Rheem RGPH-07EAMGR Error Code 3 Blinks (2-sec pause): Limit Switch Is Open

What Does Code 3 Blinks (2-sec pause) Mean?

The high-temperature limit switch protects the RGPH-07EAMGR's heat exchanger by opening when supply-air temperature climbs too high. Three blinks then a 2-second pause on the UTEC 1012-925 IFC report that this limit has opened and the board has shut the burners down.

Overheating almost always comes from restricted airflow across the heat exchanger. On this single-stage furnace the blower moves a fixed volume of air, so a clogged filter or closed registers quickly let heat build up past the limit's setpoint. Less often the blower motor itself is not moving enough air, the limit switch has failed, or a wiring connection to it is loose.

This code concerns indoor circulation and is distinct from venting codes such as the pressure switch open code (2 blinks), which is about exhaust draft rather than the heated air leaving the furnace. Repeated limit trips stress the heat exchanger, so the underlying airflow restriction should be corrected rather than ignored.

What You'll Notice

• The status LED repeats three blinks then a 2-second pause.
• The furnace heats briefly, then shuts the burners off while the blower keeps running to cool things down.
• Airflow from the registers feels weak, or some rooms get little air.
• The filter looks gray and clogged when held up to the light.
• The furnace short-cycles — firing and dropping out repeatedly.

Common Causes

How This Is Diagnosed

The cause is isolated from the easiest airflow restriction outward. The air filter is checked first because it is the most common culprit, then supply and return registers are confirmed open and unblocked. If airflow is still poor, a technician checks the blower motor and wheel, verifies the limit switch closes when the furnace is cool, and inspects its wiring for a loose connection.

How to Fix It: Restore Airflow (Filter and Registers)

What You'll Need

• New air filter (correct size) 🛒 Find at FiltersFast · 🛒 Find at Amazon
• Flashlight

Steps

1. Shut off power and gas before you start Turn off the furnace power switch or breaker and shut off the gas supply before opening any panels. If you smell gas, leave immediately and call your gas company from outside. Let the furnace cool down before you start.
2. Check and replace the air filter Locate the filter in the return duct or blower compartment. Hold it up to a light; if you cannot see through it, replace it with a new one of the same size, with the airflow arrow pointing toward the furnace.
3. Open and unblock all registers Walk through the home and make sure supply and return vents are open and not covered by rugs, furniture, or closed dampers. Restricting too many registers starves the blower of airflow.
4. Restore power and let it reset Reopen the gas supply and restore power. The limit switch resets automatically once the furnace cools, so heat should return on the next cycle.

When to Call a Professional

Contact a licensed HVAC technician if:

• The furnace keeps tripping the limit after the filter is replaced and registers are opened
• The blower runs weakly, does not start, or makes grinding or rattling noises
• You notice a hot smell, or the furnace shuts down almost immediately after firing
• The limit code appears with no obvious airflow restriction

✓ Verified against manufacturer service manual — March 2026