Dead Thermostat Batteries / Condenser Fan Squeaking – Cooling Call Delay

Quick Summary

System initially appeared to have a no cool issue because the thermostat was not operating correctly.
The thermostat was battery powered with no common wire, and weak or dead batteries were found. After replacing the batteries and allowing the built in delay to clear, the system started.

Once running, the outdoor unit produced a squeaking / scraping sound from the condenser fan section.
Motor amperage was below nameplate FLA, and the noise could still be felt and heard when the blade was turned by hand, pointing more toward a mechanical fan assembly issue than an immediate electrical failure.

System Info

System: Straight Cool Condensing Unit
Location: Outdoor Unit / Indoor Closet Air Handler
Outdoor Temp: Not Recorded
Delta T: Not Recorded
Subcooling: Not Recorded
Superheat: Not Recorded

Customer Complaint

The property was vacant.
Reported issue was that the condensing unit fan motor sounded extremely restrictive, and the A/C was not functioning.

What I Found

Thermostat appeared blank or not operating normally
- A blank thermostat does not always mean the thermostat itself has failed. Low battery power can interrupt the control signal and make the whole system appear dead.
Thermostat was battery powered with no common wire connected
- If there is no common wire, the thermostat depends on battery power for operation. In those cases, weak batteries alone can stop a cooling call.
System control depended on thermostat battery power
Existing batteries appeared weak or dead
Batteries were replaced and thermostat was reinstalled
Indoor unit was located inside a closet with difficult access due to a wall directly in front of the unit door
Indoor section was opened to check the control board
System was found sitting in delay, then began operating once the delay cleared
After startup, the outdoor unit produced a squeaking / scraping sound
Noise appeared to come from the condenser fan section during operation
Condenser fan motor amp draw was checked on the black lead and measured approximately 0.8A. Fan motor nameplate listed 1.3A FLA
Motor was drawing below rated full load amperage at that time
Power was shut off at the disconnect and capacitor wires were removed for testing
Dual capacitor was rated 35/5 µF. Measured values were approximately 31 µF and 4.7 µF.
Fan side was close to rating, while the 35 µF side was reading low
- Study Note: A weak capacitor can contribute to harder starting or weaker performance, especially on an older system, even if it is not the main complaint.
System was restarted and the squeaking / scraping sound returned
Power was shut off again to avoid forcing operation while checking the fan assembly
Condenser fan top was opened and blade was turned by hand
A light dragging / squeaking sound was still present by hand
- Study Note: If noise is present even with power off, the issue is more likely mechanical than electrical.
Shaft / bearing area was cleaned using a wire brush and drill brush
Fan blade removal was attempted with an adjustable wrench, but the blade would not come off easily
This suggested the blade may have been seized to the shaft
- Study Note: When the blade is seized, replacement planning becomes important because removal may damage the blade or motor shaft.
Lubricant was applied into the inner shaft area
After lubrication, the noise decreased or stopped at that time
However, it was not possible to confirm whether that improvement would last
Condensing unit appeared to be an older system, likely around 1998
Visible rust and overall age-related wear were present
A pressure check was considered, but the plan shifted toward confirming operation with temperature split and documenting condition with photos and video
Noise was still lightly present at times, but not severe enough in that moment to justify forcing blade removal and risking a complete failure

Diagnosis

The initial no-cool condition was most likely caused by thermostat battery failure, not by an immediate equipment lockout or major electrical fault.

After replacing the batteries and allowing the normal delay to clear, the system responded and began operating. That supports loss of thermostat power as the main reason the system did not start at first.

The outdoor noise appears to be a mechanical condenser fan issue.

Main reasons:

The noise came from the condenser fan section during operation
A dragging / squeaking sound was still present when the blade was turned by hand
Motor amp draw was below nameplate FLA, which makes an immediate overload condition less likely
The fan blade appeared difficult to remove, suggesting shaft corrosion, seizure, or bearing-related wear
Cleaning and lubrication reduced the noise, but that improvement may only be temporary
The dual capacitor was not completely failed, but the 35 µF side was reading low at about 31 µF.
That may affect performance on an older system, but it did not appear to be the primary cause of the fan noise.

Recommended Action

Replace thermostat batteries and verify stable thermostat operation
Completed
Confirm proper cooling call from thermostat to indoor board after battery replacement and delay completion
Document condenser fan noise with photos and video while the system is still operating
Advise that the condenser fan motor / blade assembly is aged and may fail later even if it is currently running
Do not force fan blade removal unless fan motor and blade replacement are already planned
If the squeaking returns or worsens, recommend condenser fan motor replacement and inspect whether the blade should also be replaced
Recommend replacement of the dual capacitor if approved
The 35 µF side was below rated value, and replacement is reasonable for a system of this age
Verify final cooling operation including thermostat call, condenser fan operation, compressor operation, and temperature split
Advise that this is an older R-22 system, so age-related failure risk remains even if the system is currently operating

Study Note

Battery-Powered Thermostat Can Cause a No-Cool Call

When a thermostat has no common wire, weak batteries can stop the control from sending a stable cooling call.
That can make the system appear dead even when the equipment itself is still capable of running.

Fan Noise by Hand Usually Points to Mechanical Drag

If the condenser fan blade still drags or squeaks when turned by hand, the issue is often mechanical.
That usually points toward shaft corrosion, bearing wear, or a blade hub seized onto the motor shaft rather than a simple control problem.