True TDD-CT compressor constantly runs but temp wont get below 40 degrees

[HopVillian]

I bought this unit on Craigslist from a resteraunt owner in Va
I ran the serial number on True's website it comes back as a 1994 Model TDD-2CT
It is running R134 refrigerant thankfully..
The unit does have a new compressor, Drier and Capillary tube installed and they look fairly new
I have had the unit running for three days now it never shuts off. The temperature inside the unit is 40 degrees. A poured beer comes out at around 42 first pour and 41-40 the second pour.
I am more concerned about the unit constantly running, then I am my beer temp as my electric bill is going to be huge....
Some questions you might have for me:

(1) Yes I did clean the condensor (GOOD) it had a lot of dust and build up on the fins and the tubes.Unit is completely dust debri free.
(2) Yes the Condenser fan works and does not shut off either.
(3) No matter what number/Temperature I put the thermostat on the unit will not shut off....
(4) If I turn the thermostat all the way down or (off) the unit does shut off
So I think the unit is wired right but it just wont get cold enough to shut it off.
(5) Yes the evaperator fan is spinning and No the Evaperator unit is not Iced up

[djc]

You should worry about the temperature and running constantly because they are related. I'd say you are low on refrigerant. Although maybe with all the new parts there is something going on that the original owner couldn't fix.

[HopVillian]

If my system is low on refrigerant I guess that is a easy fix, assuming it was never charged fully and is not leaking
I do have the high and low pressure valves on the system
when they installed the new compressor and drier/Capillary tube they sweated in the two valves
So my questions are:
(1) Can I buy that R134A for the car in that pressurized can and expect it to work?
(2) what sort of pressures would I be looking at to troubleshoot?

Note: I did notice on my last inspection of the condensor compressor area
It appears that the old Capillary tube was ran with the cold return line in the insulation( I can still see the old one)
The new one that was installed is just bare outside of the insulation...
Will this affect the unit runs /cools? Does the cold return and Capillary Tube need to be together under the insulation?

[KillianBoy]

HopVillian,
A refrigeration expert should be able to tell you about the pressures used on the gauges, but mainly they use weight to measure amount of refrigerant. You could use the one they sell for cars but those are used mainly to get a bad system working for a little while, basically an emergency fix, since you paid for all the new parts, you should tray and get system working like it should.
Normally a refrigeration expert will pull vacuum on the system , once there is a good vacuum, they will add proper amount of refrigerant. They pull vacuum for 2 reasons, make sure they have a good seal, if not seals or connections may be bad and allow air in, and second to make sure there is no air in system. If there is air in system, it won't cool properly.
KB

[HopVillian]

Well I had to put a new Return line coil in 3/8 tubing coil to pull out compressor this got pinched and was causing very low (0 psi low side pressure) and very high ( high side pressure 350 psi)
I borrowed some gauges and a vacumm pump.
So i brazed a new coil in...And then vacummed out all residual dust /debri from soldering with the vacuum pump and checked for leaks..
I then charged with 11 oz of R134A from Walmart 9.99.
Unit is running now and cooling down I will let you know if this was my problem