Is my air pressure switch bad?

[ag62]

My minimax heater doesn't ignite. Air blower fan keeps blowing forever and service light is on. I take off rubber tubing and blow some air directly into air switch, then I put tubing back and it works for day or two. Here is the picture of the switch. What does .65"VF means? I couldn't find exact part number, but found RSS-495-11 model from Grainger.

Anyone knows if this would work? Thank you

 

[Butterfly]

 

[Bama Rambler]

The RSS-495-11 will work. The difference is that the RSS-495-090 is a non-adjustable OEM switch set at .65" WC (water column).

The RSS-495-11 is adjustable and comes from the factory set to .25" WC.
To adjust it to .65" WC you need to turn the adjusting screw 2½ turns clockwise facing the screw. each turn of the screw = ~.16" WC

 

[ag62]

You guys are great.Thank you very much.