Help with HVAC diagnosis

The dumbass tech who worked on my HVAC last time failed to properly secure the panel covering the control board and it got rained on. I’d be super pissed if that wasn’t me, but what can I do? So here’s the issue:

System is a gas-pac/AC with a Nordyne 624631-B control board.
It runs the fire box evac fan constantly whether the thermostat is calling for heat or cold.
Red LED on the board is flashing constantly which my chart tells me is a false flame or a !@#$EDFRGtty short. Chart is partially unlegible.
I’ve pulled the service disconnecct until I can get some idea how to proceed.

Is it safe to hit everything with compressed air to dry it out and hope for a miraculous recovery?

Any pro tips are welcome
@jjwestbrook if you gotcher ears on...

This may or may not be helpful. It appears to be an aftermarket replacement for your Nordyne board, so maybe the fault codes are the same.
http://www.icmcontrols.com/ProdImages/ig_LIAF117.pdf

Gas valve relay short. That was pretty wet... if drying it doesn't work, will unplugging it let me run my ac?

I got this mostly fixed... with my leaf blower. Board, wires, sensors, everything was soaked and I wasn't really happy dragging out extension cords over wet ground to power my compressor. So I turned the leaf blower on it for 10-15 minutes to dry everything out. Worked great and got the AC going again. Heat still doesn't work but I think I have that narrowed down to the flame sensor and I have a few weeks to fix it.

Surprisingly, a lot of times electronics will survive getting wet as long as applied power doesn't short something out and damage it. I would suggest that you continue to monitor the circuit board for signs of corrosion going forward as part of a preventive maintenance program. You don't want it to fail at the worst moment.

Catfish said:

I got this mostly fixed... with my leaf blower. Board, wires, sensors, everything was soaked and I wasn't really happy dragging out extension cords over wet ground to power by compressor. So I turned the leaf blower on it for 10-15 minutes to dry everything out. Worked great and got the AC going again. Heat still doesn't work but I think I have that narrowed down to the flame sensor and I have a few weeks to fix it.

Click to expand...

If the unit will not fire it’s not the flame sensor.

1. When in heat mode does the combustion fan come on. It is the little blower which expels air outside the unit. Last week I checked a unit that had water in the combustion fan blower assembly. Although the motor was turning the blower wheel it never allowed the pressure switch to activate indicating the blower was active.

2. Combustion motor starts first and runs for 30 seconds to purge any gas. Once it starts a hose on the bottom of the blower housing (usually red or orange) pulls in a set of contacts on a pressure switch which tells the board the combustion motor is active.

3. Next the igniter or glow coil starts. Then the gas valve energizes allowing gas thru the orifices to fire the unit.

4. After the gas flames a flame sensor tells the board you have a constant flame. If there is no flame then the sensor shuts down the unit.

5. The unit will attempt to start three times. If it is unsuccessful after 3 attempts it will initiate a hard lockout not allowing it to try again.

6. To override the lockout which occurred after 3 failures you simply pull the power disconnect for a few seconds then restore power. This should only be done if you are troubleshooting the issue. Otherwise call a tech or a jackass who will change all the parts until it works.

7. Is there gas in the tank or coming from the natural gas line?

Note: 1st thing I would do is cut the power off to the unit and take the six bolts off the combustion blower assembly. Pull the wires off the plastic connector. The connector is keyed to go back in only one direction so don’t worry. Pull the little hose off the blower housing. Turn the assembly upside down and drain any water that may be in it. Inspect the blower wheel to make sure the wheel has not rusted out. Reinstall every thing and power the unit back on.

Visually watch the unit attempt to fire. Combustion motor comes on. Little later igniter (like sparker or glows). Is the a flame? Yes or no. Yes- flame sensor, no- board, valve, igniter.

Thanks for the breakdown. Steps 1, 2, 3 = ok. At step 4 I get a visible flame but the unit kicks off anyhow after a few seconds, which is why I suspect the sensor.

I'll get in there this weekend and make sure all the pieces and parts are dry.

Catfish said:

Thanks for the breakdown. Steps 1, 2, 3 = ok. At step 4 I get a visible flame but the unit kicks off anyhow after a few seconds, which is why I suspect the sensor.

I'll get in there this weekend and make sure all the pieces and parts are dry.

Click to expand...

use a dollar bill ( sandpaper is too rough ) to clean the flame sensor also make sure the wire connection at the board is tight