I installed a digital thermostat last winter and the heat was fine. Summer came and it wouldn't cool. I switched a wire to the reversing valve and the AC was fine. Winter came again and the het wasn't working. I switched the wire back. Now the AC blows hot again. It's a single heat pump and the T-stat is a Hunter. Is there any solution?
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Re: Reversing valve wire kills either heat or AC
Your solution is throw that Hunter tsat away and get a good one. You need one with 2 stage heat 1 stage cool heat pump tstat. Heat pump tsta has w,y,o,g,w,rnad w2. Don,t buy one without this one it. I have been in this business 45 years and people are always getting sold the wrong tstat at Lowe or Home Depot. Those guys dont know jack about Tstats. Keep in touch Rus GOOD LUCK. Get the right tstat follow the letter on wiring and you wont have any problem.
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You should always include model number in requests. More info is better. In general, there is a setting for Heat and cold on cheaper thermostats. Mine is like that. It works for heating in winter and you must switch it to "cool" for summer. I assume you do have an AC unit for summer. Who wired it up? was it ever working? Did it get installed during winter? The wiring may be wrong, there are a lot of possible ways to wire. If you are not good at that (and why would you be here if you were?) better get a tech to check it out. In the old days, Edison might send out a tech for free to advise (not fix) if there is a possibility of short (dangerous).
E Back up heat/ white wire
AUX Jumper to E
Y yellow wire / Cooling - compressor
G Indoor fan Green wire
O Reversing valve energised in cooling most units Orange wire
L unknown. consult your manual Leave open
R Main power Red wire
B Reversing valve energised in Heat Rheem units only.
C Common second leg of power Blue wire.
It sounds like a stuck reversing valve stuck in heating mode based on a hot refrigerant line.
It could be stuck in the heat position because it isn't receiving 24 volts to operate, or it could be stuck internally.
Tapping on the copper tubes on the reversing valve sometimes frees one that is stuck internally. It is copper so don't get carried away or you will destroy the reversing valve.
Did you feel the temperature of both copper lines?
If the reversing valve is stuck in heat, during the winter, your heat pump will ice up, because it isn't reversing to cool as it should when it calls for the defrost cycle to occur.
Google "heat pump reversing valve" to see what one looks like
You'll need to use a voltmeter to verify that the reversing valve is receiving twenty four volts.
Pull the two wires at the reversing valve coil and check for 24 volts.
If you don't have 24 volts there when you put the unit in cooling cycle,you either have defective thermostat wiring, or a defective thermostat.
If you have 24 volts you will need to check the electrical coil that the two wires plug into.
Set the voltmeter to ohms, and make contact with the meter leads onto the terminals of the coil. One lead goes on one terminal and one lead on the other terminal at the same time, to check for continuity. You should get an ohm reading. That means the coil is good.
If the meter indicates "0" ohms the coil is shorted and needs replacement.
If the meter doesn't read any ohms at all that means that the coil is burnt out and needs replacement
When the reversing valve is activated there will be a "whoosh" sound you can clearly hear if you are near the outdoor unit.
You can order the A/C parts you need online unless you have friend that is a HVAC tech and he could get one from the Trane supply house.
It is a big job to replace the reversing valve involving freon removal and brazing. Hopefully you will find the problem in the wiring, Thermostat, or the reversing valve coil.
It sounds like either the compressor valves have failed or the rev valve has stuck in one position. You don't mention if you looked at the operating pressures of the compressor that information would help.
It may be wired incorrectly. Make sure that the compressor is being called to run when you set the ac to cool. The Green wire to T-stat makes the indoor fan run when you set the T-stat to cool...also the Yellow wire should signal the contactor to engage at the outside condenser and compressor unit. If this is a heat pump system there is usually an orange wire that will signal the reversing valve to move when cool is being called....normally the reversing valve is in the heating position in the event there is a failure to the solenoid that actuates it..thus leaving it to fail in the heat mode to provide heat in winter weather as a default. Make sure the new T-stat accomidates for your units wiring.
Red wire to R (24v supply from transformer)
Green wire to G (indoor fan)
White wire to W (call for heat)
Yellow wire to Y (call for cool)
Blue or Black wire to C (common)
Orange also to Y if not specific to t-stat (calls for reverseing valve in cooling mode)
getting heat in the cooling mode leans toward the reversing valve in the outside unit. it changes the flow of refergerint so that the hot air you get outside in the summer is blown inside in the winter. another possibility is that the reversing valve isn't getting 24v check to see if you have 24v at O and C either at the t-stat, furnace, or the outside unit. if you check at the furnace rember the safty switch for the lower door if that switch is open you will have no power. i would look at the t stat first if you have 24v there go to the outside . 24v present outside will mean a bad valve or board, no 24v means a bad or broken conection in the control wire between the stat and the outside unit(usally the orange wire)
sound like your system is under sized. for every 400 sq ft of living space you should have a ton of ac or 12000 btus. also check and see if your attic fan is working. any drafty windows or doors. your supply temp should be at least 20 deg colder then your return temp. also check your filter should be changed every three months this will help with air flow.
AIR HANDLERS DO NOT ENERGIZE REVERSING VALVE , THE THERMOSTAT DOES THE JOB THROUGH THE O OR B TERM TO THE OUTSIDE UNIT. IF YOU HOOK UP TO O TERM AND HEAT COMES ON WHEN YOU SET AC ON THEN SWITCH TO B TERM ON STAT. YOU SHOULD HAVE O TERM ON CONDENSER OUTSIDE AND YOU USE ORANGE WIRE IF YOU HAVE ONE. IF NOT USE UNUSED WIRE IN 6 WIRE STAT HARNESS.
I just had a new unit installed and I am surfing for troubleshooting tips too. My unit is doing the same... cools well heat sucks. my problem has been isolated down to the reversing valve... It is constantly energised which means it is constantly in a/c mode even when kicking on the heat strips... We disconnected a line at the thermostat and it is working well as a heater now. You may want to check yours to see if it is actually kicking over into to heat mode... -rob