Cab air-con was blowing warm air. Unableto reset. ~~~~~ 3667 cab A/c liquid pipe with oil stain.    Retightened liquid pipe coupling. Charged freon to LP = 70 psi HP = 250 psi. Monitor LP/HP pressure for 1/2 hr & pressure able to sustain. Cab A/c coolness - OK. Washed condenser filter & replaced liquid pipe insulation.  Ridzuan/Kamal/Ridzuwan. 02/04/2021.