AC compressor starts with tick sound and ups stops for fraction of second

[Shantanu Bandyopadhyay]

My Hitachi 3 * AC runs normally at 28 degree. No cooling problem. But compressor starts every after 5 minutes. And run 3 minutes. When comp starts then only my computer UPS fails for fraction of second. Causing the computer reboot. APC 600 V UPS. NEW. 4 Sq MM wiring. No voltage fluctuations. Hopeless. Please suggest

 

[velocityg4]

Call an HVAC repairman. Sounds like a problem with your air conditioner.

 

[Snipergod87]

My guess is the sudden huge increase in power draw is causing this, Is the UPS and the compressors on the same circuit?

 

[InvalidError]

The air conditioning compressor running for a few minutes, stopping for a few, rinse and repeat sounds like normal operation: phase-change cooling is all-or-nothing, the compressor turns on until room temperature gets below set point, then stops until it crosses the hot threshold and turns on again. Since the compressor motor is initially in a stalled condition, it draws a substantial inrush spike and you get a momentary AC voltage dip.

If your computer shuts down when the compressor kicks in, it may be because your UPS' transfer time is too slow for your PSU, your PSU has poor compatibility with the UPS' output waveform, the UPS' battery is in sub-par shape, the UPS is under-sized for the load you are putting on it or the UPS is defective.

As velocity wrote, it is also possible that your AC is drawing excessive current but your UPS should be able to take over if the voltage sag is that bad, so this can be treated as a separate issue.

 

[SgtScream]

Plug the UPS or the AIR conditioner into another outlet or circuit. Test by using an extension cord to plug into an outlet on a different circuit.

 

[TJ Hooker]

If this is highly reproducible I'd be tempted to see if the PC still restarts if it's powered without the UPS. The UPS clearly isn't doing its job anyway, maybe the UPS itself is causing/worsening the issue.

 

[k1114]

It's not normal to run for 3 mins and every 5 min. Many ac units have a delay to protect it from short cycling the compressor. If you think it's normal and just getting to setpoint, turn the temp down and you'd see if it is the issue. I don't think that's it. I think it has some issue where it's turning itself off but is still being called on so turns back on after the delay.

 

[InvalidError]

If you think it's normal and just getting to setpoint, turn the temp down and you'd see if it is the issue. I don't think that's it. I think it has some issue where it's turning itself off but is still being called on so turns back on after the delay.

Every room AC, fridge and HVAC heat pump that I have ever used operates using on-off temperature regulation... the compressor either runs or doesn't since it needs to achieve phase change on the hot side and that only happens while the compressor is operating close to its nominal flow and pressure range.

My room AC is the same: runs the compressor continuously until it reaches my set-point temperature, then cycles on-off as needed to keep it there. I haven't timed how long a typical cycle is, but it is short enough to be somewhat annoying. Since I'm mainly running it to dehumidify, I often end up setting it colder than I want to stop the cycling, then turn it off altogether when I don't want the distraction for a while or before going to bed.

 

[k1114]

And it takes a min to get to those pressures so running for a min while in that range will do almost nothing. Maybe the cheaps one don't have a proper deadband but either way it's bad for the compressor to turn right back on after it just turned off if it had no delay and it's inefficient from running for a short time.

 

[InvalidError]

And it takes a min to get to those pressures so running for a min while in that range will do almost nothing.

Based on the pitch, my window AC takes 5-10 seconds for its compressor to reach steady state. After that though, it does take a while to cool down the evaporator enough to produce meaningful cooling, especially when the starting room temperature is something like 35C.

The dead-time between restarts is mainly for letting the condenser get down to ambient temperature and pressure equalize so the compressor doesn't start against excess residual working pressure which could cause it to stall and burn out or trip breakers.

 

[k1114]

You're explaining everything I'm saying without me having to explain how ac works. That stuff complicates customers so I have a habit of not going into it. With the op mia, we won't know what the issue is.

 

[InvalidError]

You're explaining everything I'm saying without me having to explain how ac works.

The Carnot cycle (give or take a few tweaks for efficiency's sake in cooling/heating applications) isn't rocket science.

 

[k1114]

And you know what kind of people we deal with when they plug a power strip into itself and think it'll have power.

 

[denniseversole]

An air conditioner is a very good option for cooling the air and make us feel pleasant from the hot atmosphere which is present outside the room. Due to heavy load power and excessive use of air conditioner the compressor of the air conditioner can burst or may burn. So for that, we have to set a proper limit of using the air conditioner.
Air conditioning repair Santa Barbara helps you dealing with this problem by giving its best service on time.