Fujitsu mini split outside unit gets to hot

[dtherrien]

Its been a while since ive been on here.
Im in the process of installing two Fujitsu 18k minis. Single zone.
One is in place and set up. It will not cool. I did notice today when trying to trouble shoot that the inside of the outside compressor unit seems like it gets very hot. And took a very long time to cool down.
All wiring looks to be correct and seems to be straight forward.
Last weekend i ran it for about 20 minutes and when i noticed it wasnt cooling i shut it off until this weekend.
I let it run for about an hour...seemed to cool a little.
But then i noticed the outside unit was off and hot.
So i shut it off again. Looked at the wiring. It looks correct.
3 wires that connect the outside and inside units with a ground.
2 feed wires from the disconnect with a ground.
The only thing that im not sure if it would effect anything is the install kit come with a surge protector. Which i wired in the breaker panel to the breaker for the mini.

 

[WorthFlorida]

Did you do the install? Is the condenser fan running? The compressor motor probably has a thermo switch should it get too hot it opens the power to prevent it from burning. Are both service valves at the compressor wide opened? Did you try it with the surge protector removed? Did you measure the voltages?

For those who do not know how to install an unit.
AC systems come pre-charged from the factory. After the lines are brazed (may have threaded fittings on mini split) and vacuumed, two valves are opened, one each on the liquid line and the return line at the compressor. This dumps the refrigerant from the compressor to the rest of the closed system. You turn on the system and use a gauge set to check the pressures. If the lines are too long to the evaporator the stored refrigerant in the compressor unit may not have been enough for proper pressure. Additional refrigerant would be needed but if you're low on refrigerant the compressor should not overheat.

 

[Sponsor]

 

[dtherrien]

Yes...I did the install. So in saying that, I am a licensed general contractor.
In hindsite i should have had my hvac person come out and complete the install. But i am familiar with mini splits.
The compressor fan was not running at the time i noticed everything stopped working. It still had power and the indicator light on the inside unit was on.
This unit has only one valve that gets opened and is also the service valve.
Im thinking just to have a service tech come out.

 

[WorthFlorida]

I found a youtube on a Fujitsu mini and it does have two valves but only the low pressure side have a fitting for a gauge.

 

[Jorgebaloy]

Its been a while since ive been on here.
Im in the process of installing two Fujitsu 18k minis. Single zone.
One is in place and set up. It will not cool. I did notice today when trying to trouble shoot that the inside of the outside compressor unit seems like it gets very hot. And took a very long time to cool down.
All wiring looks to be correct and seems to be straight forward.
Last weekend i ran it for about 20 minutes and when i noticed it wasnt cooling i shut it off until this weekend.
I let it run for about an hour...seemed to cool a little.
But then i noticed the outside unit was off and hot.
So i shut it off again. Looked at the wiring. It looks correct.
3 wires that connect the outside and inside units with a ground.
2 feed wires from the disconnect with a ground.
The only thing that im not sure if it would effect anything is the install kit come with a surge protector. Which i wired in the breaker panel to the breaker for the mini.

What are the causes of compressor overheating:

High Head Pressure - This can be caused by dirty condenser coils, a bad condenser fan motor, a recirculation of air back into the coils, improper rotation of the condenser fan, non-condensibles (air, nitrogen or other gas), and an overcharge of the refrigeration system. Another thing found that can cause this is an extra heat source near the condenser such as a dryer vent which can introduce extra heat into the system.

Improper Voltage - This can be a power company issue that needs to be corrected by the power company especially high voltage but low-voltage can be a problem in the circuits providing power to the compressor. Lose connections and corroded wires or terminal connections can cause low voltage and high amperage problems that result in compressor overheating. This can also be the result of a power company transformer issue along with the high voltage problem.

High Superheat - this can result from a low refrigerant charge, a restriction in the refrigerant piping or a faulty metering device. It can also result in a liquid line too close to a heat source such as hot water piping loops. In that case, the liquid line needs to be insulated from the hot water piping or relocated.

Short Cycling Compressor - this can be caused by a low charge or faulty metering device. Air flow across the evaporator coil can also result in this issue and can be from a dirty or clogged air filter or frozen evaporator coil. A bad capacitor can also cause the problem.

Other Possible Causes - A failure of the internal overloads inside the compressor or bad compressor valves can cause issues with overheating. These problems can be difficult to resolve in hermetic compressors without replacing the compressor. Heat pumps with faulty reversing valves can also be an issue.

 

[Dana]

You realize you're responding to a thread that is more than 6 months old, right?