True Freezer- The 5 amp circuit breaker trips when the light on

Question edited for clarity and better English.

Low on Refrigerant Gas. You need a refrigeration engineer.

compressor pump burnt out

kevinmdoyle... Hello and welcome to FIXYA,

Yours is a UK model... so I (usa) can't help you
on SPARES (motor start capacitor) ... however

Circuit breakers do go bad...!!
(easiest & cheapest to check first)

MUCH Easier to test the idea than you would imagine:
- Shut OFF your main breaker.
- Open your panel & swap the wire with an EQUAL breaker
- Tag the wires (to restore when finished trouble shooting)
- Restore the main breaker (wait & see)...

and don't forget to clean that CONDENSOR
per owner manual instructions.

If the failure persists... RESORE the BREAKERS.
and
HOPE it is the START CAPACITOR on your compressor.

Carnac the Magnificent

As soon as you open the freezer door the temp control is at the upper right of the freezer.

You have a dead short.

Are you talking about the fan inside the freezer? If yes, check the following items. The door has a switch that turns the lights off when the door closes, it also turns the fan off when you open the door. If it isn't working right the fan won't come on. There is also a round temperature senser on the coil inside the freezer called a "clickson" that keeps the fan from coming on until the coils are below 20 degrees, it may be bad. If you are low on freon, your coils may not be getting cold enough to trip the clickson. Feel of the small copper line going from the compressor to the coils on the outside of the freezer. It should be almost hot enough to burn your skin if you have enough freon. One other thing to check is the defrost timer. It is a box about 4 inches wide and 8 inches tall with a door on the front of it. Check the connections inside to be sure you are getting power through to the fan. Let me know how it turns out.

get a screw driver and loose the light holder and replace it a new one bought .

http://www.truemfg.com/pdf/InstallManuals/GDM/gdm_english.pdf
This should take you to the site for the owners manual. You may be looking for a technical manual inwhich True doesn't do that. I will be more than happy to answer any questions should this manual not have what you're looking for.
Good Luck.

underneath the unit in the metal box there is a ballast for the lights check it to see if it is getting power and or producing power to the bulbs

If the door seal does not seal completely, replace it. This is very important for freezers.
Contact Rick at Restaurant Parts and More.
\1-888-814-1110. He can most likely get what you need. Just have model and serial numbers and he'll do the rest.
Home Depot and Lowes is a definite no.