Coleman Mach 8 AC - runs, no cold air

[pconroy328]

2016 Coleman Mach 8 AC unit. No probs until today. Fans are running (squirrel and coil fans are running). Coils are clean, whole unit looks pretty clean under the cover.

I suspect the compressor ain't doing it's thing.
I've got an event to hit tomorrow so it'd be nice to see if there's a jury-rigging I can do.

I've got a good multimeter.
Can someone suggest some troubleshooting tips to see why it's blowing air but not cold air?

thanks!

[pconroy328]

An update. Ordered a cap since it was a $30 fix and a logical starting place. My wife, bless her heart, watched a dozen Youtube videos and had it replaced by the time I got home.

I'm not sure she even knows what a capacitor does. 🙂
There's a YouTube video for everything.

Compressor is running.
We didn't test it for long, I'm a bit concerned that the air wasn't as cold as I recall.

But it was a cool night.
Tomorrow we'll fire it up again and see if we're out of the woods.
Or if a new upper unit is going to be required.

Thank you for all of your help!
Our fingers are crossed it was just the cap!

[DFord]

Did you find any suspect quick connect terminals or wires burned where they connect? Bad capacitors are not known to heal themselves. Does the one in the metal can (the run capacitor) show any signs of bulging? That would be a sure sign it's gone bad. The start capacitor would usually show signs of damage if it were bad. The overheat very quickly if left in the circuit very long.

[pconroy328]

DFord wrote:
If it was the capacitor, the compressor would be hot from trying to run without it.

Thanks. Friday the compressor wasn't running. Yesterday, I musta bumped it enough that when I powered it on, the compressor started up. And it did get warm.

I went ahead and ordered the Start and Fan capacitors off Amazon and will replace them.

My fingers are crossed that's all it'll take.
Thanks for the help!

[dougrainer]

twodownzero wrote:

dougrainer wrote:
If the compressor is running, then your Unit is shot and the upper unit needs replaced. Doug

I haven't seen an A/C compressor that ran in a unit that didn't produce any cold air yet.

Really, You base your comment on what expertise? I am basing my comment on 40 years and still working as a RV Tech. IF the compressor is Running, and NOT producing cold air, the Coolant is gone or the compressor valves are bad. Either way, you replace the upper AC unit. Doug

[DFord]

If the compressor was running and not circulating on refrigerant (not cooling) it would be way to hot to touch after just a few minutes.

[twodownzero]

dougrainer wrote:
If the compressor is running, then your Unit is shot and the upper unit needs replaced. Doug

I haven't seen an A/C compressor that ran in a unit that didn't produce any cold air yet.

[dougrainer]

If the compressor is running, then your Unit is shot and the upper unit needs replaced. Doug

[DFord]

If it was the capacitor, the compressor would be hot from trying to run without it.

[pconroy328]

Thanks - will pop back up there tomorrow! Compressor was NOT hot. Nothing was up there.

Hoping it's just a capacitor.
I'll pull the model number and schematic off the unit tomorrow.

Thanks again!

[DFord]

I think it's time to remove the cover on the roof to see if the compressor is HOT. If it is, it's getting power. If it's not even warm, test for power at the compressor terminals. This is LINE VOLTAGE SO BE CAREFUL! Under the cap on the compressor the wire terminals should be labeled C - S - R. That stands for Common, Start, and Run. You should be able to find 120v between C & R. If not, try measuring voltage between the compressor case or somewhere on the copper tubing and any of the terminals on the compressor when it should be running. If there's nothing there, the compressor contactor may not be pulling in. There will be a coil with smaller wires that you should be able to measure voltage at - probably 24v if the signal from the thermostat is reaching it. Or you could remove the cover from the thermostat and jumper R (red) to Y (yellow) to see if the compressor will start.


You might find some technical information on your AC at this page:
https://www.airxcel.com/coleman-mach/service-support/document-library

Coleman Thermostats Service Manual PDF file:
https://olivertraveltrailers.com/wp-content/uploads/oliver-university/Component_Manuals/AC_Coleman_M...

Not knowing your AC model number, I can't give you a link to the documents there.