A/C Stopped after disconnected heater

Might not help.. You see there has to be a source of power to the RELAY on the A/C that turns it on.. I would like to think that when you are in COOL the A/C provides the 12 volts to the t-stat but.... I do not know that for a fact.

I have only worked on 24 volt AC t-stat systems and typically it uses just one source. No matter the mode.

If power source to the thermostat is the issue you might consider buying a digital thermostat that runs on batteries .. they don't cost much and its a common "upgrade" that many RVers do because digital thermostats are so much better than the old Coleman's. Easy install and lots of "how to" threads on the subject.

This is a guess. But the T-stat runs on 12 volts.

NOW.. That might just come from the FURNCE and not the A/C

If so, that's your problem, You removed the T-Stat Power Source

There may e a way to fix it but here is a suggestion

you had two blue wires on that furnace, One of them was 12 volt + the other was the return from the T-Stat

Obtain an automotive test light.. CLip it to a known ground and search for a good 12 volt source (Bright light) now clip it to one of the blue wires (Heck oth of them even and touch it to the 12 volt source, See if A/C now works

IF it does, get a license plate lamp socket (Wedge base) and bulb and make those connections solid.. The lamp will act as a self-reseting breaker if any shorts happen. I use that same system elsewhere in my RV.

I was afraid I broke the circuit some where. The 5 wires I have at the furnace end are red,white,blue,green and yellow.This group seems to run to the lower unit of the AC where there is a plate with 4 screws which has the green,white blue and yellow wire attached to,the red wire is cut about 6" from the plate,there is no tail ends hanging down or attached to any screws.The back of the thermostat has 6 wires soldered to the back and a lot heavier gauge then the regular stat wires.It has all the colors plus a grey wire. Coming out of the wall are 10 wires two sets of the common colors.After looking at the diagrams and then looking at what the factory installed they do not match by a long shot. I have romax wires running on the bottom of the ceiling joists with the ceiling board stapled to the joists making a sandwich of 2 110 lines. Is there any way to run wires from the tstat just to the AC.Also I do not get any power readings on any of the stat lines.

You have 4 wires at the furnace connection. 2 wires (usually blue) go to the wall tstat. The other will be RED (positive) and Ground. On your type system, the 12 volt RED was the power wire to the furnace. ONE of the 2 blue wires was connected to that RED pos wire and THAT blue wire was connected to a 2 wire tstat harness to the wall tstat and THAT was the power to the roof AC. That is why you lost 12 volt power to the roof AC(and tstat) when you removed the furnace. Doug

Moved to Tech Issues forum from DIY.

Yes I checked all the fuses,It has no power to the thermostat.Thank you for the service manual. I tried checking both sides of the fuse terminal and did not get a reading with my multimeter, I also tried the old style test probe that I used years ago to check spark plug wires, alligator clip on one side needle probe on the other,no luck.I will try and trace the connections now that I have a diagram. Again thanks for the advice, this is one of the reasons why I like RV'ers willingness to help others.

The thermostat needs 12 volt power to control the roof unit- the wiring can be found in this service manual, but basically you need to get 12 volt power to the red wire on the thermostat and a ground to the blue wire.

Find the manual for the heater that you removed and look at the wiring schematic to see if that's where the thermostat gets its power.

did you check the little fuse inside the thermastat