McQuay Condensing unit.

[CHILL IT]

Hello, Checked out a McQuay M-0C2050BH27-ER11 S-STNU051100019 Unit has 4 comp. 2 per circ. My guage psi. was 70 psi with 1 comp on this circ. running. This is circ. 2. Interface read circ. 2stage 1 reQ 2 Interface pressure was 57.8 psi. suction. Manifold pressure like i said was 70. psi. Interface read circ.2 status 1 evap. pressure low. Status 2 Demand limit stage 4. My question is since my interface pressure is reading 57.8 and my actual pressure is 70. Could the suction pressure transducer be defective causing the demand limit and not allowing comp. 4 to run. ?

[ryan1088]

I'm assuming this is a microtech 2 controller? There is an offset you can put in the controller but you have to know how to do it and have the appropriate password. I'd say you are getting a low pressure hold from the controller not allowing it to stage any more. Sounds like you are on the right track. Fwiw, I don't have any experience in demand limit.