# Is it time to call A/C guy (central air question) **URL:** \ **Category:** In My Humble Opinion\ **Created:** [September 3, 2015, 9:38am UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801 "2015-09-03T09:38:18Z")\ **Posts on this page:** 12\ **Page:** 2
**Author:** ![Infovore](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/infovore/32/420_2.png) [@Infovore](https://boards.straightdope.com/u/Infovore)\ **Post date:** [September 7, 2015, 10:34am UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/21 "2015-09-07T10:34:32Z")
> [@diggerwam](#): > > Yep, we have a big old ice cube on our a/c bits. I’m in the process of trying to melt it nice and slowly. > > Bigger question - why did it form and how do I stop it from happening again? Is something wrong with the a/c? According to the guy we talked to, it was caused by not changing the filter. Our filter was a mess, completely clogged with dust. We hadn’t changed it in a long time. When it gets clogged, the AC has to work a lot harder because it can’t “breathe.” ---
**Author:** ![diggerwam](https://avatars.discourse-cdn.com/v4/letter/d/919ad9/32.png) [@diggerwam](https://boards.straightdope.com/u/diggerwam)\ **Post date:** [September 7, 2015, 9:48pm UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/22 "2015-09-07T21:48:00Z")
Confused, are you talking about furnace filter or talking about a filter in the central a/c unit. If in a/c unit, where is it? ---
**Author:** ![Infovore](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/infovore/32/420_2.png) [@Infovore](https://boards.straightdope.com/u/Infovore)\ **Post date:** [September 7, 2015, 10:08pm UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/23 "2015-09-07T22:08:15Z")
> [@diggerwam](#): > > Confused, are you talking about furnace filter or talking about a filter in the central a/c unit. If in a/c unit, where is it? I’m not sure what they’re called. There’s a filter in the furnace–I’m not referring to that one. We have two of the other kind: one downstairs and one on the stair landing, both down fairly close to the ground behind fairly large metal covers. They’re not in the actual outdoor unit, but inside the house. I think the structure is called a “[return](http://www.wisegeek.org/what-is-a-return-vent.htm)”–the two of them we have have big open pipes behind the filter, where the air gets sucked in to be recirculated. ---
**Author:** ![zuer-coli](https://avatars.discourse-cdn.com/v4/letter/z/ba9def/32.png) [@zuer-coli](https://boards.straightdope.com/u/zuer-coli)\ **Post date:** [September 8, 2015, 11:33pm UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/24 "2015-09-08T23:33:31Z")
An iced up indoor coil indicates the following: The uit is low on refrigerant, or the air flow is insufficient. With a A/C unit that is one year old, a leak could result from poor installation practices or much less likely a factory leak. In either of these cases the installing Contractor should stand behind the product and his/her installation. You don’t say if your indoor fan seems to be running or not but if you have a big block of ice air will not flow anyway. I would check the indoor filter and if possible the indoor fan. the fan should run\* and the filters should be reasonably clean. As mentioned up thread there are many online resources, some of which are suitable for non-specialists in Refrigeration. (FWIW A/C is a Refrigeration application, systems have the same principals and same basic components; Evaporator, Condenser, metering device and method of creating a pressure difference, ie Compressor.) - I don’t know your level of experience and hesitate to attempt to advise you as to how to tell if the indoor fan is running, the internet is a useful source of information, search for function of A/C and furnace, I am assuming that is your set-up. best of luck. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [September 8, 2015, 11:54pm UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/25 "2015-09-08T23:54:33Z")
> [@zuer-coli](#): > > - I don’t know your level of experience and hesitate to attempt to advise you as to how to tell if the indoor fan is running, . Why shouldn’t he or she hear it, or feel some movement of air? ---
**Author:** ![I.Dunno](https://avatars.discourse-cdn.com/v4/letter/i/9f8e36/32.png) [@I.Dunno](https://boards.straightdope.com/u/I.Dunno)\ **Post date:** [September 9, 2015, 2:27am UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/26 "2015-09-09T02:27:35Z")
> [@carnivorousplant](#): > > Why shouldn’t he or she hear it, or feel some movement of air? I’m a retired HVAC tech (mostly commercial but I can work on residential too) and I can’t tell you how many times I’ve tried to help someone (phone, text, etc.) without being there, and getting completely wrong info from the “customer”. And I also don’t want someone who doesn’t know what he/she is doing, to get hurt or worse by my asking them to check something. Even with the guys I worked with, I would prefer to see the problem myself rather than rely on someone else’s word. I just helped out my brother with “not cooling, it must be low.” Pressures WERE low but, his coil, (in a hot attic space hard to get to) was partly iced over. Thawed it out, now working properly. I’m not sure what the problem was. I know he has experimented with pleated filters and that DID ice his coil once before. And I now know that he severely oversized this unit (one of two in the house) when he put it in several years ago. Like said above, low on charge, stopped up filter or coil, fan not running or running on the wrong speed are the most common causes of a frozen coil. The OP has a relatively new unit, the installer should be called and he should stand by his work. ---
**Author:** ![I.Dunno](https://avatars.discourse-cdn.com/v4/letter/i/9f8e36/32.png) [@I.Dunno](https://boards.straightdope.com/u/I.Dunno)\ **Post date:** [September 9, 2015, 2:33am UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/27 "2015-09-09T02:33:13Z")
> [@carnivorousplant](#): > > Why shouldn’t he or she hear it, or feel some movement of air? I just realized I should have answered your specific question better than I did. Sorry. If the coil is iced completely, there will be no airflow to feel or hear. And if the unit is in a remote location, it may not be easy to tell if the fan is running by listening. Ideally, you could open the air handler door and carefully look. But that is not always easy to do. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [September 9, 2015, 2:49am UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/28 "2015-09-09T02:49:51Z")
> [@I.Dunno](#): > > Even with the guys I worked with, I would prefer to see the problem myself rather than rely on someone else’s word. > The OP has a relatively new unit, the installer should be called and he should stand by his work. I feel the same with computer network problems. Yes, new installations should be fixed by the installer. ---
**Author:** ![Motorgirl](https://avatars.discourse-cdn.com/v4/letter/m/e36b37/32.png) [@Motorgirl](https://boards.straightdope.com/u/Motorgirl)\ **Post date:** [September 9, 2015, 4:49pm UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/29 "2015-09-09T16:49:20Z")
> [@I.Dunno](#): > > I just realized I should have answered your specific question better than I did. Sorry. > > If the coil is iced completely, there will be no airflow to feel or hear. > > And if the unit is in a remote location, it may not be easy to tell if the fan is running by listening. Ideally, you could open the air handler door and carefully look. But that is not always easy to do. During a marathon phone-based diagnosis this summer, my HVAC guy had me tie a very light ribbon to one of the registers (vents? where the air comes out). Fluttering = my fan is moving air. I used some Christmas ribbon. ---
**Author:** ![Motorgirl](https://avatars.discourse-cdn.com/v4/letter/m/e36b37/32.png) [@Motorgirl](https://boards.straightdope.com/u/Motorgirl)\ **Post date:** [September 9, 2015, 4:55pm UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/30 "2015-09-09T16:55:39Z")
> [@Motorgirl](#): > > During a marathon phone-based diagnosis this summer, my HVAC guy had me tie a very light ribbon to one of the registers (vents? where the air comes out). Fluttering = my fan is moving air. I used some Christmas ribbon. Missed the edit window. Our icing problem was caused by low refrigerant, which he recharged and gave us instructions for how to keep an eye on it so we know how fast it’s leaking. But our system is about 11 years old. I’d be pretty alarmed/annoyed by a one-year-old system leaking refrigerant. Some other things he had us try before coming over (he’s a friend and neighbor so he goes a bit above and beyond for us before doing something that will cost us money): - cleaning the outdoor unit (it had some grass in it from the lawn mower - changing the filters at the intake/return locations - trying various on/off settings for the condenser and fan to see when the ice started reforming and cleared He also cleared the pipes that drain water from the condenser as basic maintenance but the culprit was low refrigerant ---
**Author:** ![VinylTurnip](https://avatars.discourse-cdn.com/v4/letter/v/b2d939/32.png) [@VinylTurnip](https://boards.straightdope.com/u/VinylTurnip)\ **Post date:** [September 9, 2015, 6:02pm UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/31 "2015-09-09T18:02:47Z")
> [@Motorgirl](#): > > He also cleared the pipes that drain water from the condenser as basic maintenance This, as I learned yesterday, is a good idea. Our 2-year-old A/C system gave out a few days ago, and it turned out that the condensate drain pipe had clogged which caused water to pool inside the furnace until it dripped onto the circuit board. Luckily it was under warranty in our case, but it required replacing the control board. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [September 9, 2015, 10:57pm UTC](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801/32 "2015-09-09T22:57:59Z")
> [@Stink Fish Pot](#): > > I called the A/C installer and he said that the air temp coming out if the vents should be about 15 degrees cooler than the setting. That’s his rule of thumb. > > So, if you have the thermostat set to 72 degrees F, the air should be coming out at about 57 degrees. > > No idea if this is true, however. I tested mine, and it’s about 10 degrees cooler than the thermostat. > > Better call that guy and get his ass back over here. Worry about rule of thumb guys. Check the return air temp and the discharge air temp nearest the indoor fan unit. 15 to 20 degrees is normal. [Previous page](https://boards.straightdope.com/t/is-it-time-to-call-a-c-guy-central-air-question/729801.md?page=1)