You hold a piece of paper up to the return grille and it barely sticks. The system is starving for air.
You probably came here because…
- The paper test at the return grille shows weak suction
- The system runs but rooms far from the unit stay hot or cold
- The AC may be freezing up or the furnace short-cycling
- You may hear the blower motor running loud
What’s actually happening
A starved-for-air HVAC system will kill parts fast. AC coils freeze, furnaces overheat, blower motors burn out from working against high static pressure.
Three usual causes: a filter that's way too restrictive for the system (people install MERV 16 filters in systems designed for MERV 8), ductwork that's too small for the system (common in older homes), or a blower motor that's failing and can't move air at rated capacity.
The 'too small ductwork' one is really common when someone upsized the AC or furnace but didn't upgrade the ducts. New 4-ton unit trying to breathe through 2-ton ducts.
What we do about it
Try a lower-MERV filter
If you're running MERV 13 or higher, drop back to MERV 8-11 for a test. If airflow improves noticeably, your system can't handle the higher-restriction filter and you either need a bigger filter housing or a lower MERV.
Count your returns
How many return grilles do you have in the whole house? If you have a big system and only one central return, that's your problem. Adding returns costs less than most people think and dramatically improves comfort.
Check blower speed
Multi-speed blowers can be set wrong at installation. A tech can move the wire tap to a higher speed setting – takes 5 minutes and can fix airflow without any duct work.
When to just call
If your ductwork is genuinely undersized, retrofit is possible but not cheap. Before you go there, we'll rule out cheaper fixes – filter, blower speed, adding a return. Call (423) 637-1846.
Ready to fix it?
Call the family that’s been doing this in the Sequatchie Valley since 1996.