AC / Heater issues

[Mike Camping]

I have been having issues with my AC / Heater since 6 months after purchasing my Sprinter 311BHS in 2012. My most current issue is when the A/C comes on so does the heater. Has anyone experienced this in the past?
The system is an AirExcel heater with a Coleman Mach-3 A/C unit using the Coleman t-stat.

In the past the thermostat cable was replaced under warranty, The A/C top unit went bad last summer and was replaced. I most recently replaced the thermostat. The heater coming on was noticed early last year and may have been doing so for ever. I do not always turn on my LP so I didn't really notice prior to last year.

Any insight or help would be appreciated.

Thanks,

[hankpage]

Check and see if your thermostat's fan setting is on "AUTO". The furnace may not be running, only the fan. JM2¢, Hank

[Tbos]

You may want to contact Chuckster57. He's an RV tech and may have an idea.

[Mike Camping]

Thanks Hank for the advise. The heater unit kicks on when the thermostat calls for the compressor no matter what position the fan Auto/On is at and no matter what position the Lo/High is at. To clarify the heater does not kick on when we have the fan set to on, and works fine in heat mode. For some reason I am getting 6vdc plus or minus on the heater wire from the t-stat when the t-stat calls for the compressor. So far from what I read their can be no voltage on the heater wire from t-stat or it will kick on. I am wondering if I am getting inductance causing the voltage. I beginning to question the warranty work I had done a couple of years ago and whether it was done correctly ie using the correct t-stat cable maybe causing the additional issues since the repair.

Thanks again Hank