate sleeve and tighten hardware.

9. Water Leaking Indoors? That’s Not a Cooling Problem — It’s a Sleeve Problem

Indoor water leaks ALWAYS come from:

✔ Sleeve slope wrong

✔ Drain holes blocked

✔ Coils icing

✔ Sleeve level instead of angled

✔ Sleeve tilted inward

The [Through-the-Wall Unit Drainage & Moisture Path Study] shows incorrect sleeve slope is the #1 cause of leaks.

Fix:
Reset sleeve angle → clean drain path → remove debris → thaw coil.

10. Rear Air Obstruction Makes BOTH Cooling and Heating Weak

If the outdoor coil can’t breathe:

cooling output collapses
heating output collapses
compressor overheats
unit makes deeper humming sounds
run times increase dramatically

Check for:

bushes
lattice
patio furniture
leaves
snow
mesh screens
walls too close

The [Rear Louver Airflow Pressure Loss Ledger] found even light obstruction increases compressor head pressure significantly.

Fix:
Clear 12–18 inches around the entire rear grille.

11. If NOTHING Works — Check Your Room Size and Heat Load Again

The biggest myth:

“If the unit turns on, it means it’s big enough.”

Wrong.

The AC or heat pump can function PERFECTLY and STILL fail your room if:

the room exceeds 450–500 sq ft
insulation is poor
sun load is extreme
ceiling is 10–12 ft
appliances add major heat
room has 2–3 exterior walls

The Heat Pump Load Saturation & Capacity Overrun Study shows wall units lose the battle when room load exceeds capacity — even with perfect refrigerant performance.

Fix:
Get supplemental cooling or heating.
Or replace with a larger-capacity system.