Coleman Mach thermostat

This is my fist time on this site so I hope I can make myself clear the first time. I have a Coleman Mach AC and thermostat in my 29' Wilderness. The system is ducted, and the AC is a Model 833-8664 which is out of production. I keep my trailer a a place I lease about 80 miles away, stays plugged in. A month ago I was there I was there and the unit was working fine. A few days after I left we had some rain and a little rain. When I returned a couple weeks ago I flipped on the thermostat which was in the "off" position. Later on I got my multimeter out pulled the thermostat off the wall and found the fuse blown. Being "stupid" i went to the truck and tried to place a truck fuse in the  holder. It blew immediately of course since it was not designed to fit into the smaller fuse holder. Then I checked the fuses in the power distribution box and found a bad 15 amp automotive fuse bad this time I replaced it with the "right" fuse and it did not blow. The next day I drove into Johnson City and was unable to find a 2 amp fuse so I bought a 3 amp fuse. Got back tried it and it blew, while the thermostat was in the "off" position, the 15 amp stayed good. I know this is long winded but I am trying to give all the info I have.
I think I have a short some where and while RVP has not been much help they did say to look after the thermostat for a short. Someone told me this was a AC fuse since it is physically smaller than a standard 12 volt glass fuse. I bought the only one that RV out here in Georgetown had for 2.00 and being 80 miles away I wanted more so I went to radioshack and ordered some slow blow fuse for spares but now I thing I messed up again (wrong Fuse).
Can one the local experts here help me better diagnosis were my problem is and what kind of use I should be looking for. The fuse I got at RV Outlet was marked 2A250 Volt on one end and BUSSGMA on the other.
All help is appreciated.

Bholt

The Voltage does not mean a lot for your purposes but the AMPS and physical size do!!. When you take the thermostat off the wall, you should find a cable connection (plug) and perhaps a loose wire connection or 3 pin plug. The smaller one should have the 12V supply (12V + ground) for the thermostat and the wire going to the furnace for heat. The bigger (on mine it is a 9 wire cable) goes to the AC unit. Disconnect the larger cable and the furnace lead BEFORE plugging in a new fuse and see if the new fuse holds. If so the problem will be towards the AC unit, or the furnace. (The furnace is not likely to be the problem but... Unfortunately I do not have my books here to check the electrical diagram but I have to go by my memory for MY unit.)

I suspect you may have had 120V power problems while the trailer was plugged in and that may have damaged the air conditioner. You may have damaged the thermostat too by putting in fuses that did not fit correctly and/or blew several times. If so, a new thermostat is in order as well ($$) as these thermostats are easily damaged and not very robust. (I had to replace 3, the original, and 2 new ones until I got a good one. Fortunately the defective new ones were guaranteed.) There is surely a replacement thermostat from Coleman Mach available but not cheap. These can often be replaced with certain after market units such as a Rite Temp or a Hunter model if you are somewhat electrically competent The instructions are readily available on the internet.

The fuse you need is one that is identical to the original one, both in physical size and in amperage. It will have similar, but somewhat different markings to the one you found at the RV outlet. I have never blown that one so never really examined it in detail. You may have to visit an electrical supplier more so than an RV outlet. Worst case: RVP can tell you exactly what the correct fuse is and perhaps supply it (for a price!).

Thanks for the input I am hoping it is just a wire issue got more 2.0 GMA fuses today. If the thermostat is bad, I assume you would recommend going the digital route. looking around there are several but since my analog/manual is a heat/cool with a high/low speed fan do you the  WHITE DIGITAL THERMOSTAT MODEL # AM7855 RV COMFORT 8330-336 COLEMAN MACH is the right one for my unit. here is a link.
http://www.ebay.com/itm/WHITE-DIGITAL-THERMOSTAT-MODEL-AM7855-RV-COMFORT-8330-336-COLEMAN-MACH-/281354884291?pt=Motors_RV_Trailer_Camper_Parts_Accessories&hash=item41820ed4c3&vxp=mtr

bholt

Going the digital route?? Not sure you have much choice today. Not likely a 'wire' issue but....

The only three I have seen instructions for are: Hunter model 42999 or 42995 and RiteTemp 8085C. I would recommend Hunter. Remember these use 12V DC not 24V AC like many home thermostats. For Coleman models, ask RVP and tell them which model air conditioner you have. Looks like the one you picked might work!!

You may loose one fan speed with outside brands in some cases but use auto/high .... or simply add a small switch for the second speed. Fan speed only affects the air conditioner, not the furnace.

After watching a youtube video I think I might just go the hunter route seems pretty simple. For 20.00 I wouldn't mind having one with me just in case the mach is bad, since I will be quite a ways from any town. Thanks again.

OK so I got it fixed. I ended up up getting a tech to come out and diagnose the problem after I found no burnt wires or visible shorts.  Before he came out I ended up frying the thermostat, that is why I ended up finding a technician to diagnose the problem. Since I knew I needed a new thermostat I ordered a coleman just to prevent any further issues. Turns out it was the thermostat. I replaced it and the unit works fine.
I also contacted honeywell and Courtney proved very helpful. She told me that I could use the rth111 or the rth2300 if you are looking for a programmable thermostat.

Hope this helps someone in the future.

B Holt

I have the exact same problem. But I did replace the thermostat to eliminate guess work. Does the controller up inside the ac unit control the heater as well. I'm wondering if so can a bad/faulty controller blow the thermostat fuse.
.