Furnace fan cycles after turning A/C off

[TexasJorge]

I have just recently begun using the A/C daily. Summer is here! Given my location--150 miles from the coast-and my personal comfort levels, I generally run it about 12 hours a day. I cut it off and sleep with floor fans going at nite, and am normally good until noon or so b4 the heat gets uncomfortable. I have just noticed this in the last 4-5 days.

I have two roof top A/Cs that are vented high. At present, I use only the one in the rear of the coach. The furnace is propane fueled and blows into the coach thru floor vents. The gas is turned off at the tank presently.

When I turn the A/C off at the thermostat switch, I have noticed that the furnace fan will cycle in a seemingly random fashion for brief periods afterwards. When I go outside to check, I can confirm it is in fact the furnace as it is venting to the outside.

The inverter is in the baggage hold just forward of that, but it makes a different signature noise when it goes on. I am hooked up to a 50 amp shore station --w/a 30 amp step down.

While the control panel LEDs show off, I'm wondering if the problem is there in the actual thermostat wall unit? When I turn the A/C on auto cool and scale the temp up to shut it off, the fan/floor vents stop blowing.

My first impulse is age/connections, but I don't 'do' electricity well
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Additional tinkering--
I have found several A/C- ECC - ECM questions in the forum centered on the intellitec products. Now I'm trying to prioritize diagnosing the problem to eliminate buying and trying unnecessary parts in the process. I'm in the middle of the S Texas oil patch, and NE of San Antonio is the nearest CW, about 80 miles away. Not much in the way of service options here.

The ECC EM is a model 00-00591-200 mounted in the panel over the refrigerator. The red test diode appears not to be working, if I slide it to either side. I tripped the ECC main breaker earlier today playing with it, but was able to reset it. I am presently using the rear unit only, as I briefly had both running in March and smelled the faint signature odor electrical burning coming from the forward unit/vents. Shut it off and left it alone. I bought a 50 to 30 amp step down and began using the 50 amp hookup then. I thought it was the wall thermostat, but now I'm not sure. Steps in order with a little detail would help.

TJ
98 Pace/Arrow 36L
Ford V10

I haven't been in this very long, and it's my first summer of learning Thanx

[TexasJorge]

Thanx guys. I've tried researching replacement units. The intellitec ECC units are $180 - $200 on ebay. Anyone have any experience with less expensive alternatives? I'd imagine I'm going to have to go with this as a specialty replacement item because of the nature of an RV's electrical system. I've been sliding the temp all up w/o problem -- so far -- daily heat --less humidity factor -- only gets to the mid 90s.
TJ

[garry1p]

I suspect you have a bad thermostat.

Not sure about your thermostat but "normally" the G terminal is for the fan.

You could disconnect the G wire and see if that keeps the fan from running when you turn the AC off.

Disclaimer I am not a HVAC tech.

[Spizzer]

Man, that is a strange one. My first thought from you description...is it possible that your selector switch for heat/air cond is a bit sloppy and when you go from A/C to off, it actually makes contact momentarily on the Heat position making the fan come on? That would explain why it doesn't do it if the A/C is shut off using the temp selector.

Jeff