Ok i have a customer that i installed one of the new trane, amer. standard with 19 kw heaters with. The unit has worked like a dream through summer and winter until now. They live far away from me and i am trying to find out if i am correct on my over the phone diagnostic. I have a honeywell visionpro heat pump stat. All is sized correctly and wired correctly. Long story short. The heat pump runs fine, but all my strip heaters in the ahu, seemed to lock out the other day. this includes the emergency heat. I had customer reset line voltage to the unit, and all was well for 5 days. It did it again today. I had customer change the filter!!!!!!!!!!!!!!!!. "totally caked" he said over the phone. Does this ahu have a hard lockout if the strip heaters cycle off of the limit possibly more than once during a cycle. Hence the dirty filter. I have the manual at the job, or i wouldnt be begging for a reply. Thanks in advance.