Trane TCD Cond Fan Fuses Blowing

[Ansonf]

Since it's happening to all of them, the main thing they have in common is the power source. I those are all good ideas. You could check the electrical room in the building, the breaker for the panel for the hvac? loose main line contact, difference of how much from there to your units?

[rgd2005]

Agreed.I am looking at voltage/power recording options now

[RuralSpaceman]

Found same kinda pblm on McQuay RTU onetime. Eventually learned it only happned during or after rainy weather. Control section was under neg pressure from supply fan and cabinet panels let water draw in and trickle down inside sufficiently to short terminal block on back wall. Of course on a dry day, could not see reason for blown fuses. Made up sheetmetal stand-off for terminal block and later made better panel seals.

[rgd2005]

Thats good to know,thanks for sharing.
btw Welcome to the forums

[Brokanic]

i just had the same problem
installed phase monitor- alarm on under/over voltage almost everyday.
i thought that was causing the fuse to blow almost every two days but i finally spent time on tracing all the wires and found that one wire was rubbing to a point were the intermittent blowing fuse was happening. replaced wire and now the a/c been running fine.

[marvin]

I had that problem before. Almost every week the fuse blow.
Check temp on the fuses using infared thermometer, line side and load side if there is difference in temp change the fuse holder.

i had one almost identical a week or so ago. changed fuse holders &
problem solved. good indicator is the color on each end of fuse.

[Ansonf]

I f you think about it a blown fuse is usually always motor , or wire short.

[marvin]

in some cases yes, but loose fuse holders can cause the fuse to get hot enough to melt the link.especially if the powder in the fuse
has settled from being in the same position for years on the
old fuses & you will notice the end of the fuse getting a
purplish color instesd of normal color.

[rgd2005]

I paid a return visit to this rtu this week and checked the
voltage,amps and for any bad wiring.The fuses were still good.
I just checked it out because the customer thought he was having
another problem.
What I did find this time was an unusual amount of heat in the fuse block area.In excess of 170F in some spots using my
infrared thermometer.
I removed the fuses and squeezed the holders tighter and replaced the sta-con female spade connectors for some horseshoe connectors and tightened these down under the fuse block screws.
Restarted the unit and the highest temperature was 90F.

[JWB]

Nice. Loose connections are the devil. Glad you found something.