I have been working on a friends Sundance Capri (not sure of the age, perhaps around 98 or 01). I have a lot of experience in electronics. It has been not getting to the actual temp. I set it for 101° and it shows 101° but it is actually running about 8-10° colder (93-91°). If I set it higher it over-temps and shuts the heater off. I did get a OH error. The manual states it is over temp. Some online posts indicate an issue with the temp probe.

I checked the temp probe circuit by removing the probe and replaced it with a 20K potentiometer and the circuit card responded correctly so I ordered and changed the temp probe (about $45.00). I installed it and I still have the same problem, however I do not get the OH error.

I checked the old temp probe and the new temp probe and they ohm the same between 18 and 21 ohms depending the actual temp. I have removed the controller and cleaned the contacts on both the card and the temp probe connector and looked at the back to check for rust or any indication corrosion. It looks like there is no calibration on the card for this circuit so any inaccuracy cannot be calibrated out.

The controller card says it is a 850 LCD PWA:850 NT. When I look online for a replacement and was really surprised that they run between $600 and $1200. I hate to order one and eat the cost when most online dealers will not return it if it is not the issue. I was thinking of putting a 20Mohm pot in parallel to make a calibrate the circuit but did not know the input impedance and did not want to overload the card if it was not really the problem.

Any one got any other ideas? If I had the Schematic I could do a lower level diagnostic and change an possible bad resistor or cap in the temp circuit but with out it my hands are a little tied.

Thanks,

Mark