Trane AC not cooling after being turned to heat mode for a couple days

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Jun 5, 2014
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Last week we had some freezing temps (unusual for our area and even more unusual this time of year). My elderly mother can't stand cold so she turned the heat on but when the weather warmed up a bit more it won't cool anymore. It heated above the level it was supposed to heat to and now it won't cool off. The house is much warmer than the outside. It's like the thermostat is not communicating properly.

I read that the fan will only make things hotter if the coils are still warm/hot and it will only circulate hot air so my 3rd step (1st step was switching to Auto, 2nd to Cool-- to no avail) was to hit the button to turn the fan off. It didn't work. Fan would not turn off even after I left it for several minutes. I mashed the button multiple times and the only thing that changed was the display. I flipped the breaker on and off in the hopes it might reset things. Nope. I eventually just turned the whole thing to Off. Which did seem to work as far as I could tell. I checked the filters, poured bleach down the condensate line, capped it back up tight, played with the settings on the thermostat-- only thing that seemed to work was turning it off and when I turned it back on the fan came on (even when set to off).

I decided to pull the cover but apparently this thermostat has the entire kit and kaboodle attached to the cover and there is a wall plate with wires that stays on the wall when it is pulled off. It has 7 wires. I traced the wire from mid-level on the furnace up to the ceiling, down the wall, and into a hole near the thermostat. I took pictures and then popped it back on. After that the fan will turn on and off when I push the button but nothing seemed to happen when I switched between heat, cool, and emergency heat modes. Only thing that worked was "off". I currently have it set to cool, but last I checked its still at 87°F and highest it is supposed to allow is 72°.

The outside compressor is not kicking on so I don't know if it blue a capacitor again (we just replaced both capacitors AND the fan motor a few months back) or if there's something wrong with the thermostat. It's over 10 years old. I think we had it installed in 2009 or 2010.

I really hate this thermostat because it is hard to see unless you are at just the right angle and have enough light and even then, some of the writing is too small for me to read without glasses. When I first popped it back on, it went to EMHeat. When I saw this in the picture, I switched to Cool.
It looks like there may be 2 separate cables so I'm assuming some are coming in from the furnace and others are going back out to the compressor? I'm not overly familiar with this stuff. The bracket off to the right on the wall part holds some sort of clear plastic piece with a tab (I didn't take pics) and I'm not sure what it is for. It can be pulled out from the right side.

Any thoughts? I want to replace it with something that I can see more easily and that has good controls.
It's now up to 88. It's 74 and raining outside.
My local electric company mailed us out free digital thermostats, but I don't know if they work for heat pumps systems...
Can you shut down your main breaker to the furnace? It is also possible that your thermostat is bad, a wire was eaten by a mouse or rat, or your mother board on your furnace is fried.
I shut off the main breaker- wasn't able to see the temperature that way. I noticed that when the fan is off it started to cool a little but my brother kept turning the fan back on and it got hotter again. It's down to 81 now. 70 outside. I have windows open to let hot air out and cool air in. I'm going to see what happens when I shut the breaker off for longer. Friend is coming out to troubleshoot later today. He's not an Hvac person but he is good at figuring things out. Need to get a ladder and take that panel off (it's in a raised cubby so it requires a ladder or some sort of stepstool to access.
Other than the spider sac, the thermostat itself looks good. I traced the wire back so I know where it goes in to the furnace. Probably full of bugs/spiders inside.

I do ultimately want a better thermostat that has an easier to read display. I wouldn't mind one that let me see the temperature from my computer or phone so I don't have to go look at it physically. Not sure if I'd want remote control of it bc I'm sure my brother would be changing settings.
IF the thermostat is an issue, I'm thinking of getting this one but it only has 5 wires although it has ports for more.
This is the wiring diagram for it:
On mine, I can't read what the black wire is going to. R is red, ? Black (looks like it might be Y something), W is white, Y is yellow, G is off white, O is orange, and B is blue.
Any thoughts? Or should this be in electrical forum?
The only way to confirm is to go to the other end and copy your color wires and match them to your furnace. Sometime a pic from a phone camera will help. That is where a specialist would be worth their weight in gold.
My friend found more wiring diagrams in the pdf and did his best to match it. New thermostat is in and temp is down to 77. But it was down to 80 before. Compressor wasn't kicking on. My room is nice and cool because my window is open. Hopefully this will solve the issue, but not sure if something went wrong with the compressor. If this doesn't work at least we have a really nice new thermostat with big letters that I can read without the overhead light on or having to use a flashlight.

My brother just came out and looked at it. He likes the way it looks. I need to get the model numbers for my furnace and the compressor and make sure everything is wired properly. The black wire looked like it went to W1/X2. I can always contact Honeywell to ask them for assistance on the wiring if things don't work. It might just be too cold outside for the compressor to kick in. It was 80 when my friend installed the new thermostat about 45min ago. Not sure if the cooling is bc its 57° outside and windows are open or if its bc it's actually cooling off.
If you have a heat pump you will need to get a @ Stage thermostat for the nit to work properly.

You picture of the old thermostat does not show to be a 2 state thermostat either? Has it ever work properly since your last repair?

The stat should have switch that says : Cool, Heat, Emergency heat
I have a nest thermostat for my heat pump. I love it. I can control it from work, set it for both heat and cool etc. The w2/x2 are your e-heat i believe, from what I remember with mine.

Is it running any better? Was the new thermostat specifically for heat pumps?
The new thermostat works with heat pumps. It does have options for heating, cooling, and emergency heat. It also has settings for the fan. We set it to 72 and "permanent" and it has been holding at that consistently ever since. It can have different settings at different time of the day or different days of the week but I have not messed with any of that. My friend was going to name it something funny but the name was too long. So, it is just on our devices as HVAC. If we want to connect to it wirelessly, we can. It's like our printer now.

TL: DR? New one is working great!
I spoke too soon. It seemed to be working but I think it was because I opened windows and let cool air in. It is holding at 76 (still better than in the 80s) and I turned the temp down to 68 to see if it would cool. It is on cool mode. Compressor hasn't made a sound since the initial problem so I think it may be something on the outside unit having an issue. I need to cut the weeds in the yard before I can have someone come look at it though.
1.Does it have good airflow around the u it? Like no weeds or anything within 5 to 10 feet of the unit?
2. Have you checked how all the vents are attatched inside? Made sure they were secure and not loose
3. Had someone get under the house to make sure the ductwork is intact?

You may have already addressed this, and if you have I apologize..

Hopefully you get it figured out soon
1. It has weeds around it but it can still get good airflow-- the compressor isn't even trying to kick on and it had been running fine. Usually if it has a problem with getting choked out by weeds the capacitors blew (and that was visible).
2 & 3. Vents are in the attic and all appear to be connected. All of the ceiling vent thingies are getting airflow. The internal fan is running, but the external unit is not turning on.

My sister had the reverse problem where heat would not come on and it would only blow cold. She said there was an electronic switch outside that wasn't working. So, I need to find the specs for this thing. It could be a switch, could be a compressor. Mild possibility that its the capacitor(s). But I will have to clear the weeds. I need to charge my jawsaw for the thicker weeds.
I'm glad your vents aren't in the floor. Mine are. I had them all replaced 4 or 5 years ago ($3500 for everything from unit to vents) and my moms cats peed in a couple of them. Thats near impossible to clean. Thats another story for a different day.
I'm glad mine aren't in the floor either. We had floor vents in our house in Virginia. We used to call down through vents to the basement.
So, we FINALLY got an AC repair guy out. He cleaned up a spot and found the model number tag inside. It's Trane Air Handler 4TWB3060A1000BA. He confirmed that the compressor is bad. He said it would be more efficient to get a whole new air handler that is compatible with the inside unit. I can't even find a replacement compressor for that unit so it may be the only option. I'm trying to figure out how to determine what air handler is compatible with that inside unit. He said he has a different brand that will work, but I wish I could find more info. I don't even know where to look.

The inside unit is Trane 4TEC3F60B1000AA.

Label on outside unit: I believe its XB13. I was having trouble with blackberry vines trying to get this pic.

Label on inside unit:
Any ideas?
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First thing to check is the relay that's inside the outside unit. You will have a power shutoff-probably on the wall of the house carrying power to the unit. It will have 220VAC with a connection to the relay inside the unit. That relay can fail to switch power to the compressor. I had to replace the relay in mine just last season. The relay was about 40 bucks. You can use a voltmeter to see if the compressor gets power when the thermostat calls for it.
To clarify: An AC repairman came out to check. The connections are all good, but he determined the compressor is dead. These compressors only last around 10 years. This unit was made in 2009 and we had it installed in 2010.

I asked Trane for info and this was the reply:
So much for "customer" service. All I needed was the info to be able to order the right units.

I found that the only Trane dealer in the area is over an hour 30 min away and they don't install out in my area but they said they can sell me either the compressor or the condenser. I left my contact info and the lady said they would call me back once they had specific prices and info. Said they could sell me a non-returnable compressor and someone else would have to install it. Also said they could sell me a whole new condenser unit. They will have info sometime next week. If they can't reach me by phone they will text me.

I'm hoping we won't have to replace the inside unit as well, but we may have to in order to have compatible units. Maybe we can get something more efficient.
Don't know who your 'AC Repairman' was.. but it's really EASY to 'decide' that the compressor is bad .. when it's really NOT .. it's just the relay. Depends on how much you trust your repairman .. and I WATCH any repairman that works on any of my equipment. I can tell if they checked that relay first before deciding that the compressor was bad. Relay = EASY & CHEAP... compressor=NOT EASY & VERY EXPENSIVE .. and generally means almost as cheap to replace EVERYTHING ($6K to $10K). I hope I don't jinx myself, but MY heat pump almost 20 years old and works just fine... but it did need that relay replaced last year.

Worth checking .. or even CHANGING that relay first if you're not sure, but if you HAVE a voltmeter and can read it, then it's easy to tell. If you're at all 'handy' and don't HAVE a voltmeter (multimeter usually), it's a fantastic tool to have at hand. The list of things you can check (and DECIDE what needs to be FIXED) with just a multimeter is almost limitless.