During hot days when the air conditioner is on a lot it comes to a point in the evening when the air conditioner shuts down and the fan (from furnace) stays on. This will go on all night as the house gets hotter. Thermostat will be set at 72 and the temperature in the house will be 75. If I turn the thermostat up to 76 the fan will go off. If I wait a while and turn it back down past the temperature of the house the air conditioner will kick back on for a while. Shouldn’t the air conditioner stay on until the house temperature gets to the temperature off the thermostat
Fan comes on but the air conditioner does not
air-conditioningfurnace
Related Solutions
ice usually means either your air handler isn't pushing enough air across the coil, or your system is out of refrigerant.
so first step is to set the cool/off switch to off. then set your fan switch to on. if the air handler fan does not turn on, then you have a problem with your air handler or thermostat. possibly cheap. possibly something you can fix yourself.
otherwise, you probably have a problem with refrigerant (which should not deplete, and if it does then you have a leak somewhere) or your compressor. in either case, you should leave your system off to avoid damaging your compressor until someone can come out and look at it.
I think that your coils are frozen. Ironically, I had the same issue with my HVAC system last week, although I am a few hundred miles south of you. Had an A/C man come out and he taught me about how units freeze up. Here are some things to check:
1) Are your air filters clean? Dirty air filters can suffocate the system and reduce the amount of efficiency. They could also cause the unit to freeze up (Which I will get to in a moment). If your system has been run without filters or with dirty filters for an extended period, the coils could also be very dirty and you will need a professional to clean them.
2) Is your thermostat set to a reasonable cool temperature? Do you have it on AUTO or ON? Sometimes leaving it set to "ON" 24/7 can be detrimental to your systems health.
3) Would you say that your vents feel under-powered? If so, this may be another sign of the coils freezing.
4) Is your A/C Drain line free? The drain line is a small 3/4" PVC pipe that comes out of your unit and drains outside. If it gets clogged, then the natural condensation that your A/C unit generates can't be drained, and could cause the system to operate incorrectly. You can try vacuuming it with a wet/dry vac. It will let out somewhere outside your home, which is where you want to connect the vacuum. Don't use a regular household vacuum! On my unit (See picture below) there is a T joint and a cleanout, so I didn't have to cut my line. I was able to pour water through it with a funnel to verify that it was not clogged.
Touch the insulated refrigerant line. You should see it uncovered right next to the indoor unit). It should be very cool to the touch. If it is only slightly cool after several minutes of running the outdoor unit, then you are probably low on refrigerant.
Is the air sufficiently cooled? Get a thermometer and measure the temperature of the air as close to the unit as you can. In my case there is an intake a few feet from it, so I measured the temp in the duct. Then, measure the temperature in a outgoing vent. The difference should be about 20 degrees (F). If it's less (it was about 11 for me), then you may not have enough refrigerant in your lines.
So here is something to try: Turn OFF your A/C, and run the fan only. So turn your thermostat to OFF and the fan to ON (not auto). This will help defrost the coils. After about 4 hours, cut on the air again. Does the air feel significantly cooler and at a better air flow rate? This may indicate that the coils did in fact freeze.
When your coils freeze, it reduces airflow. The outside unit keeps pumping cold refrigerant through the system, thus making the problem worse. Sometimes the ice will make the air feel very humid, but because only a small amount of air can go through, the house will not cool.
It's okay if your coils freeze up once in a blue moon, (once or twice a year). But, if you are having to defrost every day like I was, then you need to call a repairman. You likely have a refrigerant leak. This is nothing to panic over - it's not like Carbon Monoxide or anything, but, it means that your system is burning electricity like no tomorrow ($$$) and you are still cooking in your own castle.
The repairman will assess if you have a leak and what your pressure is and should be at. He will refill your lines (and replace them if he needs to). While the bill will be high, I ended up saving $200 a month on my power bill after he came out (House went from 4000kwh to 1200kwh).
Note: Don't try to recharge the A/C refrigerant with an OTC kit, there are multiple kinds of refrigerant, and you should never mix them. A professional can properly assess what kind of refrigerant you need, if there is a leak, and what your options are to fix it.
Good Luck!
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Best Answer
There are a lot of possible reasons this could be happening, but here are some common ones:
1. Frozen coils
If too much moisture remains inside the indoor unit, it can freeze and form big blocks of ice around the refrigerant coils. Instead of cooling the air, the refrigerant just keeps making more ice.
There are several common reasons for icing, especially if the unit has been running for a long period of time:
1a. Icing due to clogged drain
If the condensate drain out of the unit is clogged, the backed up water causes elevated moisture levels in the air inside the unit which form ice on the coil. As more water sitting in the drain pan evaporates, the ice gets thicker.
Find the condensate drain from the indoor unit and check it. How to do this will vary depending on your unit.
1b. Icing due to poor airflow
This is most commonly seen on units with very dirty air filters. The airflow through the filter is restricted, meaning that not enough air is flowing through the coils. As above, the moisture condensed on the coils freezes. It can also happen if the return vents are blocked by items in the house.
2. Failing capacitor
Inside the outdoor unit of your air conditioner, there is a large capacitor that is used for starting the unit. If this capacitor fails, the outdoor unit won't run and the refrigerant won't circulate. Make sure the thermostat is calling for AC (turn it really low) and go outside and see if the fan and compressor are running. If they are not, listen closely to see if you hear a faint humming noise. If you hear the hum, you need a capacitor.
3. Low refrigerant
You probably need to get an HVAC professional to check this one - they have special tools to measure the refrigerant flow through the system.