javaseuf wrote: You may be onto something when you mention the 'vacuum" symptom.
It is possible that you have an air leak between your discharge and return sections. These two sections should be isolated in two places. Down in the coach, up inside the access panel on the ceiling and up on the roof where the schroud covers the eveaporator coil. These roof-schrouds usually have foam rubber between the sheet-metal and if the seal is comprimised, you could get a vacuum from the blower wheel (not the fan blade in front of the condensor coil) which could suck condensation back into the unit.
I'll climb up and check that. Not to sound stupid, but you're not talking about the seal between the unit and the MH are you? If so that seal seems to be good.
I had the same problem result, water where it should not be. Had the roof units completely check out, no problems found ... After much head scratching, and by accident, while trying to dry the ceiling, I removed the return air plates and left them off while running the fan on high. The duct work dried along with the ceiling. Thinking about this and what "I" could have done to cause this (the first 3 or 4 years never had this problem. It dawned on me that I had replaced the filter material with some I purchased at my local hardware store, and also remembered reading somewhere to be careful where replacing these filters, to use the same "quality" material so as NOT to restrict the air flow Problem resolved
Ed Alleger
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Leo, IN
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Again, with the inside cover off you should be able to see where the water is coming from. If it stops with the cover off then it might be a filter restriction.
javaseuf wrote: You may be onto something when you mention the 'vacuum" symptom.
It is possible that you have an air leak between your discharge and return sections. These two sections should be isolated in two places. Down in the coach, up inside the access panel on the ceiling and up on the roof where the schroud covers the eveaporator coil. These roof-schrouds usually have foam rubber between the sheet-metal and if the seal is comprimised, you could get a vacuum from the blower wheel (not the fan blade in front of the condensor coil) which could suck condensation back into the unit.
I'll climb up and check that. Not to sound stupid, but you're not talking about the seal between the unit and the MH are you? If so that seal seems to be good.
No, I am talking about the sealant used on the sheet-metal that encloses the evaporator coil. The reason your comment on the vacuum sparked my memory is because I remember I once worked on a unit that I had removed the cover from and the condensate tray was full of water but the drains were not blocked. I could see little waves in the water and when the inside fan was turned off, the water began to drain. It was suction from the evaporator coil area that was interfearing with proper drainage.
Contrary to what other replies have stated, water should never enter the living area with a properly operating unit. Filters, air-flow and fan speed will not contribute to, correct or prevent the trouble.
Very simply, the condensation from the eveporator coil, which is normal, is failing to drain from the inside pan to the outside.
and from your description, it isn't due to a bad seal between the roof and the unit. Your evaporator drain isn't draining.
Steve
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... After much head scratching, and by accident, while trying to dry the ceiling, I removed the return air plates and left them off while running the fan on high. The duct work dried along with the ceiling. Thinking about this 
and what "I" could have done to cause this (the first 3 or 4 years never had this problem. It dawned on me 
that I had replaced the filter material with some I purchased at my local hardware store, and also remembered reading somewhere 
to be careful where replacing these filters, to use the same "quality" material so as NOT to restrict the air flow 
Problem resolved
