3-blink on Mr Heater HELP

[Joah_from_Alberta]

Hiall, our new (2 years old) Mr Heater MHU50 garage heater stopped working. It is blinking 3 times. We tried to remove the white vacuum line going to the blower and use a paper clip (it seems to only go in as far as the ****** then stops against something metallic). Also when I try to put pressure to the valve using my mouth it either only goes in very small then stops or goes out very small then stops (like the valve is not allowing the flow??)

I confess I did not spend much time learning about HVAC but I want to be able to repair this on my own. Any support or help would be appreciated.

 

[D45]

Does the access panel have a fault code guide on what the 3 flashing lights mean, or the owners manual?

 

[Joah_from_Alberta]

Does the access panel have a fault code guide on what the 3 flashing lights mean, or the owners manual?

Yes thank you for your reply, it states: 3 Flashes Pressure switch failed closed before CAB is energized or failed open after CAB is energized.

I'm starting to think should the diaphragm allow for vacuum into the soft rubber line when it is energized? Because when I blew into it, it would only a small movement either way.

 

[Andy670ho]

Hi did you get this fixed? You should be able to run a drill bit or something by hand way past the ****** depth, this will build inside causing the fault, need to clean it every year if possible

 

[fitter30]

Yes thank you for your reply, it states: 3 Flashes Pressure switch failed closed before CAB is energized or failed open after CAB is energized.

I'm starting to think should the diaphragm allow for vacuum into the soft rubber line when it is energized? Because when I blew into it, it would only a small movement either way.

They move very little. Switch only moves 1/8". Might be able to see the swich move with a long enough hose or with a ohm/ continuity meter.