I finally found the LED Status indicator. It is located on the gas control unit, but it is not visible unless you use a mirror or get your head down on to the furnace support floor. It is below an extended portion of the control just below the thermostat wiring terminals. I would not have found it except for going over the entire furnace interior with my wife’s cosmetic mirror and looking in under and behind every inch of the furnace. There is no way anyone can see it with the lower compartment cover in place. Nowhere near the observation window in the upper compartment cover panel.
The gas controller is an “HSCI Furnace Control” to use with all gasses.
· CAN/CSA-622.2 # XXXXX;
· 1012-940 Model HK42FZo11
Carrier Furnace LED STATUS CODE
Initially I got the code * _ _ Dot Dash Dash = Code 12,
From decal on upper door panel is the following:
Code 12 = “BLOWER ON AFTER POWER UP” (115 VAC or 24 VAC)
Blower runs for 90 seconds, if unit is powered up during a call for heat (Red-White closed).
Next test with ‘lower compartment cover in place switch’ taped closed I got the following code: * * * _ _ _ = 3 dots 4 dashes = Code 34
Code 34 = “IGNITION PROVIDING FAILURE”
Control will try three more times before lockout #14 occurs. If flame signal lost after trial for ignition period, blower will come on for 90 second recycle delay. Check for:
· Oxide build-up on flame sensor (clean with fine steel wool).
· Proper flame sense microamps(.5 microamps D.C. min., 4.0 to 6.0 nominal).
· Gas valve defective or gas valve turned “OFF”.
· Defective hot surface ignitor.
· Manual gas valve shut-off.
· Low inlet gas pressure.
· Control ground continuity.
· Green wire MUST be connected to furnace sheet metal.
· Inadequate flame carryover or rough ignition.
· Flame sensor must be ungrounded.
Test for voltage revealed no AC or DC voltage between “C” (common) and “R” terminals.
I did a more thorough search and found the following:
Found and tested ‘Draft Safeguard Switch,’ it was closed (near zero ohms).
Found the ‘High Temperature Cutout’ (it is not a switch) and inline Fuse; both tested OK (closed with near zero Ohms).
Found that there is only one ‘Hot Surface Ignitor’ (on the right gas burner tube); checked and it has NO continuity (infinite Ohms) between the two leads at the closest connector.
One of my difficulties on this troubleshooting exercise is that I don’t recognize the OEM controls on consumer appliances. They don’t look at all like the “Utility Grade” controls that I was so used to in hydroelectric powerhouses.
Let me know if the open ‘Hot Surface Ignitor’ circuit is the problem. Isn’t it supposed to get hot due to current flow across a resistance? (i.e., Power = I2 * R).
I have NOT yet removed the jumper between 'W' & 'R', let me know if and when I should.