20 Most Recent Honeywell ER150B Air Conditioner - Page 8 Questions & Answers

Did you set the minimum and maximum settings on the thermostat? When they come new the settings are set to about the same temperature. One must set the upper and lower temperatures manually.... Regards Geoff

https://www.manualslib.com/manual/576182/Honeywell-Th2110dv.html?page=5#manual

Pop the front cover off.

Is there power to the unit?

https://www.askmehelpdesk.com/advice/t-52979.html

Check the voltage coming off the thermopile it should be 600mille volts .

On a Honeywell thermostat the flashing means that the system is in a delay to turn on the compressor. This is used to protect the compressor from coming on and off too often. The normal delay is about 5 minutes. After that the system should come on. If not there is s problem.In order to help us help you we will need a little more information. What happens either at the inside unit or at the outside unit after the thermostat stops flashing "Cool"? Any fans come on? Do you hear a "KLUNK"? Any sparks? Please let us know so we can help.

Thermostats have multiple issues when you start checking them against thermometers. 1) the built-in thermometer may not match the set temperature because one or both need calibration. Compare the built-in to an external thermometer and see if there is any adjustment to make them match. Record the setting on the thermostat and the temperature when it starts and stops -- there should be a 1-3 degree range which may be adjustable. The set point should be in the middle of the on-off temperature spread. 2) the thermostat has a heat anticipator setting which may be set poorly -- turning off the heat before it reaches the set point - the fan normally runs for 1-2 minutes after the heat source is off. The anticipator is used to stop heating before reaching the set point as there are still a lot of BTUs coming out during the fan run-down -- usually 1-2 minutes.

https://customer.honeywell.com/resources/techlit/TechLitDocuments/69-0000s/69-2229ES.pdf

https://www.google.com/search?q=Honeywell+thermostat+RTH2310+back+to+factory+settings&oq=Honeywell+thermostat+RTH2310+back+to+factory+settings&aqs=chrome..69i57.1324j0j4&sourceid=chrome&ie=UTF-8#kpvalbx=_05ChXc6kBa-b_Qb8u6GADw22

Actually the 24 hour time makes it easier to correctly set the thermostat for when you want it to change setting.

No battery backup in this thermostat.

You need to remove the thermostat from the wall plate to change the battery. Look on the bottom of the thermostat for a locking screw. Loosen this screw with an appropriate screw driver. Then pull the bottom of the thermostat away from the wall plate and then lift up from the bottom. When you put the thermostat back on, line up the brackets at the top of the thermostat with the slots on the wall plate. Then push the thermostat against the wall plate and tighten the locking screw. The documentation for the Honeywell RTH2300B1012/U is available on the product page: https://www.honeywellstore.com/store/products/5-2-day-programmable-thermostat-honeywell-rth2300b.htm . Click on the Manuals tab. See page 4 (page 6 of the PDF) for removing the thermostat from the wall plate. See page 9 (11 of the PDF) for replacing the batteries and putting the thermostat back on the wall plate. The current link to the manual is https://www.honeywellstore.com/store/images/pdf/rth2300b1012-u-5-2-day-programmable-thermostat.pdf . I hope this helps. Cindy Wells

A manual is what you need to unlock and reprogram the schedule. Keep off the set up steps for the thermostat, only the scheduling and security steps. https://www.manualslib.com/manual/1189747/Honeywell-T6-Pro.html?page=8#manual

Terminal X is also common.

Remove the faceplate of the tstat. If fan still continues to run you likely have a stuck fan relay in the unit.

Expose the wires and carefully put the yellow wire in with the red. See if outdoor unit kicks on.

try this web site for your manual. I think this is what you are looking for. https://customer.honeywell.com/resources/Techlit/TechLitDocuments/68-0000s/68-0280.pdf

Without seeing the wiring diagram, I can only say that the MV/PV terminal in many cases is used as the common from the thermostat/transformer. Usually, the 24 volts is supplied to the thermostat from a step down transformer and the thermostat sends voltage to the controller. I would hesitate to "guess" at this without a complete understanding of the wiring requirements. Any HVAC tech should be able to help you.