HVAC component needs ID

[Bob Elliott]

This is a standard gas operated HVAC unit mid efficiency about 5 years old.

Trying to identify what this thermocouple looking component is.

It is just below the A/C lines

[Chad Norlen, CPI]

It's the remote temperature sensor for the thermostatic expansion valve (TXV), but it needs to be in intimate contact with the suction line to work properly.

In this position it would incorrectly determine that the superheat is way too high, and constantly flood the evaporator with too much refrigerant.

[Bob Elliott]

I see one end of the sensor going into the casing so could it be directly attached there inside?

I noticed so telltale green on the burners plate and suspected this sensor.

Where would this normally be seen as I have never Observed one in this location before ?

[Chad Norlen, CPI]

Originally Posted by belliott

I see one end of the sensor going into the casing so could it be directly attached there inside?

Yes, it's attached to the TXV, which is what the discharge (high side, small tube) is attached to inside the casing. It's part of the cooling and has nothing to do with heat.

I noticed so telltale green on the burners plate and suspected this sensor.

Because it is not mounted correctly and the evaporator is being flooded, I'm sure this area would get very icy when operating. The water dripping off the copper would account for the green.

Where would this normally be seen as I have never Observed one in this location before ?

Optimal location is as close as possible to end of evaporator, which is usually inside the casing, or is outside sometimes. If it is outside like this one, it should be insulated. You normally wouldn't see it unless you inspect the evaporator coil as part of your inspection.

[Bob Elliott]

Thanks Chad.
That helped me a lot to complete the report.