Bradford-White Corp C)*(N, PDX75S70F(B, CX), PDX65S65F(B Blower Temperature Switch Testing

PDX Series

PDX SERVICE PROCEDURE V

Blower Temperature Switch Testing

and Replacement

Blower Temperature Switch		WARNING
Testing.		120 volt potential exposure. Use caution
Step 1.	Position power switch on gas control	to avoid personal injury.
	to the “OFF” position.
Step 2.	Remove tubing from inlet pressure tap.	19
Step 3.	Remove the three screws (Phillips screw driver) from
	control access cover on blower and remove cover (see
	photo 19).
Step 4.	Locate blower temperature switch (see photo 19)

Switch Setting

Opens on rise @ approximately 165°F Auto resets on fall @ approximately 130°F

20

Blower temperature

switch location

Cool switch to	Air mixing inlet
below 130°F

Disconnect wire leads to

N

switch. Using a multi-meter

Replace switch

set to the ohms setting, is

(see page 24)

there continuity between

the switch terminals?

Y

N

Common causes for

Reconnect wire leads and

Exhaust

high exhaust temperature

observe heater operation.

1.

Y

Do switch

Y

Vent length is below minimum allowable.

Do exhaust gas

temperature is

2.

Vent diameter not to specification.

contacts open?

temperatures rise to or

too hot.

3.

Restricted dilution air inlet.

above 165°F?

4.

Missing or deteriorated flue baffle.

N

5.

Gas pressure is out of specification.

Do switch

Y

Replace switch

contacts open?

(see page 23)

N

Switch OK

Page 23

23