dometyic thermostat problem

Well I am not going to disregard the remarks of Chris Bryant and Dougrainer. Have seen these 2 fellows give good advice too many times. I am unable to check the ac fan and furnace for a week but look forward to doing it. The obvious confusion is on my part for believing there was but one fan speed.
Thanks do much for all the comments!

Weldon wrote:
Have used the ac for some time without issue other than the ac would go off and come right back on after reaching the desired temp.
As stated above when it is put on furnace now both ac and furnace come on at the same time. I can use ac but now it will continue to run rather than going off automatic. There are 3 wires connected. Black, orange, red

1. That so called "tech" does not know what he is doing
2. You have a Dometic Single Zone Tstat
3. Depending on the Dometic model AC, YOU WILL HAVE LO OR MED OR HI. NOT one fan speed. Some have just Lo and Hi
4. When the roof AC comes on when furnace selected, the Compressor does NOT come on, only at the AC fan speed you have selected. To STOP the AC fan in furnace mode you go to the FAN setting and select AUTO.
The FAN setting is one of the selectable modes on the tstat. Doug

Have used the ac for some time without issue other than the ac would go off and come right back on after reaching the desired temp.
As stated above when it is put on furnace now both ac and furnace come on at the same time. I can use ac but now it will continue to run rather than going off automatic. There are 3 wires connected. Black, orange, red

Chris, the speed cannot be changed there is no speed control. When the thermostat was installed the tech said there was one speed only.

When you toggle to the fan setting, you can change the speed and whether it is auto or on. I have both the users guide and the owners manual at http://bryantrv.com/owners.html

There is no high or low for fan speed. One simply pushes a button to change from cool to heat to fan. Recently when using the ac it was not totally sensitive to the temp setting. It would cool down to set temp then go off and come back on. it is about 15 months old, was installed when we had the "control box" replaced. Thanks!

put the fan on auto when yiu want to turn the heater on .When running the ac you want the fan on high