Question about Heating & Cooling

1 Answer

Reversing valve wire kills either heat or AC

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?

Posted by on


1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 614 Answers

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.

Posted on Nov 20, 2009


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

2 Answers

I have the 5 day. 2 day programmable thermostat. Installed in the winter but now that it is summer air conditioner won't come on. Can you please advise?

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).

May 20, 2017 | Heating & Cooling

1 Answer

How do you relpace an A.C. thermostat?

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.

Aug 30, 2014 | Honeywell RTH3100C - Digital Heat Pump...

1 Answer

Why does it shut off after it starts ? 2a6b3060a1000a american standard

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.

May 16, 2014 | American Standard Heating & Cooling

1 Answer

Nordyne heat pump

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.

Jun 12, 2013 | Heating & Cooling

1 Answer

I switched my thermostat to save money but now it is 85 in my house and it constantly is running but it is hot all the time my dad put it in so i know its right what is wrong with it

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)

Oct 13, 2010 | Heating & Cooling

1 Answer

Heat comes on when the temperature setting calls for cool.

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)

Jul 10, 2010 | Carrier Heating & Cooling

2 Answers

A/C does not cool like it used to, unit runs

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.

Jun 07, 2010 | Carrier 38CKC042 Air Conditioner

2 Answers

Change out problem


Apr 21, 2010 | Heating & Cooling

1 Answer

Honeywell Wireless System THM5320R Wireless system and thermostat startup ok. The issue I am having is that; when the thermostat is in cooling mode and the unit starts the reversing valve is in the wrong...

how old is the existing system? i do ac in florida and usually if its not the wiring, an old systems rev. valve may stick. a firm tap on the valve may solve your problem.

Oct 28, 2009 | Heating & Cooling

2 Answers

Goodman ac / heat pump

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

Nov 25, 2007 | Goodman CLQ36AR49 Air Conditioner

Not finding what you are looking for?
Heating & Cooling Logo

Related Topics:

149 people viewed this question

Ask a Question

Usually answered in minutes!

Top Heating & Cooling Experts


Level 3 Expert

2515 Answers

Dan Webster
Dan Webster

Level 3 Expert

8220 Answers

Donni Steen

Level 3 Expert

659 Answers

Are you a Heating and Cooling Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides