There's an error LED flashes which indicates an air pressure issue. The blower fan keeps running at the low speed when the system is on, which is pretty strange. For a normal system, at the start up the blower fan should run at at full speed for 15s (pre-purge period), then slow down to half the speed to allow trial ignition for 7s (heating up process). After the flame is detected, the blower fan comes back to the full speed until the heating process is done.
I shorted the air switch outputs to deceive the DDTC that the air pressure was right. Then I heard several clicks inside the DDTC which I guess to change the blower fan speed or for ignition. But there's no ignition happened.
At this moment, I'm not sure if it's the DDTC does not provide the right signal or power for the blower fan to run pre-purge (full speed), or the blower is broken and can only run at the half-speed. The input DDTC seems right as I can measure a 24V presented at the TH pin.
I also changed the running cap of the blower. No luck.
Any suggestion, please?
I shorted the air switch outputs to deceive the DDTC that the air pressure was right. Then I heard several clicks inside the DDTC which I guess to change the blower fan speed or for ignition. But there's no ignition happened.
At this moment, I'm not sure if it's the DDTC does not provide the right signal or power for the blower fan to run pre-purge (full speed), or the blower is broken and can only run at the half-speed. The input DDTC seems right as I can measure a 24V presented at the TH pin.
I also changed the running cap of the blower. No luck.
Any suggestion, please?