What could be my problems if my battery was week but when I jump start it on my rv the lights worked but the 120 volt wouldn't

make sure dissconnect is on

I can only reply by asking? 12 volt Amps Amp hours or 120 Volts A/C amperes. Most 5th wheels with a single Air conditioner are rated for 30 amps @120 volts A.C. ( two A/C units will be 50 amps service rating.) As each Air Conditioner takes between 15-20 amps upon starting.
Most 12 volt circuits have variable amps depending on the circuit. If you look at your Fuse panels on the trailer, you have a main breaker for the A.C. 120 volt side...which should be marked at 30 or 50 amps. On the DC 12 volt fuse panel, you can only add up the total of each fuse for the potential of the maximum amperage.
If your question is about Battery-Battery's amp hours, that has to do with how long a specific load maybe placed on the batteries and still perform. Along with the same load and number of minutes before the batteries will go dead. Hope this helps.

Lights are 12V nothing to do with 120 V AC circuit. Check batteries and inverter

I go with the converter solution IF you have controls set properly. I have use a 12V trickle charger (relatively inexpensive) to verify and supplement a weak inverter. Since you said your hook to AC you have power for the trickle charger.

Contact your local service center directly or online here:

Contact Us Family RV Jayco Inc

The lights run off of 12V DC and use your RV's batteries to run when not plugged in. When plugged in it uses the AC and converts it to DC and runs the lights.

Please check your battery disconnect switch. It's most likely off. In my Winne there is a battery disconnect switch which disconnects the two batteries near the door. Lights wont work when unplugged and the switch is off. Lights works when plugged in or unplugged and switched on.

120-
VOLT
AC
SYSTEM
The following electrical components (if so equipped) will only operate when your
RV is connected to shore power: 120 to
12-volt power converter, air conditioner,
120-volt refrigerator, microwave oven, television(s), fireplace and appliances
plugged into convenience receptacles.

SECTION 6 - ELECTRICAL SYSTEM JAYCO TOWABLE
6-2
120-
VOLT
CIRCUIT
BREAKERS
The 120-volt AC circuit breakers located in
side the main load center protect all
120-volt wiring and components in the RV fr
om circuit overloads and short circuits.
Should a circuit overload or short circui
t occur the circuit breaker protecting the
affected circuit will "trip" preventing the flow of electricity through that circuit.
If a circuit breaker trips, shut "off"
the appliance on that circuit (i.e., power
converter etc.) and allow the circuit breaker to cool down for a brief period of time.
After the cooling down period, reset the circuit breaker by moving its lever "off" and
then back to the "on" position. If the circuit breaker re-trips or frequently trips,
contact your dealer to have the electrical problem diagnosed and repaired.
A circuit breaker identification label is permanently attached to the inside surface
of the 120-volt load center.
Maintenance and Replacement
At the beginning of camping season, inspect the circuit breakers and replace as
needed. Test by turning each circuit breaker "off" and back "on". Circuit breakers
are wearable parts and must be replaced
as needed, as part of your RV
maintenance. If you have any questions, consult your dealer.
Please contact your dealer for repair assistance when replacing circuit breakers.
CONVERTER
The power converter converts 120-volt AC power to useable 12-volt DC power
when the shore power cord is connected to an external power source.
The converter has a built-in protective thermal breaker that will shut it down should
overheating occur. Overheating can be
caused by operating the converter above
its maximum power output for an extended period of time, or by an obstruction to
its ventilation air flow. To reduce converter heat build keep unnecessary 12-volt
lights and motors turned "off"
.
Keep the converter cooling fins and fan clear of
obstructions.
Inspection and maintenance
If the 12-volt power converter is not working (auxiliary battery not being charged)
check the reverse polarity fuse(s) in the converter fuse panel.
There are no
customer serviceable parts inside the converter case and the
manufacturer's warranty will be void if
the case has been removed
. If you
have further concerns contact your dealer.

I have no idea what you're asking.
Contact your local service center directly or online here:

A TRANSDUCER WILL STEP 220 DOWN TO 110 .
I BELIEVE AN INVERTER WILL BOOST IT FROM 110 TO 220 A ALL IN ONE TRANSFORMER WILL WORK