Carrier Weathermaker (58MXA) code 31

[sjr]

Hi! I have a problem w/my Carrier Weathermaker 9000? (it's a 58MXA) not heating.

Though the "component test" checks out OK, this is the ONLY time that I see that I see the HSI energized (the ignitor). Also, the test of the pressure switch in the op's manual (i.e., disconnect the inducer motor, call for heat, and make sure that the HSI is NOT glowing after about a minute) was fine.

I see a steady ~26VAC signal to the pressure switch.

Other checks:

- air intake/exhaust not clogged (good flow when inducer runs) - inducer motor supply voltage fine (>120VAC) - inducer cap fine (3.0 uF and resistance huge @ DC) - install was years ago so PVC sizing must be right - no backup of water in the drain system - no clogging of the other rubber/plastic tubing (from the pressure switch to the burner box)

So am I at a point where the board is in question or might it still be the pressure switch?

I've tried shorting across the terminals, but an HVAC tech has informed me that not doing it at the proper time or with the connections previously ok (i.e., apparently you can't just disconnect the leads and short the terminals) won't show the proper behavior.

??? HELP!

Thanks

[Zyp]

Why not call a local HVAC service tech. Is it snowing outside? Do you live in Bum-f**k Egypt? Can the local HVAC service tech. make it to your home without trouble? Why monkey with something you clearly don't understand and end up making it worse? A qualified CARRIER service tech., can fix your problem with parts off his service truck and be on his way in less than and hour. I don't see why you're not hiring a qualified serivce tech to fix one of the single most expensive appliances in your home? [And the most dangerous I might add as well.]

[Bubba]

That's a little high. You shouldn't see over 23.9v

huge resistance? That could be a problem. You need little resistance. Install a little resistor.

Yep, if it was installed that long ago, its just GOTTA be right!

I would definitely replace the board. Its gotta be bad.

Have you tried shorting across R and C for 35 seconds?

Bubba