Types of AC Repairs: From Compressor Replacement to Refrigerant Recharge

 

Your Complete Guide to Common Air Conditioning Repairs

By Stan Johnson | Master HVAC Technician & Educator

Your AC isn’t cooling like it used to—now what? Air conditioning systems can fail in dozens of ways, and not all repairs are created equal. Some are quick, affordable fixes, while others (like a dead compressor) can cost as much as a new unit.

As an HVAC pro with 20+ years in the field, I’ve tackled every type of AC repair imaginable. In this guide, I’ll break down the most common AC repairs, how to spot them early, and what they typically cost. Whether you're a homeowner trying to diagnose an issue or a new tech learning the ropes, this is your go-to reference.

---

1. Refrigerant Recharge (When Your AC is Low on Coolant)

Symptoms:

• Weak cooling performance

• Hissing or bubbling noises

• Ice buildup on refrigerant lines

Cause: Refrigerant doesn’t get "used up"—if levels are low, there’s a leak that must be fixed first.

Repair Process:
✔ Locate and repair the leak (UV dye or electronic detector)
✔ Evacuate and recharge with the correct refrigerant type (R-22, R-410A, etc.)

Cost: $200\text{–}$600 (depending on refrigerant type and leak location)

Pro Tip: Never just "top off" refrigerant—EPA regulations require leak repairs first.

---

2. Capacitor Replacement (The #1 Cause of AC Not Starting)

Symptoms:

• AC hums but won’t turn on

• Frequent breaker trips

• Intermittent cooling

Cause: Capacitors weaken over time, especially in heatwaves.

Repair Process:
✔ Discharge old capacitor
✔ Replace with matching µF and voltage rating

Cost: $100\text{–}$300 (DIY part: $15\text{–}$50)

Real-World Example: Last summer, I replaced 47 capacitors in one month—heat kills them fast!

---

3. Contactor Replacement (Burnt Electrical Switch)

Symptoms:

• AC clicks but doesn’t start

• Erratic operation

Cause: Electrical arcing burns the contacts over time.

Repair Process:
✔ Turn off power
✔ Swap contactor (single vs. double pole)

Cost: $150\text{–}$400 (Part: $25\text{–}$80)

Pro Tip: Ants love nesting in contactors—a common cause of failure in humid climates.

---

4. Evaporator or Condenser Coil Cleaning/Repair

Symptoms:

• Reduced airflow

• Frozen coils

• Higher energy bills

Cause: Dirt buildup or refrigerant leaks (coils often corrode).

Repair Process:
✔ Chemical cleaning for mild buildup
✔ Coil replacement if leaking or severely damaged

Cost: Cleaning ($100\text{–}$300) | Replacement ($1,000\text{–}$2,500)

---

5. Compressor Replacement (The "Heart Transplant" of AC Repairs)

Symptoms:

• Loud humming but no cooling

• Tripped breaker

• AC blows warm air

Cause: Electrical failure, refrigerant issues, or old age.

Repair Process:
✔ Recover refrigerant
✔ Swap compressor (often requires new filter drier)
✔ Recharge system

Cost: $1,500\text{–}$3,500 (Sometimes better to replace the whole unit)

Hard Truth: 70% of compressor failures are caused by dirty coils or low refrigerant.

---

6. Drain Line Clog Clearance

Symptoms:

• Water leaking indoors

• Musty smells

• AC shuts off randomly

Cause: Algae or mold buildup in the condensate line.

Repair Process:
✔ Vacuum out clog
✔ Pour vinegar or bleach to prevent recurrence

Cost: $75\text{–}$200 (DIY fix: $5 for a wet/dry vac)

---

7. Thermostat Replacement/Repair

Symptoms:

• Incorrect temperature readings

• AC not responding

• Short cycling

Cause: Dead batteries, faulty wiring, or aging electronics.

Repair Process:
✔ Check wiring connections
✔ Upgrade to a smart thermostat (Nest, Ecobee)

Cost: $100\text{–}$500 (Basic model: $50\mathrm{\mid }Smart:$150–$300)

---

8. Ductwork Repairs (The Hidden Problem)

Symptoms:

• Uneven cooling

• High energy bills

• Whistling noises

Cause: Leaks, poor insulation, or collapsed ducts.

Repair Process:
✔ Seal leaks with mastic (not duct tape!)
✔ Replace damaged sections

Cost: $300\text{–}$1,500 (Depends on accessibility)

---

When to Repair vs. Replace Your AC

Repair	Replace
Under 10 years old	Over 12–15 years old
Single component failure	Compressor + refrigerant leak
$500 or less repair	Repair costs >50% of new unit

Rule of Thumb: If repair costs exceed $2,000, consider a new system for better efficiency.

---

Final Thought: Maintenance Prevents Most Repairs

✔ Annual tune-ups catch small issues early
✔ Clean filters monthly
✔ Keep coils debris-free

Read more: Common AC Problems and How to Fix Them

Dealt with a crazy AC repair? Share your story below!