Ac compressor won't kick off

[sherpaxc]

Not sure on the exact model. I'm sitting in traffic trying to figure out why is going on with my ac. I have an 08 jayco jayflight with ducted ac. It just has the two knobs that let me set the temp and the other knob lets me put it on low cool, high cool, low fan, and high fan. Anyway, it blows very cold but if I try and adjust the knob so it's not blowing cold air the whole time the compressor won't kick off. It just runs until it freezes up. It takes about 3 hours for it to freeze up. Any ideas what I can do? I've never experienced a compressor that won't kick off.

[Chris_Bryant]

It is the thermostat- that is the only component that would do that- the OP has a purely mechanical setup- no relays, no electronics, just a mechanical thermostat and switch.

[RVnRobin]

sherpaxc wrote:
So what would I need to do to fix this? Do I need a whole new ceiling assembly? I'm assuming the ac on top is working just fine. This is a ducted ac.

If it is the control relay, it is located inside the lower portion of the unit. Remove the inside cover, inside a metal box, circuit board is in there. Should be marked. Last one I bought was about $45 from PPL. Easy fix.

[Jim-Linda]

sherpaxc wrote:
Ok, thanks all. I'm pressure sure it is the thermostat. At least, that is what my gut tells me. I ordered one up and will let you all know if this solves the problem.

Is your gut a qualified technician? This sounds like a good plan to toss money at a problem with litle hope of success.

Jim

[sherpaxc]

Ok, thanks all. I'm pressure sure it is the thermostat. At least, that is what my gut tells me. I ordered one up and will let you all know if this solves the problem.

[Tom_Dee]

Diagnose things first. What does the ice look like? If it is white and frosty looking it is an airflow problem. If it is a hard clear ice then it is either a drain problem or possibly low refrigerant charge. However, yours is a bit different so I would suggest that you shut your A/C off, turn off the breaker, and try disconnecting the thermostat (temperature control knob). Make sure the wire(s) are not touching anything and turn the breaker back on. Does the A/C run? If not then the thermostat is the problem, but if it does run then you need to find a relay or contactor that is stuck shut. This it where the wiring diagram comes in handy.
Tom

[Jim-Linda]

Are you running fan speed on low? That can cause freeze up at times. The "AC" on top is where the goodies are, the ceiling assembly you mentioned contains the control box, connections from the T/S and "top" unit. Try it with fan on high before you panic.

Jim

[sherpaxc]

So what would I need to do to fix this? Do I need a whole new ceiling assembly? I'm assuming the ac on top is working just fine. This is a ducted ac.

[RVnRobin]

Larryect wrote:
Could be a stuck (welded shut) control relay inside the ac unit controlling the compressor.

Had this happen twice while living in an area with "dirty" voltage. Would regularly swing from 90-120v. The lower voltage results in higher amperage with the same load and welds the relays.

[Larryect]

Could be a stuck (welded shut) control relay inside the ac unit controlling the compressor.

[sherpaxc]

Thanks. Now I just have to figure out how to change it. I don't have a wall mounted tstat for the ac.

[Golden_HVAC]

Hi,

You have plenty of freon, or it would not be freezing up.

You have a bad thermostat. It should be shutting off around 65F.

Fred.

[Bobbo]

Sounds like it is low on Freon, or whatever they use in them today.