I have a Rheem RGPN 12EARJR that tripped the high limit safety switch. There was an air restriction that was the source of the problem. Where is the reset?

SOURCE: furnace

It's always possible that the limit "dial" switch is sticking leading you to believe that it's only at 150º.

How old is the furnace and when was it last cleaned.

SOURCE: High limit switch open on armstrong furnace

If you know where the high limit switch is you can always cut the two wires and wire them together causing the limit to close. But what you have to watch out for is why the high limit is not closing. That means in your return air either you have a dirty return air duct, dirty filter, or you don't have all your registors open to allow the heat to escape the heat exchanger. Just watch over riding the system. The high limit switch should either be on or behind the blower, in the middle of the system right under the heat exchanger. any other questions about hvac just ask.

David

SOURCE: high pressure switch keeps popping out

generally this means that the condenser coil need to be cleaned.

SOURCE: i have a tempstar combine air conditioner and

If the unit is around 6 years old then it could be the combustion air motor. If the unit is older then you need to inspect the heat exchanger for signs of cracks. Take the top off the unit to inspect. Check to see if the metal around the reset is hot and if it is then the switch is doing it's job. If the heat chamber is cracked then turn the gas off, because your home will have CO. This can kill you.

SOURCE: I have a rheem gas

Depending on the age of your furnace the limit swithes are part of the control board and are not individually serviced. You will need to replace control board. On the older units that used a seperate fan and limit the only thing you could do was change temperature settings. Hope this helps. Thanks