I donít know what caused the problem... I donít know how to fix the problem...
but at least I know what the problem is:
The two main t-stat wires are shorted inside the wall.
In order to assist anyone else who may encounter this problem, Iíll describe my troubleshooting process.
First off, the service manager at a local RV dealer (my thanks to RV Lifestyles) assured me that the whole control system is 12v and that I donít need 115v to reset the t-stat. He said it sounded like a wiring problem.
Before buying a mechanical t-stat to get me though the night, I pulled out my multimeter (is it works, it must be a Fluke) and tested the wires.
This was my troubleshooting process:
Trouble Shooting E1 Error on Thermostat
Initial symptoms: although the tstat is set for heat, nothing happens.
Initial troubleshooting steps:
Action: disconnected the three wires in the tstat and reconnected
Result E1 error (communications error)
Action: followed the reset procedure (set tstat to off, depress ď+Ē and ďon/modeĒ at the same time until ď- -ď appears
Result: ď- -ď is displayed
Action: turn tstat to on (either heat or cool)
Result: E1 error recurrs
Action: replace tstat
Result: still get E1 error after reset
- pull intake grate from a/c, pull out the reply/control box and disconnect the four wire tstat jack
- Check continuity between molex jack and tstat
Information: There are three terminals on the tstat:
- right is labeled GND has a 16 awg black wire)
- middle has no label (also has a 16 awg black wire but of a different type)
- Left is labeled +12V (has a 16 awg red wire of the same type as the black middle wire
- Later examination of the wires to the middle and left terminal show they are from a two wire ribbon (ie zip cord)
- Red wire on molex jack is labeled ď+12v from supplyĒ
- Black wire on jack is labeled ď-12v from supply and to t-statĒ
- The two wires above are measured at 13.3V
- Red/ white wire on jack is labeled ď+12v to t-statĒ
- Orange wire is not labeled
- The two wires above are spliced to small gauge wires in what appears to be tstat cable. Note: this is not the same wire as at the middle and left wires at the t-stat. The wires at the tstat are of higher gauge ribbon wire.
Results of continuity tests after disconnecting wires from tstat
- Red/white wire on jack is continuous with both black and red wires of the ribbon cable (ie middle and left terminals of tstat)
- Orange wire on jack is continuous with both black and red wires of the ribbon cable (ie middle and left terminals of tstat)
- Red/wire wire in jack is continuous with orange wire
- Black and red wires of the ribbon cable (ie middle and left terminals of tstat) show as continuous
- Red wire on jack
Conclusion: the wires the go to the middle and left terminals of the tstat must be shorted.
I wired the t-stat directly to the control box and the furnace works fine. No E1 error. Although it dangle from the ceiling at least I have a thermostatically controlled furnace.
Now I have to figure out how to fix the wiring sorry inside the wall.