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Emergency Heat only & no air conditioning

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Old 03-16-2006, 12:09 PM
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Default Emergency Heat only & no air conditioning

Hi, I live in a condo and part of my heat/cool system is on the roof and part is in my shed closet. The system is electric. For the past month my system has been heating on 'Emergency Heat' only. I switched it to air conditioning the other day to test it, and only heated air came out even though the display said "cool". I'm having someone come out this weekend to look at it, but does anyone know what this is a symptom of ? Am I looking at a hundred bucks for a new thermostat or thousands of dollars for a system replacement or something ? Any advice will be appreciated. Thank you for your time.

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Old 03-16-2006, 03:48 PM
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Default RE: Emergency Heat only & no air conditioning

I did heating and cooling work for 12yrs.

What you have is a typical Split System. Either a heat pump or just a simple air handler with toaster coils inside.

On a heat pump:
It is basically an air conditioner (AC) An AC works by compressing vaporized freon gas into a liquid and then pushing it through a small orifice or atomizer. Freon has a unique quality (well, not totally unique--most vapors will get cold when they expand--but freon does it really effieciently) , in that it gets cold when it expands. Push compressed, liquid freon through a small orifice and let it expand inside an evaporator coil (radiator)--and it gets cold. Blow air over it. Cold air. The radiator absorbs heat from the ambient air. Transfers the heat into the freon. Takes the hot freon back outside, in vapor form, and then uses a condenser fan and another coil to blow the heat away from the condenser coils. This cools the hot vapor before it gets pushed back to the compressor for another compression into liquid state and a trip back through the coil inside.

During the heat phase--the flow of freon direction is reversed. It takes any amount of heat outside, from the condenser coils, and pushes the freon inside. The blower motor inside the house takes the heat from the freon as it travels through the evaporator coil, and the freon gets sent back outside for another trip through the compressor.

This is a shot in the dark, but there is a solenoid valve that switches the direction of freon through the system. This is only applicable to the heat pump system. If the solenoid valve is faulty, if could be locked in the "heat" side. You will only get heat from the system because the freon is only flowing in the direction required for heat function. It can't flow the right way for cooling to take place.

If you DO have a heat pump system, it could be a simple solenoid valve. $150 to replace it.


If you can give me some more details, I might be able to help.

What brand?
Model number?
Is the T-stat programmable/digital--or old manual type?
How many wires are connected to the BACK of the T-stat? Colors? What terminal is each wire attached too?

Just pull the front cover off the T-stat and look. You might have to pull a couple screws and pull the whole unit off the wall, but thats no big deal. Don't worry--you can't get shocked, and you won't damage it by taking it off the wall. You CAN get shocked-but you'd have to really work at it. It's only 24V anyway. Just tingles a bit. Just don't touch the bare wires. No big deal.

Go up on the roof. Shut it down. There should be a disconnect box or a main circuit breaker. Shut it down. There's 220V inside there. It WILL shock you and it ain't gonna be a little tingle. It'll knock you on your butt and put you in the hospital if your lucky--kill you if your not lucky.

Remove the access panel on the unit. Look for a RESET button. If it has one--PUSH IT. Put the access panel back on and turn the power back on.

Pictures help. Take a pic of the back of the T-stat. Take a pic of the circuit board inside the unit when you pull the access panel off. Take pics of ANYTHING thats got wires going to it. That will help a bunch. If I can't help you--I got friends who might be able to. But, I really need some pics of the wiring and circuit boards.
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Old 03-17-2006, 12:27 AM
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Default RE: Emergency Heat only & no air conditioning

I believe the "Emergency Heat" is a toaster coil, sort of a back up system if the heat pump should fail. When you say "Emergency Heat" only I guess you can't get any warmer than usual heating? Maybe the heat pump really failed too.

If it still heats when the system is set to "Cool", check if you're in "Dehumidifier" mode. Dehumidification is done by the cooling coil condensing the water vapour in the air and then heat it up again, so if the cooling coil isn't working you got heat only (if the toaster coil is not regulated by the T-stat and let to run). See if there's one and whether you can control it. Maybe the refrigerant "Freon" escaped through a leak in the coils.

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Old 03-18-2006, 10:12 AM
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Default RE: Emergency Heat only & no air conditioning

Hi guys, Sorry I didn;t reply earlier but I was real busy in the office and didn;t get to check. RCpilet, thank you for taking such great interest in my dilemma. Your offer of diagnosing and looking at pictures was a really kind thing to offer, and I thank you. The guy came this morning and said something about reversing valve not getting energized. He reprogrammed something and the unit seems to be operating normally now. Thank you for the advice guys, it was greatly appreciated !

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Old 03-19-2006, 07:06 PM
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Default RE: Emergency Heat only & no air conditioning

Quote:
ORIGINAL: Ramones The

Hi guys, Sorry I didn;t reply earlier but I was real busy in the office and didn;t get to check. RCpilet, thank you for taking such great interest in my dilemma. Your offer of diagnosing and looking at pictures was a really kind thing to offer, and I thank you. The guy came this morning and said something about reversing valve not getting energized. He reprogrammed something and the unit seems to be operating normally now. Thank you for the advice guys, it was greatly appreciated !

Ramone
Quote:
This is a shot in the dark, but there is a solenoid valve that switches the direction of freon through the system. This is only applicable to the heat pump system. If the solenoid valve is faulty, if could be locked in the "heat" side. You will only get heat from the system because the freon is only flowing in the direction required for heat function. It can't flow the right way for cooling to take place.

I do get lucky once in awhile. [sm=thumbup.gif] I kinda figured since you were on the east coast and had a split system that you had a heat pump. The reversing solenoid valve is a common problem.
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Old 03-21-2006, 11:03 AM
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Default RE: Emergency Heat only & no air conditioning

Yep, you hit the nail on the head. As he was telling me, I felt kind of relieved that I had heard it from you first. So I just had to pay for the visit and luckily no parts or anything. He just repogrammed my thermostat, and showed me what he did in the instruction manual.

Thanks again !! Ramone
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