Classic TXV or metering-device symptom – the system keeps up in mild weather and falls behind above about 95 degrees. Oklahoma runs long stretches past 100, so this shows up as a July problem and disappears in September.

This is most common in homes built roughly 1980 to 2000. The polybutylene and aluminum-wiring window, 150 amp panels, R-22 systems and first-cycle architectural shingle.

Related

• Ductwork threaded through a house built for floor grates
• One central return for the whole house
• Water heater vents into the chimney and the furnace no longer does
• Silver-wrapped tape on old duct joints
• Additions still on window units
• Uninsulated walls and an oversized condenser
• Furnace runs but the house never warms evenly
• Electrical panel cannot support a modern condenser

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Written by Jaylan Jones. I Like To Fix earns a referral fee when a call connects to a contractor. See our business-model disclosure.