MEDIUM URGENCY

Rheem Code 59 - Condensate Overflow Switch Open

Code 59

Condensate overflow switch tripped - drain blocked or pan full.

Brand: Rheem (Also covers Ruud) | Equipment: Gas Furnace

What This Code Means

Code 59 on Rheem (Ruud) means the condensate overflow safety switch has opened. The drain pan is full or the secondary safety switch detected an overflow condition.

Likely Causes (Ranked)

Most common

Blocked condensate drain

What: Drain line clogged, water backs up.

How to check: Inspect drain line and pan.

Fix: Clear drain.

Common

Failed condensate pump

What: If you have a pump, it stopped working.

How to check: Listen for pump operation.

Fix: Replace pump.

Less common

Stuck overflow switch

What: Safety switch failed in open position.

How to check: Tech test continuity.

Fix: Replace switch.

Diagnostic Steps

Cut power
Check condensate pan for water
Clear drain line
Verify pump operation
Replace switch if continuity fails

Frequently Asked Questions

Difference between Rheem code 58 and 59?

58 = condensate drainage fault detected by furnace; 59 = secondary overflow switch tripped (worse - more water present).

Same on Ruud?

Yes.

DIY?

Drain clearing yes; pump or switch replacement moderate difficulty.

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Need More Help?

Try our interactive symptom diagnostic tool or browse Rheem parts.

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