carrier wont cool down

[roadwarrior]

i have been reading this forum for a while but never needed to post , finally need help.
i have a carrier phoenix ultra reefer , 53 foot trailer. it wont cool down when set at 34 on a hot day it hangs around 40. put in the shop , they said it had a seal leak , they fixed it and recharged . it was originally low by 11lbs. now it goes dowm to 26 when set at 0. i need 0 . it kept running for a while then the fault light came on , it said "alarm cdt " no codes. it shut off and restarted by itself. that is weird , i have been pulling reefers for 15 years , never had that. i think it might be some sensor , but i have no clue , the shop needs the trailer for whole day , iam looking for ideas.

so basically what does alarm cdt mean , and why is it not cooling down faster.

any help appreciated.
thanks.

[DaButcher]

CDT is compressor discharge temperature, the alarm should have been "high CDT"

This unit will usually make three attempts to crank and run before staying shut down.

The R22 Ultra is infamous for hanging around 40f on hot days. Can be multiple causes, in your case it may be related to the high CDT because of the inefficient compressor with high suction pressure. Compressor replacement or repair is most likely what will be done first.

[jagdpnzr]

Need more info. Is the compressor loading up? what's the suction pressure at around 30 degree box temp.

[carrier_trained]

check the quench valve operation
check suction pressure transducer, calibrate or replace
perform comp pumpdown and test
check SV3&4 for leak to lowside(leaks will normally cause poor performance, not high cdt)