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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Heat on but no air blowing

Customer Question

Our Heat pump is not blowing any air. We can hear air being sucked through the air return and the unit outside seems to be running (i.e. the fan is running), but no air is being blown through the vents at all. We had a couple of cold days last week and used the heat. Everything worked great. Now the temperature is back to warm and we need the ac. If you change to heat, still no air blows.

We have turned off the unit and are running the fan in case it is a frozen coil. Do you have any other suggestions?

Submitted: 7 years ago.
Category: HVAC
Expert:  Jack Pearce replied 7 years ago.

Are you still not getting any air flow? If not how long have you not gotten any air, and how long since you just have your fan running?

Customer: replied 7 years ago.

We have had the fan (only) running for two hours now. There seems to be a small improvement in air flow not much. I’m not sure how long we haven't been getting much air we noticed it about 3.5 hours ago.

Expert:  Jack Pearce replied 7 years ago.

You are probably going to have to run it several more hours. It does sound as if your coil is frozen up. The wet dog smell is probably from the frozen coil. Plus did you happen to notice if your lines were frozen up outside when the unit was in cooling mode. Also have you changed you air filter lately, reason why I ask is a plugged filter can cause the coil to freeze up.

Customer: replied 7 years ago.

The lines didn't appear to be frozen we'll try to keep running and change the air filter. It was changed about a month ago.

Expert:  Jack Pearce replied 7 years ago.

Let me know if it gets better or not.

Customer: replied 7 years ago.

We allowed the system to continue to run. We actually remove the filter altogether and the air flow became much stronger. We purchased a new filter (though the existing filter was less than three weeks old) and that seems to have fixed it all up.