I can't get the thermostat to switch to heat - Heating & Cooling

Principles of Operation - Heated Seats, Vehicles Built 12/2002 Onward
The driver and passenger heated seats share a common ignition feed to the heated seat control switches and share a common ground to the seat backrest elements. The heated seat control switches are a latching type switch; continuity through the switch will remain regardless if voltage is supplied to the switch or not until the switch is pressed to place in the OFF setting. When the heated seat control switch is pressed with the ignition switch in RUN or START, voltage is supplied to the bi-metallic thermostat that is part of the seat cushion element. The seat cushion element and seat backrest element are wired in series and powered by the same output of the bi-metallic thermostat that is part of the seat cushion element. The heated seat control switch also will supply voltage to the separate indicator circuits at the dual automatic temperature control (DATC) module display panel to indicate an ON state. The heated seat will remain on until the heated seat control switch is pressed and voltage is no longer supplied to the bi-metallic thermostat. If the ignition source is removed from the heated seat, the heated seat system will return to the ON with the ignition switch in RUN state until the switch is pressed. The heated seat system is designed to heat the seat to 40?C (104?F) and maintain the temperature by the opening (no voltage to the heated seat elements) and closing (voltage supplied to the heated seat elements) of the bi-metallic thermostat.

If your thermostat is being used with an electric heating system and the fan does not start in heating mode on auto; remove the thermostat from the subcase on the wall and check for a switch on the back of the thermostat. A lot of electronic thermostats have a switch on the back that says electric/heat pump and gas/oil. If you have electric heat or heat pump you need to switch it to this side. Usually this is set at the factory for gas/ oil. Gas/oil furnaces have built in means of bringing on the fan and electric/ heat pumps are brought on by the thermostat.

flow switch timer in the unit. its a part on the pcm board. tell the pump to stay on for 10min after heat up. and does other times as well depending on setup... its not really a switch its a chip but it works as a switch.

make sure the one that says "cool, hot, and off" is switched to off.

Depends on what type of heat you have...if it is electric, it could be your thermostat (some electric heaters use contactors & rely on the thermostat to switch the fan on). Heat pumps also use the thermostat to switch the fan on in heat & cool mode. Most electric furnaces use a sequencer to switch the low speed of the fan whenever there is a call for heat. Gas furnaces use either a fan/limit controller (if the unit is older) OR a circuit board based on time (after the thermostat calls for heat). SO depending on the type of system you have, it could be a bad sequencer, controller, relay, thermostat, or control board. Hope that helps.

Depends on what type of heat you have...if it is electric, it could be your thermostat (some electric heaters use contactors & rely on the thermostat to switch the fan on). Heat pumps also use the thermostat to switch the fan on in heat & cool mode. Most electric furnaces use a sequencer to switch the low speed of the fan whenever there is a call for heat. Gas furnaces use either a fan/limit controller (if the unit is older) OR a circuit board based on time (after the thermostat calls for heat). SO depending on the type of system you have, it could be a bad sequencer, controller, relay, thermostat, or control board.

A thermostat only cuts the heating off when the temperature it is set to is reached while the heating is on. If the heating is set to off then the thermostat will do nothing.
Generally you want to think about when you want your heating to come one and off by using the timer and then the thermostat is just used to ensure that you don't waste energy by exceeding the maximum comfortable temperature.

Hope this helps a little.

see this causes and fix it. God bless you

Furnace Produces No Heat Possible Causes

• Circuit breaker tripped or fuse is blown.
• Thermostat components dirty.
• Loose wires or open connection.
• Bad battery on digital electronic thermostats.
• Heat Either Does Not Reach or Exceeds the Set TemperaturePossible Causes
  
• Thermostat mounted crooked.
• Heat anticipator not set correctly.

Possible Repairs

• Remove cover of thermostat and loosen screws holding unit to wall. Level the thermostat. Re-tighten screws and replace cover.
• To adjust the heat anticipator, please see Heat Anticipator Adjustment.
• 
  Furnace Turns On and Off Frequently ("short cycling")Possible Causes
  
• Dirty thermostat components
• Heat anticipator not set correctly.

Possible Repairs

• Remove thermostat cover and gently clean components especially the bimetallic coil and the switch contact surfaces if the thermostat does not have a mercury switch.
• To adjust the heat anticipator, please see Heat Anticipator Adjustment.

Just a quick thought...make sure that your gas shut off valve is ALL the way open.
In answer to the thermostat question, if the thermostat has completely failed, (open circuit) you're correct, there would be no heat at all. The thermostat contains a tiny heater, controlled by the heat select switch, for instance, if you set the switch to "low heat" the thermostat heater will turn on, applying heat to the thermostat, which means when the main heat turns on, the thermostat will cycle off quicker, because although the air temp may be, say...120F, the thermostat is at 160F. So, that being the case, you could possibly have a problem with the temp switch applying voltage to the thermostat heater constantly, and excessively. Or, the thermostat could just be cycling too quickly. This could be tough to pinpoint exactly without taking some voltage readings with the machine running....one way to check the switch is to remove the two small wires from the thermostat, (leave the larger wires on) and see if it heats properly, that would mean the switch is bad. Please remember to unplug and verify that there is no voltage with a meter before messing with any wires. Hope this helps narrow it down....

If the new thermostat is heat pump compatable.