Coleman Mach 15 not blowing cold

[@miscellaneousHandle]

i wish you had made this video last year when my Mach 15 died. i too ended up replacing the whole unit. it was only three years old

[@mikmaster63]

Ya, unfortunately replacing the top unit when it goes bad is the best way. In my market I’ve never seen anyone recharge one of these units successfully. Doesn’t mean there’s not somebody out there that can, I never seen it.

[@guttermastersplus5613]

Very good video great information I had the same problem compressor not working I'll go through mine and see if I can't get it working

[@danielmanly4793]

Excellent video - A+

[@Kevin-zc8pn]

Is the 24 volts coming from the board inside the discharge air? I have 110v to that board where the tstat hooks up but no 24v. Thanks

[@mikmaster63]

Not sure I understand the question. That is a 12 volt system not 24 on the low side. 120 volt is from the board to the upper unit.

[@mikmaster63]

On this unit the 12 volts comes from the t stat. So, if you turn the t stat to high fan you should have 12 volts on the gh input at the board, for example

[@Josh-r3r9r]

So I had this issue as well, checked all power and wiring and everything was good, swapped out the t stat with the front ac t stat and the ac started to blow cold. So that would mean that the rear ac t stat is not working right?

[@mikmaster63]

From where I’m sitting I would say yes. I would put the rear stat on the front AC and see if the front one doesn’t work. If it does work at the front then it may have been a loose connection…

[@xjrockrawler]

Great video! I’ve got power everywhere you checked. But I’m only pulling 6.1 amps. You suggested low refrigerant? Any way to charge it. I’m still under warranty but have a drive to a dealer. Thank you sir

[@mikmaster63]

Thanks. We don’t charge them where I work. I don’t think the manufacturer recommends recharging either. We replace the upper unit.

[@connorshipman9956]

Very informative. Thanks. Is there a way to bench test an AC like this one to see if everything works?

[@mikmaster63]

I’ve never done it but I know techs who have. You would have to have a good 120 volt power source and a 12 volt source. You may need a thermostat depending on which model AC you are testing.

[@tlegends6482]

The 2A fuse in my thermostat keeps blowing when I turn the ac on. The fan and heat pump work just fine; it only happens on cool. The thermostat and the AC unit are both brand new. Only thing that stayed from the old system was the Ac control box. The first trip I took with the new unit was successful. Had nice cold air and no issues. The second trip didn’t go as smooth.. it immediately blew the 2A fuse when I tried to run the ac. I replaced the fuse a few times but no luck. I waiting and tried again the next day… it worked. I had nice cold air for about an hour before the fuse blew again. The RV was plugged into 50A service at the time. Any ideas on what the issue might be? Thank you

[@mikmaster63]

My 1st thought is a shorted thermostat wire. I have seen just one wire in the t stat wire shorted. Disconnect the t stat wire from both ends (make sure you document where they go, and shorts can be intermittent ) then using ohm setting on a meter, see if any of the wires are shorted to ground. Starting at 1:00 mark explains a little bit about t stat wiring. It doesn’t show how to check for a short because that’s not what this video is about. That’s my best guess from here and good luck…

[@tlegends6482]

@@mikmaster63 I’ll give it a shot. Thank you!

[@simaii820]

I just brought a coleman 48004-066 mach 15 with hp. Which control unit do i need to pair this with? Is it 9530a751? And how would i wire the white? Do i wire the heatpump wire from the thermostat to the white on the control box? Can get the fan and furnace to work. But not the compressor or heatpump. Won't turn on. Brand new ac just brought 1 week ago

[@mikmaster63]

The white wire from the thermostat goes to the furnace. Typically in an RV it’s a 12 volt/propane furnace. The other info I’ll have to look into. What I see online is the 9530a751 is for heat pump model. I did work on a heat pump model today and the thermostat was different from what I’m used to seeing on a non heat pump model. I wasn’t working on the heat pump portion so I don’t know off the top of my head what you need. I do see DIYers wire these incorrectly frequently…

[@mikmaster63]

Sorry my parts department couldn’t answer the question and Coleman hasn’t returned my call. I did see on the t stat I’m working on the white wire with the black tracer is heat pump signal. Labeled WHP

[@simaii820]

Thanks again. I just placed an order for 9530a751. And going to wire the whp to white on the control unit when it comes.

[@JKLee-kd6xw]

The air conditioner works, but it doesn't cool. What should I check?

[@mikmaster63]

When you say it works??? Is it blowing air but the air isn’t cold??? I believe this video is pretty thorough on what to check…

[@fbuffy28]

Where did you get the manual reference/shown in the video?

[@mikmaster63]

I bought it a long time ago

[@mikmaster63]

You can get training manuals from Rvti.org I’m not sure if they are using the same training manuals that I’ve seen in the past. I also get info from manufacturers

[@marilyngatson2289]

Do you check this with the ac on or everything turned off? How do I know if my compressor isn't working? I am having some freezing over my evaporator coils starting. All vents and coils.are clean.

[@mikmaster63]

Checking the compressor is done with no power going to the AC. I almost always check the amp draw of the compressor to see if it’s working correctly. I also check to see if I have 20 degree drop across the evaporator. Newer AC’s have a freeze sensor. Make sure the freeze sensor is installed and hasn’t fallen out or it hasn’t failed. If it’s an older AC without a freeze sensor I’m not sure what can be done about that. Make sure there aren’t any air leaks.

[@marilyngatson2289]

@@mikmaster63 thanks for the info. Just checking if I turn off the breaker to the AC to check amps for the compressor it will still read right? I ordered another freeze sensor for the AC to see if it stops freezing over. No leaks or air flow. The unit is 6 years old and has been working great but two days ago started freezing up. All coils are cleaned and nothing blocking air flow. The freeze sensor is in place still. I am hoping it just stopped working.

[@mikmaster63]

No, the breaker has to be on to check the amp draw. I think you may need a technician to look at it. The air leaks to look for are at the divider for the duct that separates the in/out air.

[@mikmaster63]

No, the breaker has to be on to check the amp draw. I think you may need a technician to look at it. The air leaks to look for are at the divider for the duct that separates the in/out air.

[@mikmaster63]

Other things to check, make sure the coils of the evaporator and condenser are clean. Vents are open. Ducts aren’t blocked. Coils aren’t damaged. And as mentioned earlier recirculating air leaks. Air leak between the return and discharge air. I haven’t had to replace a freeze sensor on the newer ACs. Low failure rate as far as I know. Checking the amp draw is how I check for low charge on the compressor. If it freezes up within 20 minutes it’s probably low charge although it’s rare. If it’s taking longer it’s probably air leaks. Running the fan on low can cause freeze ups also.

[@bigsleeperstudios8865]

I have a Mach 3 roughneck I tried this diagnosis and I’m not getting any power from the purple and white wires as you had. So could this be a bad switch at the panel? I don’t have a wall panel it’s only controlled at the unit

[@bigsleeperstudios8865]

And so I pulled the switch out to get a better connection and I have 12 volts if I touch my red to the purple on my meter but as soon as I touch the white it goes to 1 and that’s all it shows

[@mikmaster63]

Need more info. I’m not sure what switch you are referring too. The white (neutral) and the purple (hot) are AC voltage. That’s high voltage and should measure around 120 volts AC. The wires at the thermostat that tell the board to turn on the compressor are the yellow (+) and the blue (-). They may be different colors at the board. Is the fan blowing?

[@mikmaster63]

So you don’t have a thermostat??? This video doesn’t cover ceiling assembly with manual controls…

[@bigsleeperstudios8865]

@@mikmaster63 yes the fan is blowing.. maybe I misunderstood some of your video. I’m thinking the switch that turns to fan/heat/ low cool/ high cool but the compressor isn’t coming on at all. It was working fine and I had my vehicle washed and after that it’s not working now. I checked all the wires up top but I don’t see anything broken or loose

[@mikmaster63]

Are there knobs on the ceiling assembly?

[@glennwallace9203]

Would have been helpful to also show how you got access to the control board inside the HVAC?

[@mikmaster63]

Ya, I’m working on making better videos

[@gregp39402]

Why did you not check the board itself? just because the thermostat and the wires are ok to the board doesn't mean its making it through to the unit.

[@mikmaster63]

Looks like 40 seconds into the video I was checking the output of the board??? As I mentioned in the video this is to help RV technicians are just starting out. So it’s an exercise of troubleshooting…