LT400 Laars heater - fan won't come on

Feb 11, 2015
2
Ft Worth, TX
Greetings - I am trying to get my Laars LT400P-L pool heater going again. It used to work, but has not been used in 3-4 years (house rented out). The pool has been in use the whole time. When I turn on the heater (on spa or pool setting) nothing happens for about 2-1/2 minutes and then I get error lights "Service" and "air flow". The service diagnostic guide mentions the tubing - not an issue as fan won't come on. For fan not operating - it says correct the fault. I isolated the fan and put power on it and it works fine. What should I check next to see why the control circuit will not power up the fan?
 
Welcome to TFP!

It sounds like the next step is to track back the fan power and see where it fails. My guess is that there control board is sending power to the fan, but the wire is not intact, though that is just guessing. Animals sometimes nest inside heaters and chew up the wiring.
 
Welcome to TFP!

It sounds like the next step is to track back the fan power and see where it fails. My guess is that there control board is sending power to the fan, but the wire is not intact, though that is just guessing. Animals sometimes nest inside heaters and chew up the wiring.



Thank you for the welcome message! I checked the wiring for the motor and followed it back to the ignition controller (Fenwal) Not sure how to determine if the lack of fan power is because of a problem in the ignition controller itself or if the electronic controller is not telling the ignition controller to come on. Will have to sit out there with my meter and diagram and wrestle with it some more.
 
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