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Originally Posted by snowbird225

It is a walgreens.

we service all the walgreens a/c and refrigeration equip. down in miami,fl. i had ancident like yours but not with the cond. fan motor. trane rtu would run fine in the day then they call back in the am its hot again after about the 2nd time i went out early morning i seen the intallation company installs an inline float switch on the drain, then on the drain pan they clip this probe type overflow sensor on the pan i seen it had moisture on it so wiped it with a rag and bam the unit kicked on. i removed it and never called back again. on fan on at night the coil will get colder with the water swirling in the pan it will hit the sensor........


here in south florida a company is changing all the rtu's out for walgreens from carriers to tranes if its a new trane check that out.

Is this a Trane Voyager with the UCP? If yes, have you taken the outdoor air sensor and discharge air sensors and checked their ohm readings? Also have you taken the outdoor sensor loose, pulled the tstat wires from the TB, hook the sensor to terminals one and two (NOT Test 1 & 2) and put the sensor into the return to test the unit for a while to verify operation ( I carry an extra thermistor just for this purpose)? In this mode it will maintain (if I remember correctly) 68F heat and 74F cooling until the cows come home. No intermittent fan, no freeze stat, and no economizer (can get you by if a bad tstat is found until you can get a replacement). Also if a Zone Sensor Module is being used have you done a factory "Reboot" of the Zone sensor module, if one is being used to see it it is having a brain fart? It will also show a "Pass/Fail" of its start-up.

I thought the same thing. We will find out tomorrow. I have feeling I'll be back out there.

Huh .... Odd that it would lock out at night due to high amp draw on cond fan.

fixed

Another tech went out this morning and eventually found that the condensor fan motor was pulling to many amps. He found the compacitor to be bad. I guess we will find out in the am if that was all it was. Thanks for all of the feed back guys.

check superheat and subcool. only pressure not good enough

Heres a guess. There is an occupied switch, relay, out something to that effect that when energized cuts the blower out. This cause low pressure and or freeze stat. Maybe a timer something that breaks "g" or maybe the blower contractor since it it's a a trane unit and don't want to use normal terminal designations
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It is a walgreens.

Shows normal operation on the board. I'll try to disable the economiser. I just don't see why it works all day and not at night. I take that back I did check the board on the economiser and it showed co2 sensor but not the last time. Where would that sensor be at?

check for power at y1/2 in the morning...if its there than check where control voltage is being held up.

are there multiple units for this customer or are you on a plaza roof of some kind?

Are there any codes on the UCP board? I had a trane rtu that never gave me any alarms. The whole time the board was showing normal operation, condensor fan motor was the problem. it was tripping on internal overlaod after a few hours of running, also you may want to disable the economizer.

No just a trane tstat

Is it on any type of control system ?

Could the economiser do this

Yes, I go out in the morning and when I get there it is out on cool fail. So i reset the unit after I look for faults. I was running an 80 psi suction and 255 on the head. (R22) I watched the unit cycle on and off and the tstat seems to be operating great. I pm'ed the other units and kept coming back to check this one and it was running good. suction line sweating and temp in the conditioned space was 72 just as it was calling for it to be.

the unit fails at night and it starts working in the morning by itself, or do you go out and reset at the disconnect?

check t-stat programming, change the battery...

what are the pressures at 95F?

not much to work with here, more info needed.

No the set point is 72. The ambient temp is 85 at night and 95 during the day.

Originally Posted by snowbird225

It is a trane tstat. And the temp at night is about 85 degrees. During the day temp gets to about 95 or so.

Are you saying that the SETPOINT is 85° overnight? What is the overnight ambient temperature?

It is a trane tstat. And the temp at night is about 85 degrees. During the day temp gets to about 95 or so.

How cold does it get at Night Below 55? If the temp drops low over night it could be failing cause its not desgined to work in those conditions unless the proper controls where added.

"Take the batteries out shake them and blow on them. Place them back in and that should do it"