• Please note, some of the links on our site are affiliate links (Learn More)

Need to replace Probe/Feeler on A/C .... have question


Premium Member
Aug 19, 2019
Model Number
Sears Kenmore
More than 10 years
Guys Im getting PF error on my old Portable A/C unit. From what I read on internet its the bad probe/feeler sensor thats attaches to the brass tubes. There is no way to get this part anymore 129- for my unit so I was thinking of bypassing the sensors some how or maybe buying similar probe from parts store and just splice it in place of the bad one. Would that work? Are all probes/feelers the same? Also there is a another wire coming off the probe wire that ends with like a black rubber bulb what kind of sensor is that? How about disabling the probe/feeler all together? Any ideas to get the A/C working?

Hi Erikmarko,

Normally the thermal sensor is a thermistor snapped on the copper directly. The thermistor is a resistor modifying the value of 5VDC to a specific voltage. This voltage is converted by DAC (Digital Analog Converter) and with a formula, the value read by the microcontroller is the ambient temp. Without having access to the appliance BOM, hard to find an equivalent because the Thermistor is in two kinds of types: NTC and PTC. N and P stand for Negative and Positive, TC is for Temperature Coefficient. Because it's a resistor, you have to find the MAX value of this resistor which is normally 10K Ohm. Negative and Positive mean if the resistive element will increase or decrease the resistance.

You can try to buy some components on eBay, it's really cheap, or you try to look on the resistor to see if you can't find a part number.

Good luck
Thank you for the info. Looks like this will be well over my head.... It might be a time for a new ac unit.
If you feel that you have benefited from this site, and would like to show your appreciation.