Ask Your Question

Angie's List Answers is the trusted spot to ask home improvement and health questions and get answers from service companies, health providers and consumers. For ratings and reviews on companies in your area, search Angie's List.

Top 30 Days Experts
Rank Leader Points*
1 kstreett 240
2 Guest_9020487 110
3 Guest_9190926 105
4 GoldenKid 100
5 ahowell 95
6 KnowledgeBase 95
7 skbloom 80
8 Guest_98024861 70
9 Guest_9311297 70
10 Guest_9400529 70

*Updates every 4 hours

Browse Projects By Category

Question DetailsAsked on 4/14/2017

Home A/C unit blowing only upstairs (light air) I only have 1 unit built in 1999 until replaced about 5 years ago.

Do you have the same question? Follow this Question

2 Answers


I would look at five things if you have a multi-zone central A/C system (upstairs and downstairs get different cooling):

1) downstairs thermostat may be mis-set or has dead batteries

2) downstairs thermostat is reading cool enough because cold air is escaping from upstairs (like through open stair door) and passing over the downstairs thermostat, causing it to think the temp is right in the downstairs so it does not call for cooling

3) controller (if fancier A/C unit) or zone valve (a flapper-type splitter in the ducting which controls how much air goes upstairs and downstairs) is malfunctioning - or a control/sensor wire has broken free. (This is pretty common with solid control wiring - it can fatigue with age and crack at a connection point, sometimes staying in place but hanging on just by the insulation without the wire making contact any more). Or ifmotor operated splittear valve the control sensor or motor could be out.

4) or if airflow to upstairs and downstairs in manually controlled, the control damper might have been moved due to broken spring or someone bumped itormessed with it - pretty common if you have a child in the house who likes to fiddle with things mechanical

5) you have a refrigerant leak or similar issue causing low cooling capacity - or the evaporator coil has frozen up (or gotten clogged with lint and dust) and is no longer effectively creating cold air


If you have a mini-split unit - individual an/evaporator coil units in one or more rooms upstairs and downstairs, fed by tubing from a central A/C comporessor or heat pump - then following are common causes of your symptom:

6) the downstairs wall unit has failed - due to wiring problem or fan failure maybe

7) again - downstairs thermostat (may be on the wall unit itself) is malfunctioning, thinking that the area is cold enough when it is not


The low air flow upstairs and none downstairs - might mean (especially if A/C is in attic or upstairs) that the unit itself has a problem with fan or refrigerant level, so is only putting out a light air flow and the upstairs is the "short run" from the unit, so it is getting most or all the air. If unit is running unusually frequently or running for extended periods of time, or there is little or no cold air on the downflow side of the evaporator, turn power to the unit off so it does not burn itself out.

Depending on how good a DIY'er you are you might be able to figure it out from above - otherwise Heating and A/C is your Search the List category to find a well-rated contractor to check it out.

Answered 3 years ago by LCD



This is James in Member Care. Thanks for your interest in Angie's List!

We'll be happy to help find top rated HVAC services, but it doesn't look like you have a subscription to the List yet. You can join by visiting or by giving us a call. Our call center is available 8:00 am-9:00 pm weekdays and 8:00-5:00 pm ET on Saturdays.

Thanks for your question and we look forward to assisting you!

Answered 3 years ago by Member Services

Related Questions

Terms Of Use
Privacy Policy