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jstaffon's avatar
jstaffon
Explorer
Jul 25, 2017

Don't understand my air conditioner

I have a 2016 Forest River Rockwood 5th wheel with a Coleman Mach air conditioner in the kitchen/living area. I've seen intermittent operation that concerns me. The other day we returned from dry camping/boondocking. It was about 90 degrees outside and sunny. When we returned home, we parked the RV in the driveway and hooked it up to 110 vac, 15 amp service using the 50 amp cable and a couple pig tails to get it to the right connector to plug in the outlet. We then turned on the air conditioner to cool things down while we unload and clean the RV. Everything seemed to work fine. We left the air on all night so that as it heated up the next day it would keep the temp around 70. I went out and noticed it was hot out but the RV wasn't cooling. It sounded like it was running but sounded different. The internal temp was around 88 degrees and the outside temp was 92. I turned the air conditioner off and opened windows and ceiling vents to try and get air flow through the camper. We live in a dry climate and air movement and shade really cools things down. Later in the day, I tested the air conditioner and it seems to blow cool air again. The outside temp was 85 degrees and the inside temp eventually reached temps below 70. I've had this happen before. I took it into Camping World to have it checked. They said everything was fine. They told me they look for a temperature differential of about 20 degrees to know if it's working. I can't seem to get it to fail while the mechanic is checking it. Any thoughts on the unusual behavior?
Seeking Advice
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jul 26, 2017
    One of the thigns you said is you had it plugged into 15 amps.. The breaker for that unit is 20 amps.. now it SHOULD run on 15, but JUST the A/C. I mean even the converter (if batteries are low) may be more than 15 amps can handle.

    And even if you don't trip the breaker,, the voltage drop in the wires may be enough to shut down some things.. LIKE the converter.. If it does not charge the batteries then, unliess your A/C has "local" (Ceiling) controls as my Coleman does (more on that in a second) you loose control power so the compressor won;t start.

    IF you do have Ceiling controls.. Well there is no "Freeze Up" Sensor (Frost sensor) so it can ice up on you (mine did)

    Low voltage also can cause the compressor to NOT START

    My first suggestion is to plug in a good volt meter, Several units exist I will describe them

    MFJ makes a nice backlit analog meter (MFJenterprises dot com as I recall) it has a pass through outlet so you don't even loose a plug.. Expanded range nice meter mine was free.

    I also have an expanded range plug in analog meter of the kind Camping world and other RV stores sell. Much bigger than teh MFJ. but no backlight.

    I have a Kill-a-watt and it has a "Volts" mode (Digital)

    CW and other RV outlets sell a digital with polarity led's. it is a combination volt meter and 3-light outlet tester.

    Plug any of those in and if the voltage is droppign below 110 be worried. 106 is the code minimum and 107 the DANGER ZONE, but 110 and below is concerned.
  • 2012Coleman's avatar
    2012Coleman
    Explorer II
    Jul 26, 2017
    jstaffon wrote:
    Thanks all for your replies! My plans are to install a 20 or 30 amp service for my RV. Having AC while in the driveway is nice when working during hot weather. I also think I'm having icing issues. Does anyone know if you can tie a low voltage or low power condition to icing? Thanks.
    I was asking the same questions recently. Here is something that really helped. I gave this document to my electrician and it confirmed what he was thinking.

    delwhjr wrote:
    Get this document:

    30 amp wiring

    It is a pdf. Print it and give it to him.


    Having this plug means you can run the air and test all the systems at once while sitting in the driveway without worrying about overloading circuits.
  • dave17352's avatar
    dave17352
    Explorer
    Jul 26, 2017
    If you are in a dry climate i doubt you are icing up. I think it is the 15 amp breaker. JMHO
  • jstaffon's avatar
    jstaffon
    Explorer
    Jul 26, 2017
    Thanks all for your replies! My plans are to install a 20 or 30 amp service for my RV. Having AC while in the driveway is nice when working during hot weather. I also think I'm having icing issues. Does anyone know if you can tie a low voltage or low power condition to icing? Thanks.
  • jstaffon's avatar
    jstaffon
    Explorer
    Jul 26, 2017
    2012Coleman wrote:
    OP wrote:
    When we returned home, we parked the RV in the driveway and hooked it up to 110 vac, 15 amp service using the 50 amp cable and a couple pig tails to get it to the right connector to plug in the outlet.
    Maybe I'm misinformed, but I thought that you could not run the AC on household current. I'm not an expert in electricity, but I'm guessing CW plugged into a 30 amp plug. I just had one wired for me at the new house. It's nice having a cool TT to load/unload/do repairs on.


    I hear what you're saying. I'm not sure either. I assumed if the pigtails were not hot or warm while running the air conditioner, everything was ok. I do know that if I run a vacuum cleaner or microwave in the camper while on air con, I'll blow the breaker in my house when connected to 15 amp service. If I just run the air con, it seems to be ok but I don't understand how compressors work and if a low voltage or power can cause problems.
  • jstaffon's avatar
    jstaffon
    Explorer
    Jul 26, 2017
    dkreuzen wrote:
    It sounds like the fan was running and blowing ambient air. I have Coleman Mach 15's on my coach and more than once I have has the same thing happen. It seems to happen when very hot outside (110+), dry, and the coach is hot inside (90+). I have full air flow out the vents so it is not icing up. If I turn off the unit for a minute then back on it will works fine. I think the compressor is overheating and shuts off. It won't come back on without shutting it off and back on. I also notice that if I do not allow the inside temp to get above 85 of so it will stay running even at 115 outside.
    In your case the 15amp extension cord could be overloaded causing a low voltage issue too.


    My experience is similar to yours. It could be related to the pigtails but they don't feel hot when running the air conditioner. Last year, I ran an extension cord to my camper and that ran hot. I don't recall the gauge of wire but I assumed I had a voltage drop that was causing me issues.
  • jstaffon's avatar
    jstaffon
    Explorer
    Jul 26, 2017
    ScottG wrote:
    I'd also guess that it froze up. You could start by making sure the filter is clean. Also, make sure the fan is on "High".


    Thanks for all the replies. I'll try to respond to a few posts with this one. I always run the fan on "High" and the humidity in south east Idaho is very low. Typically around 20 percent. I'm thinking it's an ice up condition as mentioned because it works fine after turning it off for a few minutes.

    I'll continue to read other posts and respond accordingly. Thanks!
  • jplante4's avatar
    jplante4
    Explorer II
    Jul 25, 2017
    Plus you have all the resistance loses of an extension cord. I have a desk full of melted 30a/15a adapters brought in by people who tried to run roof A/Cs of 15 amp circuits.
  • ScottG's avatar
    ScottG
    Nomad
    Jul 25, 2017
    2012Coleman wrote:
    OP wrote:
    When we returned home, we parked the RV in the driveway and hooked it up to 110 vac, 15 amp service using the 50 amp cable and a couple pig tails to get it to the right connector to plug in the outlet.
    Maybe I'm misinformed, but I thought that you could not run the AC on household current. I'm not an expert in electricity, but I'm guessing CW plugged into a 30 amp plug. I just had one wired for me at the new house. It's nice having a cool TT to load/unload/do repairs on.


    You may or may not be able to run it off a common outlet. As Collie Hauler indicated, if the plug is HOT then the connection isn't good enough. It will likely be slightly warm but the warmer it is, the poorer the supply of power is to the AC. It doesn't really matter if CW was able to do it or not. The conditions may be diffferent anyplace you plug in.
    You should really be using a volt meter inside the rig to check for low voltage while the AC is running. Anything under about 106VAC is deadly to your AC (even if the plug is cool).
  • PawPaw_n_Gram's avatar
    PawPaw_n_Gram
    Explorer
    Jul 25, 2017
    2012Coleman wrote:
    OP wrote:
    When we returned home, we parked the RV in the driveway and hooked it up to 110 vac, 15 amp service using the 50 amp cable and a couple pig tails to get it to the right connector to plug in the outlet.
    Maybe I'm misinformed, but I thought that you could not run the AC on household current. I'm not an expert in electricity, but I'm guessing CW plugged into a 30 amp plug. I just had one wired for me at the new house. It's nice having a cool TT to load/unload/do repairs on.


    The A/C will run just fine on household current.

    However, a 15amp household circuit is pushing the limits. It needs to be a dedicated GFCI outlet with nothing else on the circuit. Most RV A/C's pull 13.5 to 14.5 amps to start the compressor. Whenever the RV is plugged in, you lost 0.5 to 1.5 amps of available power to things like the converter/battery charger. One should turn off the fridge and all the breakers in the rig except the A/C if you want to run the A/C on a 15 amp household circuit.

    A household 15amp circuit in the garage or outside can be overloaded if a RV is plugged in and another electrical device is used on the same circuit.

    I would only plug my RV into a 20amp single outlet circuit I had in my garage back when we had a house.

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