When the unit first turns on the heat strips turn on and the unit blows warm air around 90 degrees, after 15 mins or so the heat strips turn off, but the blower continues to blow air, the room is no where near setpoint, and i have checked to make sure that the thermostat is still sending the signal for heat, which it is, and i have checked the high temp bi-metal switch to make sure that it is not open, the switch is still closed,. The problem only occurs when the temp. outside is 40 degrees or colder. I have had the refrigerant checked everything seems to be up to par. why will it not continue to heat on Cold days?
An expert who has achieved level 2 by getting 100 points
An expert that got 5 achievements.
An expert whose answer got voted for 20 times.
An expert who has written 20 answers of more than 400 characters.
Re: heats for 15 - 20 mins then blows cool air
If the outdoor unit is in defrost mode the compressor will be running but the outdoor fan will not. You may even see some steam rising from the coils. This mode is to prevent frost or ice build up on the outdoor coil. Essentially it goes into cooling mode w/o the outdoor fan running.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
A heat pump on the optimal heating day (about 50 degrees ambient) will only deliver approximately 85 degree air as compared to 125 degree air from a fossil fueled furnace. The colder the outdoor air is the less heat there is available to be transferred to the living space. At 30 degrees, the heat transfer capability is getting close to negligible meaning the run cycles will be approaching continuous and eventually as the heat pump along cannot maintain setpoint, the outdoor stat or stats will bring on auxilliary heat in the air handler.
If your ambient temp is below the 'balance point' of the heat pump, the house temp will drop a little lower and most times energize the heat strips through the outdoor t-stat. Your outdoor stat could be set too low for the heat pump to carry the structure all the way down to the balance point so when you turn it off and back on, the lower indoor temp automatically brings on the heat pump plus a heat strip or two, thus the warmer air. Second stage on the stat satisfies due to the heat strip, drops them out of the circuit and the heat pump is left running on first stage heat delivering the perceived cold air.
Your outdoor stat could also be not functioning correctly and not allowing the heaters to come on until the system is turned back on reestablishing the two stage call for heat.
Tons of possibilities and not enough room to list....
It sounds like you have a heat pump. When you first turn on the system the heat strips will come on and produce warm heat (referred to as supplemental heat strips), as temperatures rise the heat strips will turn off and the "A" coil will just exchange heat to maintain temperature thus conserving energy. . Initially the temps will be around 125 degrees at the register, and drop down to about 105 after the strips turn off.
On some TXV controlled outdoor condensing units the Thermostatic Expansion Valve will stick in the cool position and require replacement this will cause this symptom. It takes several hours to do and requires a licensed technician to do as it involves recovery of refrigerants. I hope this helps
Check the following if you're unit is not giving heat. 1. Keep temp setting +8 degree from your room temp 2. Keep mode in "Heat". And check the click sound in RV when you turn to heat mode. If one failed out of three your unit will not supply heat.
Find a reputable HVAC contractor to do a
room by room analysis with heat and cooling loads calculated and units
sized and duct requirements and compare to what you have.
The air not being cold is not necessarily an indicator of anything
malfunctioning. High efficiency units for instance don't produce cold
Since you have had someone look at it, the duct
work may be collapsed which restricts air flow or uninsulated which
warms up the supply air. Either one is a possibility. Any Cox Cable guys
been stompin' around your attic lately? Wouldn't be the first time.
Usually, when the air coming out of the vents is not cold enuf it's because your freon level is low. Probably leaking, but they can usually recharge the freon and it will work for a while. Try another repair company and see if they can recheck the freon level.
We have a high efficiency unit and it produces cold air, so I don't know what previous poster is referring to. Air conditioners are supposed to blow cold air.
Sorry, to tell ya but it is normal if the outdoor temperatures are much
below 45 degrees. Below 45 degrees there is little heat outdoors for the
heat pump to grab to heat the home so it will run 24/7 and blow cool or
cold air. Below 45 the temp of the air coming out the vent will decline
and you will get no heat from the heat pump itself as you near
Your emergency heat or auxiliary heat is electric strip heat. But it
only kicks in during normal operation if the temp in the house drops 3
degrees below the setting. (some tstats if can be 5 deg.) Otherwise the
heat pump will blow cool or cold air the rest of the time if it is too
To prevent it from running all the time and blowing cold it is
recommended if the temp outside is falling below 45 degrees you should
just switch to the emergency heat setting, which shuts the pump outdoors
off, and just heat with the electric.
But if there is no heat outside the heat pumps will blow cold. They are
the cheapest and most efficient forms of heat but only as long as the
outdoor temp is above that 45 deg..
I'm guessing that if you haven't experienced this you live in some place
with moderate winter temperatures like in Northern Florida and rarely
get very cold winter temps like the freezing you have seen there
It will likely blow much warmer when the outdoor temp rises.
Hi; I hope You called a company that will honor any warranty on the heatpump. Sounds to Me like I would contact the original installer for more help or free replacement.Also at 55 or 75 degrees outside The heatpump should be providing toasty air. Only at close to freezing temps will You get a reduction in warm air and then the heat strips will help out then also check to see if the unit has outside air dampers and make sure they are closed..alpharome416
A heat pump starts losing efficiency below 30F or so. The aux. heat helps the heat pump keep up with heat demand. The Aux heat can be electric heat strips or another type of heat. Check to make sure you have power to whatever type of aux heat you have (breaker not tripped, no overloads tripped). If it is electric heat check the heat strips to make sure they haven't burnt in to. Hope this helps.
Sounds like some of the elements are not working. You being in Florida they may not have put very many elements in. It was 61 degrees last week. I know because I'm a Dolphin Fan. You will need a current sensing meter to check the elements.
If it is a heat pump, the compressor will be running both in cool mode and in normal heat mode.
Confirm the current indoor temperature. Turn the thermostat up one degree at a time until it comes on. This will typically be 1 to 4 degrees increase. As soon as it comes on stop increasing the temp.
If the compressor is running, it is a heat pump.
Check the temperature coming our of the vents at that time. You should have 30 to 60 degrees increase from the air temp going into the unit and the conditioned air temp coming out.
Then turn the T-stat up another 10 degrees. If the temp coming out of the vents increases by 20 degrees or more. the strips are on.
The strips operate in three situations.
1) the system is set to emergency heat
2) The heat pump cannot keep up with the demand for heat. (because its too cold outside, the desired temp setting is greater than 4 to 8 degrees above the room temp, or the HP is malfunctioning.)
3) The HP is in defrost mode
You could also take the panels off the unit and look for a reversing valve, but unless you know what you are looking for you will not recognise it.
Heat pumps in cold climates suffer a number of limitations stemming from the fact that they are designed for air-conditioning applications. As climates become cooler and heating becomes more of the primary HVAC function, one may find that conventional heat pumps lose capacity and do not satisfy the load of the conditioned space. In colder temperatures, a conventional system’s need to defrost can further detract from heating performance. The use of resistance heat or fossil fuels to supplement or replace the vapor cycle. The additional use of supplemental heat to temper cold air blowing into the space during defrosts. As it gets colder outside, the delivery air temperatures inside begin to fall when no supplemental heat is being used. Supply air temperatures that are warmer than the return temperatures add heat to a space, but discomfort occurs when these supply temperatures drop below skin temperature. The air movement can feel cool or even cold. While the heat pump may be operating exactly as intended,the consumer will desire a more comfortable environment.