Hi all, I had an E04 code on the Minimax with no flame. After the work below, I get a flame, but the heater now cycles, dropping out of the heating status, and eventually shows E04 again along with the Service light and the Fenwal Ignition module blinks once, which is supposedly an air flow fault, though I've checked the air flow sensor and it it closing when the blower comes on following ignition. I have a troubleshooting guide for an NT and based on my cycle described below, it suggests I likely have a bad ignition module. I wanted to run this by you guys first to see if there was anything else I should check before tracking down a new module.
Here's the cycle I see:
1. 40 sec heat cycle with verified ignition. Heating light is on. I can both hear it and see the flame through the glass porthole. This matches the troubleshooting guide.
2. Blower comes on and I can feel the strong, hot exhaust. I have measured the flame sensor and I get between .02 and .03 milliamps. Voltage at the flame sensor is 94VAC (no flame), 66VAC (flame). Note that my digital multimeter doesn't measure into the singe digit microamp range so my numbers could be iffy this low.
3. After the blower starts, frequently 7 or 8 seconds later the heating light drops out and the cycle starts over. Infrequently, the heating light stays on for a longer period, maybe up to a minute, but it always drops out and the cycle restarts.
After I got the initial error, I decided to do a good overhaul of the heater and see what was bad. So far, I've done the following:
1. Replaced a heavily damaged Ignitor with an OEM. Now I get flame.
2. Replaced a heavily damaged flame sensor with an OEM and replaced the wiring connector to ensure solid connection. The Minimax troubleshooting guide I have is for an NT, not an NT TSI (couldn't fine one for my model) states that there should be 24VAC on the flame sensor probe connection. My FENWAL Ignition is different from that shown in the manual. I have the FENWAL cat no 35-663902-112/Pentair 472150 Rev B. I get 94VAC at the probe and I measure between .02 and .03 milliamps through the sensor when I get a flame.
3. Replaced the start capacitor on the blower as it was rusted badly. The blower seems to work as expected.
4. Removed the burner manifold and cleaned everything. Rust removed. All gas ports and tubes verified clean
5. A couple of years ago, I replaced the Thermistor. It still looks brand new.
6. Checked the Air pressure sensor from the blower. It is working fine.
Here's the cycle I see:
1. 40 sec heat cycle with verified ignition. Heating light is on. I can both hear it and see the flame through the glass porthole. This matches the troubleshooting guide.
2. Blower comes on and I can feel the strong, hot exhaust. I have measured the flame sensor and I get between .02 and .03 milliamps. Voltage at the flame sensor is 94VAC (no flame), 66VAC (flame). Note that my digital multimeter doesn't measure into the singe digit microamp range so my numbers could be iffy this low.
3. After the blower starts, frequently 7 or 8 seconds later the heating light drops out and the cycle starts over. Infrequently, the heating light stays on for a longer period, maybe up to a minute, but it always drops out and the cycle restarts.
After I got the initial error, I decided to do a good overhaul of the heater and see what was bad. So far, I've done the following:
1. Replaced a heavily damaged Ignitor with an OEM. Now I get flame.
2. Replaced a heavily damaged flame sensor with an OEM and replaced the wiring connector to ensure solid connection. The Minimax troubleshooting guide I have is for an NT, not an NT TSI (couldn't fine one for my model) states that there should be 24VAC on the flame sensor probe connection. My FENWAL Ignition is different from that shown in the manual. I have the FENWAL cat no 35-663902-112/Pentair 472150 Rev B. I get 94VAC at the probe and I measure between .02 and .03 milliamps through the sensor when I get a flame.
3. Replaced the start capacitor on the blower as it was rusted badly. The blower seems to work as expected.
4. Removed the burner manifold and cleaned everything. Rust removed. All gas ports and tubes verified clean
5. A couple of years ago, I replaced the Thermistor. It still looks brand new.
6. Checked the Air pressure sensor from the blower. It is working fine.
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