Coleman-Mach AC Blower Problem- Help!

[JoshTab17]

Hello! I just bought a brand new Coleman Mach ac unit for my fifth wheel which previously had a Carrier Air V in it. I used the Carrier to Coleman conversion kit because I am keeping the carrier faceplate because it has a built in thermostat and controls my furnace as well, all via remote. Well, everything has been working fine for about 9 months...until last week.

When my air conditioner kicks on, you can hear a click meaning that the AC is kicking on in auto mode but the blower fan will not turn on. (Typically, the fan will start blowing and then about a minute later the compressor kicks on.) Not sure what the problem is. All maintenance has been done and its not the wiring because it has been working just fine for just 3 months short of a year. Now, even in low mode (continuous fan with AC) the fan will shut off by itself and the compressor will still be running, though the fan should run until I turn the unit off.

THinking maybe my control board might be bad. Any ideas? Thanks!

[Bluepill]

1. Find a wiring diagram either online or inside the A/C unit.

2. See if there is one wire for fan control and another for compressor running between the thermostat and the A/C. If so, monitor the voltage on the fan control line to see if it is the thermostat that is failing to supply the control signal.

Note: if you have a digital thermostat, it probably only sends data signals and you would have to monitor the relay control inputs at the control board.

Searching online sometimes finds the factory service manual that gives step-by-step troubleshooting. info.

[email]

If the compressor kicks on, and the fan runs in low mode, that rules out the tstat and (most of) the control board.


Without knowing what tstat you have, you can try to run the fan only on high and low. If it doesn't run on high, but it runs on low, that sounds like a capacitor issue.



DO NOT mess around with the capacitors without doing some research. If the caps are working fine and are fully charged, just touching the contacts will hurt you.