Why Is My Heater Blowing Cold Air?

​Yikes! If you suddenly notice the unpleasant surprise of your cold air coming out of your vents, several things may be happening to your heater to cause this strange phenomenon all centered on a “RESTRICTION” theme. First, shut your heater and fan to the off position on your thermostat, because if your vents are blowing hot air, continuing to run your heater will only continue the problem. This post will explain what causes cold air to come out of the vents when you have your heater on, when warm air should be coming out instead.

Where do restrictions come from?
(STOP AND DO THIS EASY FIX FIRST)

1. Restrictions can come from several places in a heater; one of the most common restrictions is from a dirty filter.  It may seem over simplified, but check your air filters and see if it’s dirty. If it needs to be changed, put a clean one in before you do anything else. Dirty air filters can actually reduce the airflow into the heater enough to freeze the coils and put the heater into defrost mode so you want to be sure they are changed out regularly.  We recommend the 4” HEPA filters first, and then the cheap 30 day filters second and LASTLY the 1” pleated filter (booo)!
2. If you have an older gas furnace, check that the pilot light hasn’t gone out. Constantly having to re-light your pilot light is not normal and a health and safety hazard, and your heating system and flue assembly should be inspected.
3. Once you have changed your filter, check that all the supply and return grilles are not blocked and completely open. The second type of restriction can come from blocked vents. I know the registers and grilles aren’t the prettiest things to look at, but don’t cover them with dressers or bookshelves if they are on the wall or the floor.  You need at least a foot of clearance for proper airflow around each vent.
4. Another type of restriction can occur in the filter dryer. The filter dryer’s purpose is to catch contaminants from entering the compressor. If too many contaminants become caught in the filter medium, it can become clogged just like your air filters and restrict the flow of refrigerant to the compressor. 
5. Dirty evaporator coils can also cause low airflow restrictions. If the filters have not been regularly changed, that dust that should be caught by the filter may have gotten past the filter and ended up on the coils, further clogging the system.  A regular cleaning of the indoor coil and sealing the ductwork can go a long way in having a problem-free heater and air conditioning system.

Other Reasons Why Cold Air Is Blowing Out Of Your Vents

Besides restrictions in all its forms, cold air may be blowing out of the vents due to other reasons as well.

1. Wiring or control board related. Loose wires or improper wiring can trick your heater to thinking it’s an air conditioner. A Green ID technician will be able to diagnose exactly where the problem is coming from and make the appropriate repairs. 
2. Low refrigerant. Heat pumps are never supposed to lose refrigerant. If your system is suddenly low on refrigerant, it likely has a leak that should be repaired.  Adding more refrigerant always guarantees you’ll have another call heater or air conditioning problem down the road. 
3. Blower speed is set too low. Not having enough airflow over the coils can also cause a lack of heat transfer and drop the Freon temperature below freezing, which can start ice blocks to form over the refrigerant lines and coils.  

​What Are The Symptoms?

1. Obviously having cold air blowing out of your vents
2. Ice forming on your refrigerant coils 
3. The home is not warming up to the thermostat set point during the winter season

If you experience any of these symptoms remember to first check and change your air filters, then call Green ID at (602) 926-1650 and get your AC repaired today. Mention this blog to get a free trip charge and 5% off any repair.