Forum Discussion

cannesdo's avatar
cannesdo
Explorer
Oct 19, 2016

A/C Problem...Mach 8

It's 2 years old. It will run great then I'll notice it sounds like the wind is blowing through from outside -- at first I thought it was a strong wind coming through from above but there was no wind -- and there's very little air coming out of it when it's on any setting when it does this. If I turn it off for a while then back on it will act normally again. Seems to happen more in the late afternoon after being on most of the day in the heat. Would that be the motor? The fan assembly/legs seem to be in good shape. I already dealt with all those issues and got the new 3 blade assembly and put lock-tight on the leg bolts. Nothing appears to be loose up there.
  • ScottG's avatar
    ScottG
    Nomad
    Oct 19, 2016
    It sounds like the coil is freezing up. You can verify this by removing the filter and looking up at it. There should be a sensor attached to the coil. Perhaps it has fallen off or was not clipped to the fins - mine had that problem.
  • j-d's avatar
    j-d
    Explorer II
    Oct 19, 2016
    Agree with the evaporator-freezing scenario Scott notes. The A/C with wall thermostat have that sensor, but the non-ducted ones (knob controls on the unit itself) do not.

    Especially with non-ducted, it helps to always run the indoor fan on HIGH. With ducted and freeze sensor, my guess would be that it'd still help.
  • sch911's avatar
    sch911
    Explorer
    Oct 19, 2016
    It still should have a freeze sensor even when it's a non ducted unit. It may be a bulb type rather than a thermistor type however. As previously stated make sure it's still clipped in place...
  • dougrainer's avatar
    dougrainer
    Nomad
    Oct 19, 2016
    sch911 wrote:
    It still should have a freeze sensor even when it's a non ducted unit. It may be a bulb type rather than a thermistor type however. As previously stated make sure it's still clipped in place...


    Freeze sensors have nothing to do with Ducted or Non Ducted. It has to do with the CONTROL system. IF you have a wall Tstat, it will have a freeze sensor system. If you have mechanical ceiling mount knobs, then NO freeze sensor. Doug
  • dougrainer's avatar
    dougrainer
    Nomad
    Oct 19, 2016
    cannesdo wrote:
    It's 2 years old. It will run great then I'll notice it sounds like the wind is blowing through from outside -- at first I thought it was a strong wind coming through from above but there was no wind -- and there's very little air coming out of it when it's on any setting when it does this. If I turn it off for a while then back on it will act normally again. Seems to happen more in the late afternoon after being on most of the day in the heat. Would that be the motor? The fan assembly/legs seem to be in good shape. I already dealt with all those issues and got the new 3 blade assembly and put lock-tight on the leg bolts. Nothing appears to be loose up there.


    You do not state which RVP model. But, if you have NO internal condensation drain pump on the RVP and the Drain water drains off the top of the RV, when you have this problem and you either turn it off or just run fan only, you should have a great amount of water flowing out of the unit and off the sides. THAT will point to a freeze up of the evap coil that is causing the noise and the diminished air flow. Doug
  • sch911's avatar
    sch911
    Explorer
    Oct 19, 2016
    dougrainer wrote:
    sch911 wrote:
    It still should have a freeze sensor even when it's a non ducted unit. It may be a bulb type rather than a thermistor type however. As previously stated make sure it's still clipped in place...


    Freeze sensors have nothing to do with Ducted or Non Ducted. It has to do with the CONTROL system. IF you have a wall Tstat, it will have a freeze sensor system. If you have mechanical ceiling mount knobs, then NO freeze sensor. Doug


    That's why I corrected the previous poster who said otherwise....

    Be sure to quote the correct post when criticizing...
  • dougrainer's avatar
    dougrainer
    Nomad
    Oct 19, 2016
    sch911 wrote:
    dougrainer wrote:
    sch911 wrote:
    It still should have a freeze sensor even when it's a non ducted unit. It may be a bulb type rather than a thermistor type however. As previously stated make sure it's still clipped in place...


    Freeze sensors have nothing to do with Ducted or Non Ducted. It has to do with the CONTROL system. IF you have a wall Tstat, it will have a freeze sensor system. If you have mechanical ceiling mount knobs, then NO freeze sensor. Doug


    That's why I corrected the previous poster who said otherwise....

    Be sure to quote the correct post when criticizing...


    You were not totally correct. What you stated was true to a degree. What I stated clarified what you did not. Your "It still should have a freeze sensor even when it's a non ducted unit", statement is not correct. You can have manual controls on both Ducted and non ducted systems and they will not have freeze sensors. Doug
  • j-d's avatar
    j-d
    Explorer II
    Oct 19, 2016
    So we need the OP to tell us which control type his A/C has.

    Doug, thanks for the explanation. Wall t'stat = freeze sensor. Two knobs like an old "window shaker" = no sensor.

    I wonder about the two-year age of this A/C. Could well be time for a good cleaning of the topside unit. Evaporator Core and Drain Pan. If Chris Bryant weighs in on this, I think he'd say an Annual Cleaning is appropriate.

    And! Cleaning provides a chance to see if the Freeze Sensor (given wall t'stat) is in place where it should be.

    What's the correct sensor placement? Can it be tested? How?
  • cannesdo's avatar
    cannesdo
    Explorer
    Nov 25, 2016
    Thanks for the responses. It is a non-ducted A/C. The setting knob (fan/AC settings, low and high for each) and temperature knob (blue to red) are on the ceiling assembly (inside the RV). Water does run off the roof when it's running. I don't know if that happens all the time or just when it's been running for a long time or when it's running normally or sounding whooshy. It still works fairly well most of the time and now it's cooler. Did catch it being whooshy the other day. Seems to happen most during the hottest part of the day.
  • j-d's avatar
    j-d
    Explorer II
    Nov 25, 2016
    Here's a Mach 8 parts diagram



    I'd be good to remove Parts 1 and 2 (possibly 3) and clean everything out. PLEASE DON'T order any parts from this, since it appears to be Aussie and set up for 240VAC!

    Your Mach 8 uses two motors. I'm not familiar with those, but I can say for certain that our Mach 15, with a single motor driving indoor blower and outdoor fan, has never frozen up on HIGH fan speed. It has on LOW.

    I think the "whoosh" noise is being caused by frost, and cleaning, a clean filter, and HIGH speed, will keep it from frosting in use.

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