Applies to:

Replacing the Air Temperature Probe

To avoid electrical shock or property damage, disconnect power before installing or servicing equipment. A qualified technician must perform the service procedures.

Using a crosshead screwdriver, remove the four screws securing the front panel.
Lower panel, remove connectors from the back, and remove panel from unit.
Unplug the wires to the probe.

Using a multimeter, or ohmmeter, check across the probe terminals for the correct ohms using the RTD Resistance Chart.

RTD Resistance Chart

Temperature (Fahrenheit)	Temperature (Celsius)	Resistance Ohms
50	10,00	1 039,02
60	15,56	1 060,65
70	21,11	1 082,24
80	26,67	1 103,80
90	32,22	1 125,32
100	37,78	1 146,81
110	43,33	1 168,26
120	48,89	1 189,67
130	54,44	1 211,05
140	60,00	1 232,39
150	65,56	1 253,70
160	71,11	1 274,97
170	76,67	1 296,20
180	82,22	1 317,40
185	85,00	1 327,99
190	87,78	1 338,57
200	93,33	1 359,69
210	98,89	1 380,79
212	100,00	1 385,00
220	104,44	1 401,84
230	110,00	1 422,86
240	115,56	1 443,85
250	121,11	1 464,79
260	126,67	1 485,71
270	132,22	1 506,58
280	137,78	1 527,43
290	143,33	1 548,23
300	148,89	1 569,00
310	154,44	1 589,73
320	160,00	1 610,43
325	162,78	1 620,77
330	165,56	1 631,09
340	171,11	1 651,72
350	176,67	1 672,31
360	182,22	1 692,86
365	185,00	1 703,13
370	187,78	1 713,38
380	193,33	1 733,87
390	198,89	1 754,31
400	204,44	1 774,72
410	210,00	1 795,10
420	215,56	1 815,44
430	211,11	1 835,74
440	226,67	1 856,01

If the probe proves faulty, continue onto step 5.

Using a 3/4" wrench, loosen probe strain relief and pull the probe from the unit.
Slide new probe through the strain relief, extending the probe about 1" (25.4 mm) into the cabinet area.
Plug probe wires to the unit, tighten the strain relief, and replace front panel. Unit is now ready for use.