[mahidable]

30 year old Bryant unit heater was working yesterday not today. I have 120 volts to the control box, the 732 pilot is still lit. so I bench tested when cold there is no continuity, after heating I have continuity. I do not know what to check next I do not have a wiring schematic. Any sdvise would be a help.
Thanks Mike

[hvac1000]

Look for the high limit control and check

[T-Top]

You should only have two limits a high limit and a roll out limit just above the burners. It sounds like one is open.

[acetc]

In addition to what T-Top said, you could check with a volt meter at the gas valve for 24 volts if you do not have 24 volts see if you are getting voltage (24) to the pilot , these pilots do fail and they have a warp switch in them that makes a set of contacts built in to the pilot and completes the circuit when the pilot gets hot.Good luck, Mike

[mahidable]

Thanks to hvac1000, T-Top, and acetc for your help. I have purchased a new pilot and installed it but the unit still will not fire off. There is only one limit switch that I can find it has two spade terminals and one screw terminal. How do I test this? If I need to replace the limit switch what do I ask for? I have been to the supply house and all I have found are limit switches that have two terminals and dial type temp setting arrows in various temp ranges. There are also high limits that are nomally open and normally closed how do I tell which I need? There are no numbers or anything on the old one to tell me what I have. The transformer tests as good. It sounds like the limit switch is the likely culprit from your replies. I have not tested for 24 volts at the gas valve I will do that tomorrow.