3 ton carrier gas pack

[carman]

i do not have the model number available. this is a 3 toncarrier weathermaker gaspack. i can not get the heat to operate. when the thermostat is calling for heat nothing happens. i checked voltage on the terminal board and it is calling for heat. i can jump out r&w and the draft motor runs and the burners ignite. i can jump r&g and fan runs. but i can remove tstat from unit and wire heat and fan to r terminal and nothing happens, unless i pull the pin from the board that goes to the rollout and limit the fan and draft motor start but no burner. what am i missing here? i have to admit i do not work on much heat. i checked limits and rollout switch they are good. any help is appreciated.

[BMH_SE]

How did you remove the tstat from the unit?

[hvac69]

In one sentence you say I jump R to W inducer starts and burners light, Then you say "you pull the thermostat and wire R to W and R to G but nothing works. Statements make absolutely no sense. Then you pull what I am assuming is the safety circuit is why only the fan runs. My suggestion get good liability insurance before you burn something down.

[socotech]

Let me try. Heat works when jumped out at the unit. Doesn't work when thermostat is "calling" for heat. Unit also doesn't work when jumped out at thermostat. Is this correct? If so, I would suggest looking for a smoke detector or a fire panel.

[timebuilder]

I would encourage you to call a qualified tech. I will not give step by step instructions in an open forum to a regular member.

Sorry.

[Nytefog]

Possibly is their a break in the control wire from the thermostat. If the thermostat is calling what reading do you get between r & w at the furnace. Also, check the reading from R & W at the control wire coming from the themostat at the furnace to see if r&w is closed. If that is close start check the control/limit circuits and hop scotch around using the wiring diagram. This should be a fairly simple diagnosis and repair. Your meter is your best tool for troubleshootin. If you learn how to use your DDM, and its functions, you will be able to diagnos quite quick.

BTW, make sure you have a good DDM and make sure to change your batteries and not use the meter when the battery is low.

Let us know what you find sir.