Quick Answer
Okay, so here's the quick version. You got one room that's an icebox and the master bedroom is a sauna, right? Ninety percent of the time, the problem isn't the big, expensive unit itself. It's airflow. Plain and simple. Before you call anybody, go check that all your vents are open and not blocked by a new couch or something. Then, for the love of God, check your air filter. If it's clogged, you're choking your system. That's a $15 fix that solves half my service calls. If that doesn't work, you're likely looking at leaky ducts or an unbalanced system.
Common Symptoms
Possible Causes
Step-by-Step Diagnosis
Step 1
Walk around and physically check every single vent and return grille to make sure it's open and not blocked by anything.
Step 2
Pull out your air filter. If it's gray and caked with dust, replace it immediately with a standard pleated filter (MERV 6-8).
Step 3
Make sure your thermostat fan is set to 'AUTO', not 'ON'.
Step 4
Use a digital thermometer to measure the air temperature coming out of a 'good' vent and a 'bad' vent to confirm an airflow disparity.
Step 5
If you can do so safely, visually inspect accessible ductwork in your attic or crawlspace for obvious kinks, tears, or disconnected sections.
DIY vs Professional Costs
| Repair Type | DIY Cost | Professional Cost | Time Required |
|---|---|---|---|
Change Air Filter / Unblock Vents | $10-$50 | $75-$150 (Service Call) | 15 minutes |
Seal Accessible Duct Leaks | $20-$50 | $300-$1000 | 1-3 hours |
System Balancing / Damper Adjustment | $0 (Guessing) | $350-$800 | 2-4 hours |
Blower Motor or Capacitor Repair | N/A | $450-$1800 | 2-5 hours |
When to Call a Professional Hvac
- If you've already changed the filter and checked all the vents and the problem persists.
- You suspect major ductwork issues in an attic or crawlspace that are beyond a simple patch.
- Your HVAC unit is making loud or unusual noises like grinding, squealing, or banging.
- The outdoor AC unit or the copper lines leading to it are covered in ice.
- You're not comfortable working in your attic/crawlspace or dealing with anything beyond basic cleaning.
Prevention Tips
- Change your air filter every 1-3 months. It's the cheapest and most effective thing you can do.
- Schedule an annual HVAC tune-up with a reputable company to have coils cleaned and components checked.
- Periodically walk through your home and ensure furniture, drapes, and rugs haven't been pushed over vents.
- Seal air leaks around windows and doors with caulk and weatherstripping to reduce the load on your system.
- If your attic insulation is sparse or settled, consider adding more. It helps keep the conditioned air in and the outdoor heat out.
Frequently Asked Questions
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