AboutCraig HVAC Expert Expertise I have been in the HVAC field for the past 12+ years. I can help with most HVAC questions. I work on commerical buildings for the most part, and have yet to find anything I could not troubleshoot and repair, when repairable. I work on small 1 ton units to a 2500 ton chiller. Troubleshoot air flow, elect, and control problems. I attend regular classes to keep up with the latest and greatest.
Experience I have work in the HVAC trade for the past sixteen years. I work on commerical sites, hospitals, gov't buildings. I can troubleshoot just about anything in the HVAC business.
Education/Credentials 5 years union trade school, VFD training classes, Liebert factory training, some York and Trane factory training.
Question my home HVAC unit (carrier) is having an issue. if I have the A/C unit shutdown for serveral hours both the fan and compressor will start with the command from the thermostat without a problem. once the thermostat achieve the desired temperature it send the shutdown command to the A/C unit. several minutes later when the thermostat send the starting command again, only the Fan will start, and the compressor will start somewhere about 15 minutes later during the hot summer days of houston and 2 minutes later during the summer nights.
If I put a water hose to the compressor motor (Bristol Hermetic model H89B303ABCA of 30,500 BTU) for few minutes until it cool down the compressor case, it will start together with the fan when the thermostat send the starting command, it will tell that the compressor unit is overheating during operation.
I have cleaned the coil several times this week, it couldn't be better cleaned from both inside and outside, there is not damage to the coil cells, they looks as installed in 2005.
The fan spins well and match the current plate when I checked with the AmMeter, around 0.7amp
this type of unit has the overload protection integated inside the compressor case.
I have checked the current of the compressor during operation and it's around 15amps, the A/C plate indicate 16.7amps RLA.
I also check the starting amps when the compressor is hot, it goes all way to 114-amps and won't start until the fan running alone will cooldown the case (15 minutes), or if I accelerate the proccess by watering the compressor case.
the unit has an starting kit and a regular dual run capacitor (GE 370vac/45uf). as far as I can tell they both works well by starting the unit as long as the compressor thermal protection is not actived. but the fan will start all the time regardless the compresssor.
The is not freezing on the lines and not visible leaking around. when the compressor unit finally start it will cool down the house and you won't tell the problem until it try to start again as I explained above.
the Last company who made the inspection on the unit left the Puron pressure at 140 over 320 the last summer 2008, and it has been running perfect until it started with this issue 2 weeks ago.
any help on why my compressor unit is overheating?
Thanks in advance,
J.Sosa
Answer Causes for compressor overheating.
Poor refrigerant charge (slugging or short on charge)
Dirty cond. coil
Non-condensables in the refrigerant.
Weak start cap
Weak run cap
Poor elect. connections
Contactor contacts not making good connections
Low voltage
Weak compressor
If this problem with the compressor continues, it will fail. My guess is that the start cap is weak or bad, and does not give a boast when it is really needed during the heat of the day.
