Home HVAC Errors Are Hard to Diagnose Without a Tech

“I’ve been having this issue with this Honeywell thermostat for our upstairs thermostat only. when using the smart app for temperature control, the system works perfectly and will set any temperature I need and blow seemingly cool air. Lately, the touch screen on the physical thermostat will stop working and the time listed is off. when I take the faceplate off the wall and reconnect, it works sometimes and resets, while other times it says “power down thermostat for 1 hour”. The thermostat does”

“Hi HVAC wizards! Need help to configure this thermostat, I searched for hours couldn't find any manual It's stuck on sleeping mode and timers no idea where to find user guide Appreciate anyone can help me please Thanks submitted by /u/be5be5Man [link] [comments]”

“Can someone please help? I’m at a loss and have retried setup multiple times. I plugged the nest into usb to ensure the device works but can’t get power to work. My old stat was a Honeywell home and had batteries but still had a common wire, so I think it was still getting power? Attaching pic of old wiring and current wiring. submitted by /u/italianova [link] [comments]”

“Hello, I'm a newish homeowner and had a hisense heat pump with central air installed in Dec 2023. The fusible link for the backup heat blew out due to a clogged filter. The filter was replaced, but the fusible link is still out. How difficult is this to replace? It's high voltage correct? I know I'd turn off the breaker etc, but is it also difficult to find and remove the old and replace with the new? The HVAC company gave a pretty high quote so I could also shop around. submit”

“Google Nest Thermostat…. Yea, it only gets better… Two transformer system. Air handler works fine but boiler zone valve won’t open….yea….I open the stat and discover speaker wire on RH and W….2nd floor and the wall cavity is over a stairwell. Yup submitted by /u/AwwwComeOnLOU [link] [comments]”

“Noticed my thermostat stopped working and kind of stumped, I would appreciate any advice. Here’s some background: -Had a power outage yesterday that lasted 30 minutes while I was at work -Noticed today that the thermostat is not working, removed it and checked for voltage between A and B, 0V reading. Also verified no short between the thermostat wires. -the three fuses that I located are in good shape, and continuity checks good on each. -float switch in pan not contaminated, read closed 0 ohms”

A recent development in my house is that the fan stopped being able to run on its own. Ecobee thermostat was supposed to run it 5 minutes an hour. I noticed it…

“Good mornings HVAC folks. I have a Ruud/Rheem high efficiency furnace and when we tried to turn it on for the first time this morning, we got an error 57. A quick inspection of the vent outside showed it was completely blocked with a paper wasp nest and some pretty angry wasps. I didn't have time to deal with clearing that out this morning (it's now a problem for future u/Senior_Cheesecake155 ). BUT, once I do get it cleaned out, I'd like to take measures to prevent this from happeni”

“During the last days of last winter, woke up to find it very warm in the house. Thermostat was supposed to be set to 72 F but it was 80'ish. I'm thinking it's a stuck relay or contactor on the furnace control board, causing the furnace to ignore the thermostat's shutoff command. I just shut it off as it wasn't necessarily... but winter is just around the corner and I need to fix this. Anyone else deal with this problem? submitted by /u/Key_Lifeguard_8659 [link] &#”

“I can't figure out this thermostat for my life. I live in a condo rental and I'm trying to set the temperate to be 72°F all day. However, the A/C keeps turning on at the most specific time of the day and then the temperature drops to 65°F. For some reason, always at 10:38 AM the A/C will turn on and the temperature starts dropping unless I go and set it manually to be 72°F again. It turns on again later in the day but I don't remember which time exactly. How do I make this specific t”

“I recently experienced a problem with my electric heat pump where the house temperature exceeded the thermostat cooling setting by 3 degrees. The condenser was running but the air handler was not. I shut the unit off at the thermostat and went to bed. The next day after returning from a morning appointment I turned the system on via the thermostat and it has been working fine for almost a week. My question is, is there a smart thermostat available that could be programmed to handle that situatio”

“https://preview.redd.it/x2062jsp4wqh1.jpg?width=3064&format=pjpg&auto=webp&s=cba7cf593b30eee3dfaa1caa0fb2546daf89d722 I noticed our house was warm. Ecobee thermostat has a warning cooling wasn't kicking on C myhecked AC unit and the return line (circled in the picture) was covered in frost. I shut off cooling at the thermostat. Check the filter and it was dirty enough that it could have been the issue. Changed the filter. Now nothing will start up. Turning on the fan does nothing”

“Since I’m not allowed to post in the HVAC page as a technician, I’ll post it here. Got a call from a friends mother who was having issues. Found an E6 error code on a comfortaire 2headed ductless. Home has 3 condensers for multiple areas, 2/3 have surge protectors. The 1 that doesn’t have the surge protector on it, has a blown board (this is unit with E6 error & attached the photo), this units about 8 years old. We had some crazy thunderstorms here in the northeast when the unit started thro”

“Hey friends, My mother in laws York furnace was rapidly turning on and off every second, and the light for the code was strobing. Google said the board was shot. I had a tech out who recommended full furnace replacement to the tune of 7-8k (I'm in Detroit, and this sounds really high for a small bungalow furnace, but what do I know). Well my mother in law works at a grocery store and doesn't have the cash, and I figured since the furnace is shot, it couldn't hurt to try to fix it mys”

“There shouldn’t be anything wired into the frost stat. You’re grey and black should be from the room stat terminals only. Make sure you’re doing your 26:9 checks when removing that case on and off 😉”

“My thermostat has been intermittently shutting off and going completely blank, then coming back on its own later with no changes on my end. Already replaced the batteries. It didn't work immediately after replacing the batteries but next day the thermostat automatically turned on, then went blank again a few days later, so I know it's a battery issue or a bad thermostat? System info: Rheem air handler, model RXHF-17, sitting on top of a water heater in a closet. Based on some research, I”

“House came with the unit. Previous owners said they newer used it. Wall mounted thermostat is dead. Not used in a decade a least. I thought about having my HVAC contractor troubleshoot it but birds went in during spring and ripped a bunch off yellow insulation material and aluminum foil. Now I'm not sure if it's even safe to operate it again. I taped it shut but a lot came out. What would you guys do? I don't care much about ever using it. Just don't like things sitting not worki”

“Hello, My plumber and I have been trying to figure out this error. Fan runs fine, but we are getting into colder temps and it won't kick the heat on. My plumber has the thing taken apart and has been working on it for a few days. But can't seem to figure it out. He told me i might have to call one of the "lennox" guys lol. Hes a old school plumber but hes our commercial guy and does all the res furnaces too. Any ideas before i call the other guys on monday? submitted by &”

“power went out in my area for a couple hours last night. When it came back on, the outdoor condenser unit wouldn’t kick on. Everything on the thermostat looks fine (it’s in the Honeywell vision series), as in it is going into cooling mode. The blower is running fine, just not getting any cold air from the condenser obviously (it’s a run tru). We have tried turning the breaker off to the AC for a full hour before starting again. T he entire system was installed new in January of this year. There”

“Before I call a professional installer, I thought I’d ask here. Just moved into a brand new manufactured home. The home included a Nortek Furnace but not AC. We had a 3.5 ton American Standard condenser and coil installed right before we moved in. The home came with a Honeywell Thermostat. We’d like better control so we purchased the Ecobee Premium with sensors last weekend. However, when I sent photos of the existing wiring to ChatGPT, she said something about a heat pump as the O wire was curr”

“It's a commercial rooftop unit, heat pump, dual compressors, 2c/2h stages. Worked fine with old thermostat, but it was all busted up so I replaced it with a wifi unit to have app control over it. I done this many times before, but different HVAC units, this one is a particularly old, big unit. Posting photos of wiring on old venstar, and the jumpers on the back, and the new Honeywell wired up, (on the Honeywell, I moved the white wire to o/b after I took this photo). I'm lost, and now my”

“I have a trane system S9V2B080U4VSBBA I lost power and now that the power came back, I no longer get AC. I have power cycled the furnance / AC / ecobee. The control board shows: Zone1 Open (green) Y1 Compressor (orange) Fan (green) And yet neither the indoor or outdoor unit are responding. At the bottom window of the indoor unit says "IdL" Is there anything else I can try? submitted by /u/Aslimedr_wsnear [link] [comments]”

“I’ve just installed a hive thermostat after watching a few YouTube videos. When turning everything back on the heating works and the thermostat connects to the app but there’s no hot water. Nothing even registers from the boiler . I’ve double checked connections but can’t see anything obviously wrong. Hoping someone will prove me wrong! Thanks in advance for any pointers. submitted by /u/Moist-Instance-2052 [link] [comments]”

“This morning my Honeywell thermostat was flashing an error 53 code. Google said to check the outdoor wiring and this is what I found. I’m assuming an animal chewed on the white cord. Is this something I can fix myself? If so, how? There is no way I can afford to have a company come out right now 😩 submitted by /u/reader-rae [link] [comments]”

“Hi all, just looking for some answers before I call my landlord. I have been trying to figure out why this thing doesnt want to turn on the heat. The AC/cooling is working but not heating. Everytime I try to turn on the heating, I just hear a buzz sound. Trying to get ahead of it before the winter comes and dont want to get stuck without heating Thanks for all who will answer! PS. Cooling was running hence the 77°F temp and the 90°F temp is just me testing the heating submitted by /u”

“I have an old Trane system that works well. Recently the air blower runs almost constantly. The Ecobee smart thermostat shows no equipment running and the fan continues on. I disconnected the thermostat and the fan continues so I think I have it narrowed down to something in the main unit. Perhaps a bad switch. Any experience with this would be greatly appreciated. submitted by /u/Chemical-Ad-3461 [link] [comments]”

“My thermostat says no red wire connected (it is) and is showing Voc O.O2 V and Vin 0.02 v. i was told my fuse may have blown but I don’t see a fuse anywhere. It’s an old unit. What else could be causing the lack of power? submitted by /u/Low_Bluejay510 [link] [comments]”

“Here's another reported issue from Martin, via our emsesp.org email (unfortunately he has no GitHub account). The hc1 set summer mode entity doesn’t work on his IVT Geo 612C. Same with "winter". Only "auto" works. To test, select either “summer” on “winter” in the choice for the writable entity “hc1 set summer mode”, like call thermostat hc1.summersetmode summer which returns: Bad syntax. Check arguments. [command] Command summersetmode: summer failed (Error) He tested and confirmed the correct”

“A few months back I replaced my old iHeat AHS27-D with a Rheem RTEX-27kw. My old water heater I could have three hot showers at the same time. My new one, one shower will be scolding hot but if I turn on a tub spout or open several faucets, it gets an E5 error. The three 240V/40A circuits next to it all show 240V. But when I measure the incoming voltage on the water heater, only Bay 1 (the far right set of red and black) show 240 V. The other 2 sets show ZERO. So why is it going to an E5 error b”

“Our thermostat (Emerson Series 80 non-programmable) was working just earlier this morning, and after I turned the cooling off to clean the unit, I came back to find that the display was weird, half of the display segments were off and the rest of the display was fading. We tried replacing the batteries to no effect. I took the back panel off to look at the circuit board, saw nothing off about it from a glance, and when I placed the batteries back into it, the display started flashing like in the”

“in April, our thermostat failed. I called a company we used before and they installed a Honeywell 8000. everything seemed fine for the first few months. in July, our condo notified us the roof was getting done and all A/c units would be inspected and a group rate would be offered to have units replaced. we agreed to this as our unit was quite old. a different company replaced the indoor and exterior unit. ever since, then I’ve been receiving high humidity alerts. I away for the season from this”

“I have a honeywell pro series. I reset it trying to change some settings back to default. And now only hot air is blowing any quick fix. Orobably some setting I have to do submitted by /u/Dire_Wolfff1 [link] [comments]”

“I work in a lab and it is ALWAYS he wrong temperature. When it's hot outside, it's muggy and hot inside. Cold outside? Even colder indoors. Our maintenance contractor says our HVAC unit is just bad and can't keep up with the air turnover of the space, but I suspect it's more than that. Can someone take a look at this thermostat and let me know if it's wired correctly or if there is some way to test that it is? It's a bit more involved than my home thermostat otherwise I&#”

“Like the title says my thermostat quit working. I can manually turn on my blower motor and a/c unit but I can’t get the thermostat to control those things. It has new batteries in it. Any help would be appreciated. Thanks in advance. submitted by /u/spiraledout80 [link] [comments]”

“I’m wanting to switch back to the Honeywell thermostat from the Google Nest Thermostat E and I can’t find the picture of the wiring I took of it before installing it (my phone took a dump). Anyone offer some guidance? submitted by /u/Kongap [link] [comments]”

“Hi all, I recently just closed on a condo with this roof Magic Chef AC unit from the 80s that's still chugging along with no issue. I wanted to replace the honeywell thermostat with an Ecobee smart thermostat, but it looks like the B wire in the picture below is not providing any power. Does anyone know if the air handler should be located somewhere on the roof unit, so I can check if there is a common wire connection? The pictures were taken during the inspection, and I just wanted to make”

“HVAC was working fine, suddenly there was a power outage and the power was back on within 10 seconds. From then no AC is blowing and no power on Ecobee Thermostat. Any help? I checked 3 Amp fuse on the panel board and looks like it is all good. The purple one. submitted by /u/sstamara [link] [comments]”

“So my thermostat is connected to this smart hub called SmartRent for the apartment and whenever it detects moisture it just turns off the thermostat, there’s no power or anything connected to it. ChatGBT said I need to find the drain and take the moisture out of it, is it anywhere in this picture? It’s currently Labor Day weekend and it’s insanely hot inside submitted by /u/TheCatsButtholee [link] [comments]”

“Old thermostat starting spazing out and turning on and off whenever it wanted because the thermostat died..or something anyway i bought a new one, i have a heat pump w/emergency heat/cool im a low voltage tech by trade but electrical/hvac isnt my thing? can anyone dumb this down for me to the tune of put x-wire on y-post or did i buy the wrong one? submitted by /u/Tony2Wheel [link] [comments]”

“I replaced my own thermostat around 2022 via long-distance help from a friend via text. I remember replacing it in the summer, but I remember waking up feeling like I was in a sauna with the heat stuck on. It was like 97° or something inside. But, I feel like it wasn't unusual for the heat to be on, like it was already winter. I don't know. I do know I tried a few different models and finally got it fixed. I've been paranoid ever since and just randomly keep an eye on it when I walk”

“Hooked up new thermostat as shown and only things that work are the fan and heat but no ac. What did I do wrong here? There's a sixth wire seen at the bottom in the new picture that was not hooked up to anything. It was buried in the wall when I removed the old one. And I know there's a lot of copper showing but I promise you those wires are seated all the way in there. submitted by /u/LazyBrokerAz [link] [comments]”

“Current unit Planning on replacing a thermostat that has been misbehaving (adjusting the set temperature lower without touching it) and I just wanted to make sure my assumptions were correct. The label on the far right wire is illegible but would it be safe to assume that would be the 'C' terminal? Also the wiring diagram of the new unit doesn't have an 'RH' terminal, but I'm assuming that's just the 'R' terminal on the new unit. The old unit is a SimpleComfor”

“Thermostat says error 53. Online says the thermostat to show temp outside isnt working. Why do I care, I never use it to tell the temp outside. Does this error affect more than that? submitted by /u/First_Detective6234 [link] [comments]”

“Yesterday I had a 2 stage carrier installed with the included Ecobee. It went smoothly, the only issue I know of afterwards was with the thermostat wiring, they appeared to have set it so the Ecobee only uses Y1 and W1, and Im assuming the board would've timed the stage switch automatically. I went ahead and redid the wiring so the Ecobee now controls the staging. Don't need help there everything is functioning properly. The only question that came to mind afterwards is did I potentially”

“My Ecobee suddenly went completely black. I found the 3A fuse on the HVAC control board was blown. I replaced it and the Ecobee powered back up and went through calibration, but the fuse blew again shortly afterward. I replaced it again and the same thing happened. Breakers are not tripping. I visually checked the thermostat wiring and the low-voltage wires going to the outdoor condenser and don’t see anything obviously damaged or exposed. It seems like the fuse may be blowing when the system at”

“I am having issue with my home heater/ac unit. I bought my house a few years ago, and I replaced my Thermostat from a Honeywell to a Google Nest 2 (No issue, just wanted to upgrade my thermostat). The AC and heater works fine MOST of the time. During the winter my heater has intermittent issues. Issue 1 - I would set the thermostat to Heater Mode and set it to 78 degrees. On very rare occasions the heater will remain on well after the 78 degrees. Sometimes I noticed the house getting really hot”

“I had my thermostat set at 66° pretty much all summer, forgot to shut the furnace off. We use window air conditioning, don't have central air. Furnace wasn't on this morning, and it didn't need to turn on being 70° in the house. When I walked by the furnace, I heard buzzing. Almost like what it sounds like when it's about to turn on. Still buzzing after a couple hours so I shut it off and hit the breaker off. It's not buzzing anymore. I noticed this part was warm to the touch”

“It's starting to get cold in my area so I used the auto/heating option, and then put it back to cool after an hour or so. I went back home from work and the temp is now 96F. I turned the system off and after 20 minutes it is still blowing room temp/hot air. Any recommendations on how to fix this? Will call the HVAC too in a couple hours because it is way too hot. It is set to heat pump too. submitted by /u/kotsepio [link] [comments]”

“Who knows what the COM ports are for? I’m trying to figure out how to stop this ERV from dumping human air into my house all day without turning it all the way off and for some reason the intermittent mode only lets you use the high fan level as far as I can tell. When it’s 95° at 100% humidity outside, I would rather sacrifice some ventilation and dump the moisture into my house. Honeywell truefresh VNT5150H1000 submitted by /u/Chronofier [link] [comments]”

“We have a space that we're not currently using in our business. Recently I found out that over 100° weekend this space with very drafty windows had its thermostat set at 66° for all day Thursday, Friday, Saturday and Sunday while it was probably an average temperature of 92° outside. So I decided to replace the thermostat with one that I could monitor from home. I got a Nest thermostat and hooked it up. The space is heated/ cooled by a rooftop heat pump and a ceiling mounted air handlerin a”

“Hi, i was hoping someone could help me understand what’s wrong with my HVAC system (Direct Air, manufacturer is Midea). I tried a hard reset and it will start going again but then stops after 10 minutes and displays this error message… I think my thermostat is a Carrier and appears to be discontinued. Can i fix this myself? submitted by /u/sushi_roll3 [link] [comments]”

submitted by /u/useryourname [link] [comments]

“I’m a renter I don’t know much about ac systems. I bought a separate thermometer clearly there is something wrong I’m in Fl I have the thermostat set to 80 and it’s 73-74 in my house and now started making this weird noise and the property maintenance man goes” it’s fine” no sir it’s not fine my ac doesn’t turn off and I have it set to 80 and it’s getting down to 71! At night but “it’s fine” lol Sound it’s making https://www.tiktok.com/t/ZP8cJJj3k/ submitted by /u/Humble-Owl-2972 [li”

“Hey all appreciate any advice. I am a renter, but I try and fix anything I can myself. Last night my thermostat (emerson 1f78-144) was acting strangely again and this time finally showed the low battery message. The toggle switch (off cool heat) also got stuck in the off position. I replaced the batteries today, assuming that would fix both issues. It has not. The toggle switch is still stuck in the off position. I have tried the reset, but i can't move the switch to 'heat' either. I”

“I was checking the internal unit and saw some red numbers flashing in the little window. The thermostat is not showing any errors and the unit is running fine. I’m just curious as to what it means. Has anyone seen these before? Codes: A, 02,, 97 and F0 submitted by /u/freakingout010101 [link] [comments]”

“Has anyone had a problem with a nest thermostat not reading the temperature accurately and having a huge delay with trying to wake the screen ? I noticed yesterday my screen wasn’t turning on when I walked by so upon further investigation when it did “wake up” it was reading 79 although it felt like the normal 73-74 I keep it at plus the air was running. I have another thermometer to test the temp inside my house which confirmed it’s 73 degrees inside. Within 3-5 minutes the thermostat corrected”

“5TTX7048A1000 ac 5PXCC009AS3HA coil S9V2C100U4VSB furnace Honeywell HZ432 zone control (3 zones) Trane XL824's in each zone Home details: 2800sf long ranch style zone1 35%, zone 2 , zone 3 20% unit in encapsulated crawl (straddles zone 2&3 boundary rather than being centered in the crawl) interior walls are 2x6 stud cavities on 16" spacing 3 double and 4 single wall returns in zone 1 2 double and 2 single returns in zone 2 & 3 supply registers at all windows and exterior doors (”

“Having an issue with the thermostat in my new apartment maxing itself out randomly. Maintenance seems to think it's an issue with the increase temperature button caused by paint overspray. They don't really seem to have a solution for that other than to spray it with WD40 until it stops, which I don't want to have to do every other week for the next year. Has anybody dealt with the issue and come up with a real solution? Should I just buy a new cheap thermostat from home depot and ca”

“Came home from work to a hot house (same temp as outside). Cant figure out what’s wrong. The thermostat isn’t dead, only oddity was the set temp number was blinking for a few minutes but then stopped. The fan inside the house is still blowing (not cooled air), but the outside unit isn’t running at all. After being home for an hour, I started to hear the unit make a noise (see video). Any thoughts / advice? I’m a first time home owner, still learning everything. And yes, I have changed the air fi”