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Topic: Thomas TA-4101 DC Aux Compressor drawing too many amps (Read 1154 times) previous topic - next topic

Thomas TA-4101 DC Aux Compressor drawing too many amps

My 40 amp circuit breaker to the Aux Compressor is tripping intermittently.
After talking to James T. he said the compressor is probably drawing too many amps and the brushes needed to be replaced.
I got out my new DC amp meter, drained some of the air to kick in the compressor and measured the amps .
It read the normal 28 amps but after a few times it started to go up to 33 amps.
So it could be the brushes.
I have searched for a diagram showing where on the compressor the brushes are to no avail.
Also can't find a part number to order them.
Has anyone done this yet?
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #1 –
Berry,  Why is a 28-33 amp load tripping a 40 amp breaker?
"97 40' U320 build 5035

The best things in life are not things.... It's fulltiming in a Foretravel.

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #2 –
Quote
Barry,  Why is a 28-33 amp load tripping a 40 amp breaker?
It is not, but it was trending higher & I was thinking it is the most likely cause.
Since it is intermittent, it is hard to catch it when it happens.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #3 –
Barry,

Sounds like the breaker to me.  I'd try switching in another one before messing with the compressor.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #4 –
Barry,
First question is, what should the compressor draw in amps ? surely it is marked or James T might provide the correct info.
Doubt it is over 20 amp if working proper.
I wonder if that breaker is a Thermo-Magnetic type or what type is it.
If the current draw runs over 80% for a few minutes before tripping, I would guess it is a Thermo type, getting warm/hot then releasing.  If it trips quickly then it would be the magnetic type.
80% of 40 amp sounds like 32 amp.
Most electrical items are rated at 80%
As usual, there are many exceptions to the above rules.
Lots of questions
AS Usual  FWIW
Dave

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #5 –
Quote
First question is, what should the compressor draw in amps ?
According to the specs it is 28 amps.

 Compressor and motor performance data
Max Cont Pressure: 100 PSI        Motor Voltage: 12V DC                          Motor Type: Permanent magnet
Max restart Pressure: 100 PSI    Current at rated load: 28 A              Full load speed: 1800 RPM
Max Ambient Air Temp: 104 F      Power at Rated Load: 340 W                Horsepower: 1/3
Quote
If the current draw runs over 80% for a few minutes before tripping, I would guess it is a Thermo type, getting warm/hot then releasing.

I have not been able to catch it when it happens.
I have a "baby monitor" in the compartment that I listen to in the house for the compressor to come on.
Then I run out to check it.
I will go buy a new C/B and replace it just to eliminate one more possibility.

Any ideas on where the brushes are located in the compressor.
Since I have seen the amps going up to 33 ,I think it would also trip a new C/B.
It should be staying at 28 amps
Thanks
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #6 –
Barry,

While you are there, verify that wire to the compressor is of sufficient gauge (depends on length of the wire run) to carry that kind of load with low line loss. 

Inadequately sized wire for that 28 amp load could easily throw draw over the breaker's rating.

You can always measure voltage with the compressor running at the compressor and then again at the battery.  If close to the battery, measure from battery positive to compressor positive to determine voltage drop due to wiring/solenoid(s).

Brett Wolfe

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: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #7 –
Quote
You can always measure voltage with the compressor running at the compressor and then again at the battery.  If close to the battery, measure from battery positive to compressor positive to determine voltage drop due to wiring/solenoid(s).
While running the compressor.
At the C/b it reads 13.19vdc & at the pump it is 12.97vdc with 4 to 5' of 8 ga in between the two.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #8 –
Good info,
10ga good for 30 amp
 8 ga good for 40 amp
 6 ga good for 50 amp

the voltage drop for the run and amp draw should be acceptable.
another area to check, connections for dirty - loose - insecure.
FWIW
Dave

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #9 –
Quote
another area to check, connections for dirty - loose - insecure.
Both connections at each end are tight and clean.
One short wire run with no connections in between.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #10 –
Berry,  I think the brushes are under the two flat covers at the far end of the motor, you can pull one of the covers and see what the commutator looks like. maybe clean it up if it is dirty. I am thinking there maybe something on the commutator causing the motor to hard start only when the motor stops with the dirt, brushes and commutator all lined up.... kind of like getting the stars to line up.. :))  that 33 amp reading you are getting could be a dirty commutator, if not I would check to see if there is any restriction in the air intake. something is causing the addition load.

good luck...

Ted
"97 40' U320 build 5035

The best things in life are not things.... It's fulltiming in a Foretravel.

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #11 –
Quote
Barry,  I think the brushes are under the two flat covers at the far end of the motor, you can pull one of the covers and see what the commutator looks like.
Finally got a hold of Thomas Compressor which referred me to a distributor.
They don't have the brushes in stock.
They have an order in since June and it has not arrived.
Thomas Compressor has been bought out by a larger company and is merging 2 locations and the backlog is horrendous.
They don't have a parts breakdown showing where the brushes are.

Part # kits:
C85493-P Minor Service Kits (Includes C85485-P Valve Assembly Kit and C87860-P Ring Service Kit) - replace at 6000 hours continuous duty/maximum pressure (33% duty cycle =2+ years).

Major Repair Kit (Includes C85493-P Minor Kit and Piston Rod Assembly. Kit Part Number on Front) - replace at 12000 hours continuous duty/maximum pressure.   

C85517-P Brush Kit (needs 2) - Replace at 1000 - 2000 hours. $38 X 2 = $76.00
Thomas TA-4101 DC Specifications

Foretravel Parts said they cannot get them either or HWH
Only option is buy a new compressor was there suggestion.
The distributor was willing to sell me a new compressor at 35% off $546.00
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #12 –
Barry,
 
When you replaced the DC compressor, did you get a bigger one or was the old one already larger than in a 2002 U320?  Mine looks so small compared to what the factory installs now. I think a bigger one would be the way to go.
 
Jim
2002 U320
Jim Frerichs
2002 U320 42'

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #13 –
Quote
When you replaced the DC compressor, did you get a bigger one or was the old one already larger than in a 2002 U320?
I already have the larger one.
I was offered a deal for a new one but I did not replace it.
It is a lot of money for only needing a pair of $38 brushes.
I am exploring other options.
Maybe there are other brushes I can find that might work.
I am over my pay grade now.
I will look for a compressor repair company & see if they have any suggestions.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #14 –
Barry,
 
Good plan, please post your findings for the group.
 
Jim
2002 U320
Jim Frerichs
2002 U320 42'

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #15 –
Quote
On 9/7/2010 10:35 PM, Barry Beam wrote: 
Quote

 When you replaced the DC compressor, did you get a bigger one or was the old one already larger than in a 2002 U320?
 
I was offered a deal for a new one but I did not replace it. It is a lot of money for only needing a pair of $38 brushes.
I am exploring other options.
Maybe there are other brushes I can find that might work.
I am over my pay grade now.
I will look for a compressor repair company & see if they have any suggestions.
 
Barry BEAM #16014
Coach Build # 6024
Villa Park CA 2003 U320 40' AGDS
03 Acura MDX
FORETRAVEL Motorhomes service and Repair Information
foretravel motorcade - california chapter
"Whatever the mind can conceive and believe, it can achieve"
 
I've filed down plenty of sets of brushes in my day... As long as you can make them fit in the holder and the pigtails will connect...
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #16 –
I agree with dave.  As long as the replacement is close, it is only carbon, and sandpaper will make an oversized brush fit perfectly, as long as you can hook it up. ::)
Michael Baldacchino
'97 40' U320

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #17 –
Quote
as long as the replacement is close, it is only carbon, and sandpaper will make an oversized brush fit perfectly, as long as you can hook it up
Thats why I thought I would have someone who works on these look at it..
There has to be a way to replace them verses buying a new one.
Thanks
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"
 

Re: Thomas TA-4101 DC Aux Compressor drawing too many amps

Reply #18 –
Barry,

Might be worth taking a photo or brochure by a good auto electrical shop (one that rebuilds starters) since it is the electrical end, not compressor end that needs attention.

Brett Wolfe
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