mcquay wshp problem

[mrushing]

hey im a tech with about 3 years experience. this is the first wshp i have worked on and im having problems. its a mcquay model#fcu060blfr serial#79f1022504. the problem is the unit will run for only 30 seconds then shuts down. i checked all the obvious things high pressure switch,low pressure switch. i called tech support and they said the diagnostic on the board meant it was low temp switch. the manual isnt with the unit so i didnt know code for diagnostic. so i bypass low temp and same thing. does anybody have experience with this system? i really appreciate the help as i have to have this unit running in the morning its a commercial customer. by the way the yellow led diagnostic is rapidly blinking if thats any help. thanks

[chillerout1]

dont hold me to it but on some of the mcquays swtch was NO and closed on fall so if you jumped it it would still see low temp .try opening swtch and see what happens. it has been a long time since i worked on a mcquay dont really remember but for some reason that sticks in my head.

[mrushing]

thanks i appriciate the help

[manny238]

What are your pressures when the unit does run for 30 secs? That should be enough time to see what your unit is doing. Does your supply condenser line have a strainer? Your either going off on Low or high pressure. I know Mammoth wshp have a condensate over flow sensor. That would be one thing to check.

[nuclear rabbit]

Low temp fault should mean a thetrmistor is strapped to a pipe somewhere, probably water, and its telling the unit it's getting too cold. Do you see 2 purple wires going from the board to a thermistor somewhere???

[ewwilt]

A carrier wshp that I worked on a couple weeks ago had a refrigerant temp sensor in series with the low pressure switch. It was mounted on the liquid line between the accurator and condenser/water coil. It was locking out on freeze protection in heating mode. It was running about 60# suction (r-22) which is about 34 degrees. The ref temp sensor opened at 35 deg. This unit was slightly undercharged. I hope this helps.

ewwilt