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Topic: Time to replace an air conditioner (Read 896 times) previous topic - next topic

Time to replace an air conditioner

On my daughters Foretravel Nimbus, we have a Dometic Penguin HP Heat Pump 15k 15,000 BTU Air Conditioner going bad. Sounds like the motor is seizing up at times because the motor sounds like it jammed up and amps on the guage starts running well over 30amps. I first thought we were having a brown out but the progressive unit did not shut down or threw a code indicating poor incoming voltage. When I shut if off and wait before restarting, it will run fine again.

If I am to replace this unit, what would be the best unit to replace it with? Would a new unit fit over the existing hole without a major retrofit? What about the wiring if I need to change the five button thermo to the more modern thermo. These are the questions I am asking myself and turn to you in the forum for some assistance. Maybe, I should try to replace just the motor if possible.

Any suggestions would be greatly appreciated. I will need to do the repair in Florida since the shop is now booked until April of next year.

Thanks!
Bob & Kathy
2007 Nimbus
Full Timers
Retired Charter Bus Owner/Operator

Re: Time to replace an air conditioner

Reply #1 –
If you are talking about the fan motor (not compressor) they are a lot less expensive than a new unit.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Time to replace an air conditioner

Reply #2 –
Quote from: wolfe10 –
If you are talking about the fan motor (not compressor) they are a lot less expensive than a new unit.

Thank you for your thoughts. How do I know the difference? I hear the fans running below and when it jams up, it sounds like the fans stop running from inside the coach. Your help is greatly appreciated I know you are the person to go for advice.
Bob & Kathy
2007 Nimbus
Full Timers
Retired Charter Bus Owner/Operator

Re: Time to replace an air conditioner

Reply #3 –
Turn the A/C control to FAN only (at least I have that option on mine).  It it makes the noise then, it is the fan motor, as the compressor will not come on.

Could be something as simple as a loose set screw on one of the squirrel cages, mud dubbers nest on a blade causing an unbalance, etc.  Certainly worth a look.

You could also go up on the roof, remove the cover and have someone start the A/C and visually see and hear what is going on.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Time to replace an air conditioner

Reply #4 –
Quote from: wolfe10 –
Turn the A/C control to FAN only (at least I have that option on mine).  It it makes the noise then, it is the fan motor, as the compressor will not come on.

Could be something as simple as a loose set screw on one of the squirrel cages, mud dubbers nest on a blade causing an unbalance, etc.  Certainly worth a look.

You could also go up on the roof, remove the cover and have someone start the A/C and visually see and hear what is going on.

Bret, I do hear the difference between the fan and the compressor. The compressor has a more deeper tone. I believe that is the one, the deeper tone, that binds up. When I shut the unit down, I do here the unit release its pressure. Then I turn it back on, the fan comes on and in three minutes the compressor kicks in. Do you think there are parts still for these units? Thanks
Bob & Kathy
2007 Nimbus
Full Timers
Retired Charter Bus Owner/Operator

Re: Time to replace an air conditioner

Reply #5 –
Could be a bad compressor, or could be a bad capacitor making it REALLY hard for the compressor to start.

Strongly suggest diagnosing the problem, not just replacing it unless that is what troubleshooting determines.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Time to replace an air conditioner

Reply #6 –
The start and run capacitors for these units are standard a/c capacitors.  If you have a meter that reads capacitance (most of them do not) then check them yourself.  If not then an a/c tech can check them for you.  They are located under behind a sheet metal cover when you pull the plastic cover off the unit. 

In the absence of an a/c tech you could try swapping the capacitors with another a/c on the coach and see if it fixes the problem :)
If you do that, be sure to take pictures before you remove them on both.  Turn off the circuit breakers to them and when you disconnect the wiring on each capacitor short the terminals with a screw driver to discharge the cap so you don't get shocked.

I have replaced capacitors on mine and extended the life several years in the past.
Steven M
98 U270 WTFE 36'
Houston, TX

Re: Time to replace an air conditioner

Reply #7 –
One thing that happens over time is a build up of lint on the shaft bearing/shaft and this slowing increases over time and draws itself into the shaft sleeve bearing resulting in a strangle hold on the shaft.  Take the cover off to expose the squirrel cage and turn it by hand to see if it is seized or not.  A little oil on it will loosen it up for a while, but if that is the problem, you' have to clean out the lint.  I have one that I'm going thru that cycle with at this time.  I have an old Coleman that is seizing up and I can't get to the motor from the bottom, so I will need to get to it from the top.  Haven't been up there to check it out so don't know if I can access it or not.  I was able to loosen it some by spraying a silicon lube from the bottom, but it is not very effective.  Have a great day  ----  Fritz
Fritz & Kathy Johnson
1991 36'

Re: Time to replace an air conditioner

Reply #8 –
I use silicone all of the time for many things but I  have found that it does not work well to loosen up motor shafts. Light oil like 3 in 1 works much better.  It will soak in to any lint or dust and provide lubrication much more effective tan silicone spray.  You might also try cable lubricant like "Dri Slide" from Amazon. It contains an ultralight oil as a carrier for its graphite lubricant and will last even longer than oil.
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: Time to replace an air conditioner

Reply #9 –
Actually, 3-1 increases in viscosity fairly quickly and is NOT the best.

Use any light, non detergent oil such as sewing machine oil.  MUCH better.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Time to replace an air conditioner

Reply #10 –
...or go to a hardware store and buy a "Zoom Spout Oiler" which is turbine oil, and the best for any HVAC motor whether it's on a fan or a pump ...but don't push the long spout back down into the bottle all the way or you'll never get it out again ...don't ask how I know :)
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Time to replace an air conditioner

Reply #11 –
I need to spray it up hill from the bottom, will any of these do that ??  Thanks and have a great day  ----  Fritz
Fritz & Kathy Johnson
1991 36'

Re: Time to replace an air conditioner

Reply #12 –
The Zoom Spout Oiler will squirt oil up its long skinny telescoping spout if you squeeze the plastic bottle. The spout is designed to fit into very tight spaces but only deliver oil one drop at a time. You don't want to over oil HVAC motors and you don't want to get oil anywhere other than inside the bushing / bearing. An aerosol spray can will probably be very difficult to control.
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)

Re: Time to replace an air conditioner

Reply #13 –
Scott  ----  Thanks, I'll give that "zoom spout oiler  a try  ----  Have a great day  ----  Fritz
Fritz & Kathy Johnson
1991 36'

Re: Time to replace an air conditioner

Reply #14 –
It's by far the best oil for HVAC motors. Every homeowner should have one handy. One of those little bottles will last you a lifetime... if you don't accidentally push the telescoping spout down inside the bottle that is... Doh!
Scott Cook
1991 U300 36' 6V92TA
Old Town Penobscot 16
1984 Honda VF1100C (V65 Magna)