I have a Carrier 58PAV that intermittently aborts or sometimes clicks on and off at the draft blower stage. I found out I can move the control board (HK42FZ007) when the blower motor clicks off, and it clicks and comes right back on. If I hold it just right, the furnace starts and if I manage to get the cover back on while its running, it runs for days - but eventually fails again. I've narrowed it down to area of the control board (L1) - a black wire which comes from the front panel switch and the junction box. I can wiggle this wire or the one next to it and the draft blower will kick on and off. I removed the connectors and they seem to fit tight and don't seem to be broken - the posts are solid. Not sure where the bad connection is - any ideas?

A black wire labeled L1 is likely the hot AC wire in. It could be the wire is broken under the insulation, perhaps near the connector. Try holding the wire still near the connector and wiggling it back furthur. If that doesn't seem to cause the problem, try cutting the wire back a ways and replacing the terminal or soldering the end of the wire to the old terminal.

Thanks Labman,
The connector checks out okay. I tried holding the connectors while moving the wires and could not get it to fail. I can hold the module and any connector I pull (around L1) that moves the circuit board triggers the failure.

The interesting thing is that it only fails during the draft blower stage before ignition. During that time I can move the control board and get it to click on and off. Once the gas is burning, moving the control board doesn't cause it to shut down.

Just one other thing - occasionally when it fails, I can hear a faint high pitched sound that seems to be coming from the board.

Sometimes it is hard to move one thing and not another. Maybe pulling on the wire moves the board, breaking a contact. The board has a series of contacts that go in a slot like a computer card? If so, try cleaning the contacts. A pencil eraser makes a good mild abrasive. Ground yourself before touching the contacts on the board. Perhaps post a question in the computer hardware section here asking for instructions to clean contacts on a computer like board. We have some good computer people here.

Wow! I had the SAME problem that you described. High pitch buzzing sound and when I tap the controller board it starts the furnace.

I took the entire controller board apart and found that there was dry solder on several pins. Especially the wires coming from the zone controller. I re-touched the pins with a soldering iron and freshened the solder. It fixed the problems for me.

Rajat

Oh one more thing, the faint high pitch sound is a relay chattering due to the intermittent connection in the dry solder. - Rajat

Had a problem with a Carrier 58PAV070-12 furnace not heating up and flashing LED error code 31. I replaced the glow plug (hot surface ignitor), I replaced the thermostat and added fresh batteries and still no luck. I took out the inducer blower fan to make sure there were no obstructions and to inspect - all was fine. I remvoed the pressure switch and blew into it to make sure the diaphram was still in tact, I also cleared out the hose and pushed throug the small slot where the hose is attached to on the furnace to make sure there were no blockages. STILL NO HEAT!
Finally had an HVAC tech out to the home and he found that upon wiggling the connectors to the furnace control board that he could get the inducer motor to kick on, the glow plug to light up, and finally the burners to start and heat the house. The problem is that after reaching the set temperature on the thermostat the burners would turn off which is fine but they would not light back up even if I increased the thermostat temperature set point. The HVAC tech menitoned that the problem was likely a bad control board. My father-in-law came over to help me tie wrap some of the "suspected" lose connections to the control board which did ignite the burners, but once again, the burners would not light back up after reaching the desired temp.
Thankfully my father-in-law was able to find the identical control board that was in question - part number HK42FZ007. Received it yesterday (December 19, 2011) and installed with my wife's help. We killed the circuit breaker, killed the switch in the garage for the furnace, and turned the gas valve OFF. We then disconnected cables from old control board onto replacement board one by one (but also took detailed pictures prior to doing so that we would not cross any connections). 15 minutes later, the heat was moving through the house!! Tested by letting the termostat reach the setpoint of 70deg which turned off the burners and blower after a few minutes... we then upped the temp to 74 degrees and the furnace worked as expected. The inducer motor kicked on (on this furnace, the inducer motor has a black flywheel fan which is located on the top left hand from the gas valve), the glow plug lit up, the a few seconds later the gas valve clicked on and the three burners were lit. This was an easy fix but just stressful to find the solution. My suggestion is, get a trusted HVAC tech to diagnose, and if you feel comfortable (and no risk to your health or safety), buy the parts and save yourself a couple hundred bucks.
Thanks Dave for ordering the board and thanks Christine for helping me keep the wires straight.