Thermostat Upgrade Problem

[cruzin101]

Originally Posted by Fish and Dear

I have a Coleman Mach ducted AC and the standard Suburban furnace. The OEM thermostat is a Coleman 7330 series analog unit that gives us fluctuations in temps I cannot stand. I looked up the direct replacement part for it and got the Coleman 8330 digital series that is listed as the direct replacement for Fan/Air/Furnance. We do not have a heat pump.

I disconnected all coach power and verified it. I cut and connected only 1 wire at a time, so I did not have to worry about mislabeling things. I took pictures of each OEM wire connection, and as I made the new connections one at a time I verified the wiring is the same.

Power back on to the coach and nothing at the thermostat. It does not come on in any mode. Nothing at all on the screen. Coach breakers and fuses are all good.

Any suggestions??

Can you send me a pic of your Oem wiring? Cruzin101@comcast.net

[cruzin101]

Originally Posted by javelin

MTHook, look back near the beginning of this thread and look at the diagram I posted of my thermostat conversion to a Hunter Digital. All basic thermostats have similar designations and normally +12 VDC is connected to the R terminal and for basic RV furnace and air conditioner the R and RC connectors are connected together with a jumper. If your thermostat runs on its own AA batteries you should not require a ground connection; but if it uses the coach battery for power you will require a ground wire too (B terminal usually). I am not sure why your diagram says battery to G terminal as that usually is to provide power from the thermostat to either high or low speed fan on the air conditioner via the switch you show. To air conditioning compressor for call to cool (Y); to Furnace for call to heat (W). Hope that helps you out.

Unfortunately I wasn’t able get a pic of my thermostat as originally wired. As I pulled the wiring thru the wall the wire caps came off all but one wire. I tried matching the coach wires to the appropriate color on the thermostat but nothing works . Any advise on identifying the coaaach wiring would be appreciated

[ducksface]

http://www.thorforums.com/forums/f28...run-18996.html
I think it's post 93. In it is pictures of my thermostat wiring wired to the original Thor thermostat and then pictures of the wall wiring wired to the new digital thermostat.
Maybe the colors in your wall will match the colors in my wall.

Or

It might be time to call and ac guy and ask if 30 bucks will cover if you drive over to his shop.
Hell, the ac guy you use for your house might do it for free.

[cruzin101]

Originally Posted by ducksface

http://www.thorforums.com/forums/f28...run-18996.html
That thread is 200 posts long, but in it is pictures of my thermostat wiring wired to the original Thor thermostat and then pictures of the wall wiring wired to the new digital thermostat.
Maybe the colors in your wall will match the colors in my wall. It shouldn't take you five minutes to look through the pictures and find the thermostat post.

Or

It might be time to call and ac guy and ask if 30 bucks will cover if you drive over to his shop.
Hell, the ac guy you use for your house might do it for free.

I would love to see those pics if you can send them to cruzin101@comcast.net . Otherwise I will be calling my local ac/heat folks😱

[ducksface]

Just click the link and then go to post 93.
The pictures are right here on this forum.

(and get your email address off of the post. The spam and porn you'll get....)

[javelin]

Originally Posted by cruzin101

Unfortunately I wasn’t able get a pic of my thermostat as originally wired. As I pulled the wiring thru the wall the wire caps came off all but one wire. I tried matching the coach wires to the appropriate color on the thermostat but nothing works . Any advise on identifying the coaaach wiring would be appreciated

Well because of “Murphy’s Law” probably the thermostat feeder wire colors “inside the wall” don’t match the wire colors (via the wire nuts you accidentally pulled off originally) that physically connect to the thermostat itself. So you have reconnected the new digital thermostat by best guessing re-connections inside the wall, but nothing works.

It is possible that you blew a fuse on the 12vdc feed wire when you pulled off the wire nuts originally as you removed the old analog thermostat. So get out your trusty voltmeter and try to find the +12vdc wire. It normally connects to the R terminal(s) on the thermostat (sometimes there is a connection shorting strap between two R terminals if equipped). The B terminal is usually the ground connection terminal inside the thermostat (if the new digital thermo still uses it; some digitals use their own internal AA batteries instead so don’t require a coach ground to operate).


If none of the thermostat wires read/measure +12vdc then you will have to find the reason why.....(find the fuse that has blown.....”might” be inside the furnace via its outside access panel – or since the furnace feeds the thermostat with 12vdc it might be the fuse feeding the furnace). It also might be wise to disconnect all wires at the thermostat temporarily (except the one you said did not accidentally disconnect in the wall originally – I assume it is connected correctly still) and keep the bare wires apart (not shorting). When you find/repair the 12vdc fuse (if necessary), then determine which thermostat wire it is and connect that wire to the R terminal on the thermostat. This 12vdc is the power the thermostat connects through its mini relays to turn on the other devices/relays like the furnace; air conditioner compressor control relay; fan (hi/lo) etc. The key is your power wire as a start.......and ground wire to B if the digital coleman mac uses one. B wire is typically blue but you can't guarantee that here. Hope that helps a bit.

[cruzin101]

Thanks ! I will check my system against your pic tomorrow. If it doesn’t work out for my rig I will be calling the local ac/heat guy.

[cruzin101]

Originally Posted by cruzin101

I would love to see those pics if you can send them to cruzin101@comcast.net . Otherwise I will be calling my local ac/heat folks😱

Looks like I will be making that phone call tomorrow.

[16ACE27]

Originally Posted by cruzin101

Looks like I will be making that phone call tomorrow.

Did you look at the other thread?

http://www.thorforums.com/forums/f27...ade-10711.html

[ducksface]

Originally Posted by cruzin101

Looks like I will be making that phone call tomorrow.

That's not enough of an explanation to be helpful to anyone in a similar bind.

Did the colors not match up?
Did you check the fuses to make sure you still have 12v where it should be?
Did you try the ac when it was too cold outside to kick in?
Did you try just the fan and not ac or heat?
What happened?

And once it's wired correctly, post a picture here for the next guy.
Maybe I'll do a compilation thread of wiring pictures we find.