Rheem and Ruud furnace code 22: main limit open

Furnace control display or LED

22

“Main Limit Open”

Printed on 14 model series · 14 documents

(-)92P & (-)(-)92MSP, (-)92T & (-)(-)92MSX, (-)95P & (-)(-)95MSP, (-)95T & (-)(-)95MSX, (-)96P & (-)(-)96MDP, (-)96T & (-)(-)96MDT, (-)96V & (-)(-)96MDV, (-)97V, (-)98V, (-)802P UPFLOW/HORIZONTAL & (-)(-)80MDP, (-)802P DOWNFLOW & (-)(-)80DDP, (-)802V UPFLOW/HORIZONTAL & (-)(-)80MDV, (-)802V DOWNFLOW & (-)(-)80DDV, Fault code label 92-103343-01-00 · 92-24161-118-16 p. 87; 92-24161-154-03 p. 87; 92-24161-111-17 p. 87; 92-24161-120-16 p. 87; 92-24161-122-12 p. 88; 92-24161-157-04 p. 88; 92-24161-124-12 p. 115; 92-24161-126-04 p. 98; 92-24161-159-03 p. 95; 92-24161-146-05 p. 40; 92-24161-147-04 p. 35; 92-24161-148-07 p. 68; 92-24161-149-06 p. 63; 92-103343-01-00 p. 1

Technician

What it means

22 says the furnace control found the main limit open. Rheem’s fault cards explain that this normally means the temperature inside the heat exchanger area has gone above a set critical value, and gas heat is not allowed until the limit cools back to within normal parameters. Other modes such as cooling should still work 95P: 92-24161-111-17, p. 91; 96P: 92-24161-122-12, p. 92; 96V: 92-24161-124-12, p. 115.

On the 95P and 96P cards the control answers an open limit by running the blower at maximum heat speed and the inducer at high speed, with the gas valve off, until the limit closes again; cooling and fan calls are answered as normal. Once the limit closes, the blower runs through a 90-second off-delay. If the limit was open less than 150 seconds (2 min 30 s), operation then goes on as normal. If it was open longer, the control declares a dead (non-functional) blower, enters a one-hour lockout and shows 10 and 61 in turn 92-24161-111-17, p. 91; 92-24161-122-12, p. 92. While the limit is still open after 150 seconds in a call for heat, the display alternates 61 and 22 until it closes 801T: 92-24161-144-09, p. 39. After four dead-blower declarations in one call for heat, the control enters a hard lockout with 61 92-24161-144-09, p. 40.

The card lists six causes: no airflow, insufficient airflow, a faulty limit control, loose or faulty wiring, a dead blower, and input too high 92-24161-111-17, p. 91.

The cards describe the main limit closing again once it cools. The limit that has to be reset by hand is a different one, the manually reset limit control, also called the rollout limit, and its code is 33. When it opens it must be pushed back to the closed position manually, and the 33 card says this fault “indicates a very serious problem that must be repaired before furnace operation can continue” 92-24161-111-17, pp. 91–92. The owner’s manuals give no step for either limit.

Check these first

Rheem’s owner’s manuals have no code list and no reset (92-20802-128-03; 92-20802-130-02). For a furnace that will not operate, the last of their operating instructions gives two steps 92-20802-128-03, p. 4; 92-20802-130-02, p. 4:

1. Turn off the gas to the furnace by “To Turn Off Gas To The Appliance”: shut off the manual gas valve in the gas supply piping outside the furnace casing, set the thermostat to its lowest setting, turn off all electric power to the appliance if service is to be performed, remove the burner access door, turn the gas control knob or switch to OFF and replace the door 92-20802-128-03, p. 4. In that list the power step is conditional, but the manual’s warning is to turn off electrical power to the furnace before removing the front access door 92-20802-128-03, p. 7, and its operating instructions turn off all electric power before the burner access door is removed 92-20802-128-03, p. 4. Full steps: shutting the furnace down.
2. Call your service technician or gas supplier 92-20802-128-03, p. 4.

If the furnace overheats, the owner’s manual says to turn off the manual gas valve to the furnace before turning off the electrical supply 92-20802-128-03, p. 1.

Insufficient airflow is one of the causes, and the card’s answer to it starts with “Check ductwork and filters” 92-24161-111-17, p. 91. Filters are the maintenance item the owner’s manuals leave to you: keep the air filters clean, inspect them monthly and replace them if necessary, and have your installer, service agency or gas supplier show you how to reach them 92-20802-128-03, p. 7; 92-20802-130-02, p. 7. The same page says dirty filters can restrict airflow, and its warnings say to disconnect main electrical power to the unit before any maintenance and to turn off electrical power before removing the front access door. The manuals also ask you to arrange furniture and drapes so the supply registers and return grilles are unobstructed 92-20802-128-03, p. 4. That is the manual’s general upkeep, not a fix for 22: the rest of the card’s checks are service work.

When to call a licensed technician

The card’s solutions 92-24161-111-17, p. 91:

• The blower: whether it turns during heat or any other mode. If it does not, a blower motor fault should also be present; then the wiring to the motor and the motor itself.
• Ductwork and filters, the static pressure against the furnace’s published values, and the firing rate and outlet air temperature against the nameplate maximum values.
• Replacing the limit control.
• Checking and repairing wiring and connections.
• Input too high: the burner orifice size, and the manifold pressure at high fire against the nameplate values.

If 22 alternated with 61, or the control locked out with 10 and 61, the 61 page has the blower causes. The owner’s manuals leave routine maintenance to a qualified installer, service agency or the gas supplier 92-20802-128-03, p. 7.

Notes for different models

Series	Where	Wording	Source
92P, 92T, 95P, 95T, 96P, 96T, 802P	code list	“MAIN LIMIT OPEN”	92-24161-111-17, p. 87; 92-24161-122-12, p. 88; 92-24161-146-05, p. 40
801S, 801P, 801T	code list	“MAIN LIMIT OR HALC OPEN”	92-24161-142-15, p. 39; 92-24161-144-09, p. 39
801S, 801P, 801T	troubleshooting legend	“Main limit open / HALC limit open”	92-24161-144-09, p. 50
96V, 97V, 98V, 802V	fault card	“MAIN LIMIT OPEN”; HALC has its own code, 23 “HALC OPEN”	92-24161-124-12, p. 115; 92-24161-126-04, p. 98; 92-24161-159-03, p. 95; 92-24161-148-07, p. 68; 92-24161-149-06, p. 63
801T Ultra Low NOx	fault card title, read from the page image	“MAIN LIMIT OPEN/AUXILIARY LIMIT OPEN”	92-24161-164-01, p. 35
96V, 97V, 98V	diagnostics charts	“Main Limit Switch Open”, fault level 1,2	96V-chart; 97V-chart
Fault code label 92-103343-01-00 (listed on the RGGE and RGJF support pages)	label, no models printed	“Main Limit Open”	92-103343-01-00, p. 1
RGPN, RGPS, RGLN, RGLS	blink legend (green LED), 3 blinks	“Limit circuit open”	92-24161-38-12, p. 39

The blink legend is a different board, and no document matches its counts to the two-digit codes. The 96V card describes the control’s response differently from the 95P card. If 22 occurs during heating, the blower stops at once and the furnace shuts down with a post-purge, and nothing else runs until the fault clears. It adds a hard lockout, requiring repair and a manual reset of power, after the main limit has opened four times in a row for more than 150 seconds each, or after it opened at “40 heat rate” and did not close within 150 seconds 92-24161-124-12, p. 115. On the 96V the 23 card says the furnace as configured does not include an HALC control 92-24161-124-12, p. 115.

The 22 cards in the 97V, 98V and 802V manuals carry the same title, but their text could not be extracted, so this page does not paraphrase them 92-24161-126-04, p. 98; 92-24161-159-03, p. 95; 92-24161-148-07, p. 68. The 801 series manuals have no fault cards.

For Ruud, the documents show only the replacement-parts line “www.myrheem.com/myruud.com” in the 802P manuals 92-24161-146-05, p. 50; 92-24161-147-04, p. 46 and the model name R801T on both a Ruud and a Rheem specification sheet (G22-556 Rev 8; G11-662 Rev 7); none ties a Ruud furnace to a series on this page.

Related Rheem and Ruud codes

• 61 “BLOWER FAULT – BLOWER UNABLE TO RUN”
• 33 “MRLC (MANUAL RESET LIMIT CONTROL) (AKA ROLL-OUT) OPEN”
• 23 “HALC OPEN”

See also

• Heat pump vs gas calculator
• HVAC and furnace tax credits in 2025 and 2026: 25C, 25D, 30C

Other gas furnaces: Carrier, Goodman, Lennox

All Rheem and Ruud codes

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