I have a mobile catering/vending rig built in 2012. It has a Coleman Mach 15K A/C unit for keeping us cool while cooking/serving.Up until a couple of weeks ago, it has been perfectly fine - I use a Honda EU6500is series generator to handle everything in our trailer from fridge, to A/C to warming units and have never had a problem with overloading the generator at all.A couple of weeks ago, I setup like normal and every time the A/C would kick on - the generator would show overload and shut off A/C current. When I moved a few items off to a second generator all was fine, but the EU6500 was running like it had some crazy load attached to it - which it didn't.I thought maybe something had happened to our trusty EU6500, so I purchased a Yamaha generator (EF3000iSEB). (not meant to 'replace' the Eu6500 - just as a secondary backup and as a smaller use generator for when I don't need to run steam tables etc - like when I'm catering - instead of lugging around the beast I can bring this and have 30A service for lighter cooks/jobs.) I tried using it this weekend on the 30A circuit and was only running some lights and small stuff and the Coleman A/C. The minute the A/C tried to kick on - man it looked like a poltergeist had moved in to the trailer - lights flickering (fluorescent) and it killed my kill-a-watt meter. So I re-adjusted (since the show had to go on because I was catering) and got some power from an outlet (20 amp) and moved everything off the Yamaha to shore power except for the A/C - now when the A/C would kick on the generator would run full tilt when I know it only needs like 18A or so to 'run' (I realize the need for more when it's starting..) - but I have one of the EMS-HW50C units installed, so I've seen in the past when on 50A 220V shore power how many amps I pull when operating etc.So I think and am pretty sure, something is going on with the Coleman A/C unit because the problems only arise on both generators, when the A/C unit kicks on. any ideas of where I should turn or try to look to fix this? I'm NOT a mechanic, but if it's just a part to replace/check - I can get that done. If not - I don't want to get screwed for a new A/C unit if I take it in to be looked at. Any help/ideas would be much appreciated!Thanks!

If its dirty and clogged up, it will draw A LOT more power trying to run and cool, I would get up on the roof and remove the shroud and check that its not full of leaves, dirt, dust, or a big one in my area cotton from the cotton wood seeds.I have to clean out the AC wall-units in my house yearly or they will start doing the same thing (drawing too much power popping their breaker) from all the cotton wood crud in them.

I'll take the shroud off and peek - I'd be surprised if it's too dirty as it's stored in a lot with no trees etc - but then again, I've been surprised before!Thanks for the input and idea! I appreciate it! If it is dirty, can I just hose it off? I've never cleaned one before.Keep em coming if you have ideas - thanks!!

A bad capacitor can make an AC operate like Jack Nicholson had the wheel. Check starting current of BOTH the compressor AND the motor that powers the condenser and evaporator fans shaft.Manufacturers should be FORCED TO make the so-called "Hard Start" capacitor standard equipment. OEM can buy stuff for about 20% of what we mortals are forced to pay.

vexter0944 wrote:I'll take the shroud off and peek - I'd be surprised if it's too dirty as it's stored in a lot with no trees etc - but then again, I've been surprised before!Thanks for the input and idea! I appreciate it! If it is dirty, can I just hose it off? I've never cleaned one before.Keep em coming if you have ideas - thanks!!Since you say its a catering/vending rig, you could be dealing with grease or food particulate build up (especially if there's a roof exhaust vent near the AC unit), might not just be tree debris, that's just whats common for me ;)Yeah, I would pick any loose crud out of it by hand, and hose out the rest on the roof side (carefully, I wouldn't go overboard, I don't know how tightly your's is sealed), on the inside I would check the filter (probably washable kind) to be sure its clean as well, any kind of obstructions on condenser or evaporator coils can cause issues with overheating and overloading.

MEXICOWANDERER wrote:A bad capacitor can make an AC operate like Jack Nicholson had the wheel. Check starting current of BOTH the compressor AND the motor that powers the condenser and evaporator fans shaft.Manufacturers should be FORCED TO make the so-called "Hard Start" capacitor standard equipment. OEM can buy stuff for about 20% of what we mortals are forced to pay.Is there a way someone like me, with only a multimeter can check this and if so, how? Otherwise, should I just take it to a shop to have this checked?

Coleman Mach 15000 BTU A/C Issue - Electrical in Nature

29 Replies

j-d
Explorer II
Sep 06, 2014
Every appliance parts store/HVAC parts store in town should have these parts. That said, many don't want to sell to DIY customers. The ones that do, sometimes charge more. Price these on Amazon below, and they're in the $15-20's range except the 5-2-1 they're really proud of. I bought a 45 run cap at "retail" in FL and paid over $50. A SUPCO device in AK cost $50. Both at over-the-counter retail parts stores. But I had the systems running "same day" and didn't hire a tech. If you happen to have AMAZON PRIME, you can have the parts on your doorstep well before your next weekend testing opportunity.

Run Capacitors Some of these are "45+5" combo capacitors in which case you would connect only one side, the "45", to test Compressor Run. 45+5 seems to be more common than the one "45+7.5" listed on Amazon. The 45+7.5 could replace both your COMP/HERM and FAN Run Caps.
5-2-1 Start Kit for 1-3-Ton A/C
that's if you believe the 5-2-1 is better than the more popular
SUPCO SPP6e

To do the testing I suggested, you can start by plugging into a robust 120VAC Shore Tie and simply disconnecting your Start Assist as I noted in the long troubleshooting routine. But then if it fails to start on Shore Tie, you need a "45" capacitor to continue testing.

Personally, RV A/C is so important to us that I have a spare 45+7.5 RUN Cap and a SPP6e Start Assist kit on board. Yeah, about $40 tied up in the two parts, but I can either save a camping trip or a several hundred dollar service call.

Finally subscribed so I'll be sure to see your next reply.
vexter0944
Explorer
Sep 03, 2014
j-d wrote:
Good Pix! You have separate RUN Capacitors for Fan and Compressor. The 7.5@370-VAC is Fan and the 45@370 is Compressor (sometimes called HERM for the hermetically sealed part which is the compressor and coils). If you replace either of those, you can use xx@440-VAC as well. You can go UP on capacitor rated voltage just not down.

Picture your photo of the yellow wiring diagram turned 90* to the Left so it's right-side-up. The dotted-line box on the Left side of the diagram shows an optional Start Assist with a PTCR device. THAT IS WHAT YOU HAVE INSTALLED. A SUPCO SPP6 would be equivalent. The dotted box in the middle shows a Start Assist also, but with Potential Relay. That is the better system. That device called "5-2-1 Compressor Saver" is an aftermarket Potential Relay system. The SUPCO SPP6e "E-Class" approximates what a Potential Relay does, just not quite as well.
OK, starting... If you don't have too low a voltage or insufficient amperage (including too light a power/extension cord), it is of course possible your compressor is failing. More likely:
1. RUN Capacitor is Bad
2. PTCR or Start Capacitor is Bad
I'd say, IF you're at a good power source,
1. Disconnect Power
2. Short across Start Capacitor (the plastic one)
3. Short across Compressor Run Capacitor (the 45 one)
4. Remove the Red and Yellow Wires from the Compressor Run Capacitor that lead back to the Start Assist (black Capacitor with that little PTCR cube. Be sure they don't get against any other terminals.
5. Restore Power
6. Start A/C
7. Starts Better? Discard Start Assist Capacitor and PTCR. Replace with 5-2-1 or SPP6e starting at Step 1
8. Still Starts Poorly? Start at Step 1 and Replace 45@370 with a new 45@370 or 45@440 capacitor
9. Repeat A/C test starting Step 5
10. Better? GOOD. At this point you can re-connect Start Assist and try again. You may or may not notice a quicker start, probably won't unless you get to a generator or lower voltage/amperage shore tie. OR, you can upgrade to 5-2-1 or SPP6e. I would not settle for another PTCR Start Assist like SPP6 if I was replacing a bad one.
11. Report Back!
12. Happy Weekend!

Where is a good place to buy these parts? A quick search yields mostly ebay, but I'm not sure what part numbers I should be using to search.

Thanks again - too much rain/weather to have worked on it over the weekend, hoping to work on it this week.
vexter0944
Explorer
Aug 31, 2014
j-d wrote:
Good Pix! You have separate RUN Capacitors for Fan and Compressor. The 7.5@370-VAC is Fan and the 45@370 is Compressor (sometimes called HERM for the hermetically sealed part which is the compressor and coils). If you replace either of those, you can use xx@440-VAC as well. You can go UP on capacitor rated voltage just not down.

Picture your photo of the yellow wiring diagram turned 90* to the Left so it's right-side-up. The dotted-line box on the Left side of the diagram shows an optional Start Assist with a PTCR device. THAT IS WHAT YOU HAVE INSTALLED. A SUPCO SPP6 would be equivalent. The dotted box in the middle shows a Start Assist also, but with Potential Relay. That is the better system. That device called "5-2-1 Compressor Saver" is an aftermarket Potential Relay system. The SUPCO SPP6e "E-Class" approximates what a Potential Relay does, just not quite as well.
OK, starting... If you don't have too low a voltage or insufficient amperage (including too light a power/extension cord), it is of course possible your compressor is failing. More likely:
1. RUN Capacitor is Bad
2. PTCR or Start Capacitor is Bad
I'd say, IF you're at a good power source,
1. Disconnect Power
2. Short across Start Capacitor (the plastic one)
3. Short across Compressor Run Capacitor (the 45 one)
4. Remove the Red and Yellow Wires from the Compressor Run Capacitor that lead back to the Start Assist (black Capacitor with that little PTCR cube. Be sure they don't get against any other terminals.
5. Restore Power
6. Start A/C
7. Starts Better? Discard Start Assist Capacitor and PTCR. Replace with 5-2-1 or SPP6e starting at Step 1
8. Still Starts Poorly? Start at Step 1 and Replace 45@370 with a new 45@370 or 45@440 capacitor
9. Repeat A/C test starting Step 5
10. Better? GOOD. At this point you can re-connect Start Assist and try again. You may or may not notice a quicker start, probably won't unless you get to a generator or lower voltage/amperage shore tie. OR, you can upgrade to 5-2-1 or SPP6e. I would not settle for another PTCR Start Assist like SPP6 if I was replacing a bad one.
11. Report Back!
12. Happy Weekend!

Thanks for the EXTREMELY detailed plan of attack! WOW. That's awesome!

I'll try to get to this asap - as I live in Midwest, we have a lot of rain over this weekend, so I'll try to get to it - I'll let you know when I do and what happens. Thanks SO much!
NinerBikes
Explorer
Aug 30, 2014
j-d wrote:
Good Pix! You have separate RUN Capacitors for Fan and Compressor. The 7.5@370-VAC is Fan and the 45@370 is Compressor (sometimes called HERM for the hermetically sealed part which is the compressor and coils). If you replace either of those, you can use xx@440-VAC as well. You can go UP on capacitor rated voltage just not down.

Picture your photo of the yellow wiring diagram turned 90* to the Left so it's right-side-up. The dotted-line box on the Left side of the diagram shows an optional Start Assist with a PTCR device. THAT IS WHAT YOU HAVE INSTALLED. A SUPCO SPP6 would be equivalent. The dotted box in the middle shows a Start Assist also, but with Potential Relay. That is the better system. That device called "5-2-1 Compressor Saver" is an aftermarket Potential Relay system. The SUPCO SPP6e "E-Class" approximates what a Potential Relay does, just not quite as well.
OK, starting... If you don't have too low a voltage or insufficient amperage (including too light a power/extension cord), it is of course possible your compressor is failing. More likely:
1. RUN Capacitor is Bad
2. PTCR or Start Capacitor is Bad
I'd say, IF you're at a good power source,
1. Disconnect Power
2. Short across Start Capacitor (the plastic one)
3. Short across Compressor Run Capacitor (the 45 one)
4. Remove the Red and Yellow Wires from the Compressor Run Capacitor that lead back to the Start Assist (black Capacitor with that little PTCR cube. Be sure they don't get against any other terminals.
5. Restore Power
6. Start A/C
7. Starts Better? Discard Start Assist Capacitor and PTCR. Replace with 5-2-1 or SPP6e starting at Step 1
8. Still Starts Poorly? Start at Step 1 and Replace 45@370 with a new 45@370 or 45@440 capacitor
9. Repeat A/C test starting Step 5
10. Better? GOOD. At this point you can re-connect Start Assist and try again. You may or may not notice a quicker start, probably won't unless you get to a generator or lower voltage/amperage shore tie. OR, you can upgrade to 5-2-1 or SPP6e. I would not settle for another PTCR Start Assist like SPP6 if I was replacing a bad one.
11. Report Back!
12. Happy Weekend!

This should be made a sticky, moderators.
j-d
Explorer II
Aug 30, 2014
Good Pix! You have separate RUN Capacitors for Fan and Compressor. The 7.5@370-VAC is Fan and the 45@370 is Compressor (sometimes called HERM for the hermetically sealed part which is the compressor and coils). If you replace either of those, you can use xx@440-VAC as well. You can go UP on capacitor rated voltage just not down.

Picture your photo of the yellow wiring diagram turned 90* to the Left so it's right-side-up. The dotted-line box on the Left side of the diagram shows an optional Start Assist with a PTCR device. THAT IS WHAT YOU HAVE INSTALLED. A SUPCO SPP6 would be equivalent. The dotted box in the middle shows a Start Assist also, but with Potential Relay. That is the better system. That device called "5-2-1 Compressor Saver" is an aftermarket Potential Relay system. The SUPCO SPP6e "E-Class" approximates what a Potential Relay does, just not quite as well.
OK, starting... If you don't have too low a voltage or insufficient amperage (including too light a power/extension cord), it is of course possible your compressor is failing. More likely:
1. RUN Capacitor is Bad
2. PTCR or Start Capacitor is Bad
I'd say, IF you're at a good power source,
1. Disconnect Power
2. Short across Start Capacitor (the plastic one)
3. Short across Compressor Run Capacitor (the 45 one)
4. Remove the Red and Yellow Wires from the Compressor Run Capacitor that lead back to the Start Assist (black Capacitor with that little PTCR cube. Be sure they don't get against any other terminals.
5. Restore Power
6. Start A/C
7. Starts Better? Discard Start Assist Capacitor and PTCR. Replace with 5-2-1 or SPP6e starting at Step 1
8. Still Starts Poorly? Start at Step 1 and Replace 45@370 with a new 45@370 or 45@440 capacitor
9. Repeat A/C test starting Step 5
10. Better? GOOD. At this point you can re-connect Start Assist and try again. You may or may not notice a quicker start, probably won't unless you get to a generator or lower voltage/amperage shore tie. OR, you can upgrade to 5-2-1 or SPP6e. I would not settle for another PTCR Start Assist like SPP6 if I was replacing a bad one.
11. Report Back!
12. Happy Weekend!
vexter0944
Explorer
Aug 30, 2014
Here's the pics - let me know where to go from here. By the way - getting that shroud off as a one man show on a 10 ft ladder is NOT my idea of fun. LOL..

Trailer AC Pics
vexter0944
Explorer
Aug 28, 2014
Ok - tried to get the shroud off tonight to look at it - with 8' of ladder and 6'2 of me - couldn't reach the 2nd screw - only one of them...argh!

I'll have to borrow a taller ladder to get this bad boy - but I'm still working on it. We'll be in touch!
vexter0944
Explorer
Aug 26, 2014
ryanw821 wrote:
I am subscribed here too, I want to know the outcome as well ;)

Right on! Me too - LOL! I'm still shooting to take the trailer to my parents house over the weekend and tear into it. I'll make em some BBQ for the help :)
ryanw821
Explorer
Aug 26, 2014
I am subscribed here too, I want to know the outcome as well ;)
vexter0944
Explorer
Aug 26, 2014
j-d wrote:
Been watching this and for some reason it didn't come up "new post" so I'm glad I looked. Looking forward to the results.

Thanks for keeping en eye on me - I appreciate it much!

Forum Discussion

Coleman Mach 15000 BTU A/C Issue - Electrical in Nature

29 Replies

About Technical Issues

Related Content

Electric

Electrical assistance

Electrical outlet issues

Coleman

Surge or electric brakes