FUJITSU Heating Problem

[mark171]

About a year ago I bought a Fujitsu Hi-Wall Air Conditioning Model AOB18R1 (Cond) and ASB18R1 (Evap). The guys who installed forgot to plug one of wires and at the beggining the heating worked for 3 minutes and stoped for 3 minutes as a protection for hi-pressure caused for the missing wire. After a week the same guys who installed came back found out about the wire they forget to connect and everything seemed to be fine. But I noticed that doesn't matter how high I set temperature for heating the air conditioning works fine for about one hour and after that it blows a cold air at low speed for 3 minutes, this is a pain in the ass, because when the environment starts to get warm, the cold blow air starts ruining everything.
I am sure the environment is not overheated because I have thermometer inside that shows me the exact temperature, which is not higher then 71F/22C degrees.

Can you guys tell me if this is normal or what kind of problem do I have.

Thanks

[nike123]

Possible refrigerant leak! Find someone who will find leak first , then recharge refrigerant by weight. How long are pipes?

[ALONEI]

For some reason if I understand corectly what you wrote, it looks like the comp is stopped working and the coil is cooled by the fan.
Try to set the temp higher and see how it works.
If the unit is hang high then there will be a major diffrence between were you are and tha unit

Good luck

[paul_h]

Sounds normal. When it reaches setpoint, the outdoor unit stops, the indoor fan keeps running until it realises it's not heating anymore (cold air), then switches to monitor speed.
Otherwise it going on defrost mode (most units do this every 45min if the outdoor unit is in a cold area)
All air cons work like this.
If the outside is above 7C, defrost shouldn't happen, poor installation (closed in condenser), outdoor fan not working, or being short of refrigerant will cause unneccessary defrosts.
Pipe length?
is the indoor unit in the middle of the wall or in a corner?
Is the outdoor unit in a vacant area free from obstruction?
The outdoor ambient temp?
Can you see if the outdoor fan is working? (it may cycle on and off, but stick around for 10min and it should run at least once)

A good install with free air circulation through the outdoor and indoor, and put in a place where air doesn't directly blown on you, with the right pipe length, is the only to prevent poor heating from an a/c

edit: If the unit is a year old, have you ever cleaned the filters?

[mark171]

Sounds normal. When it reaches setpoint, the outdoor unit stops, the indoor fan keeps running until it realises it's not heating anymore (cold air), then switches to monitor speed.
Otherwise it going on defrost mode (most units do this every 45min if the outdoor unit is in a cold area)
All air cons work like this.
If the outside is above 7C, defrost shouldn't happen, poor installation (closed in condenser), outdoor fan not working, or being short of refrigerant will cause unneccessary defrosts.
Pipe length?
is the indoor unit in the middle of the wall or in a corner?
Is the outdoor unit in a vacant area free from obstruction?
The outdoor ambient temp?
Can you see if the outdoor fan is working? (it may cycle on and off, but stick around for 10min and it should run at least once)

A good install with free air circulation through the outdoor and indoor, and put in a place where air doesn't directly blown on you, with the right pipe length, is the only to prevent poor heating from an a/c

edit: If the unit is a year old, have you ever cleaned the filters?

I am sure it is not going on defrost mode, because the outside temp. is higher then 12 C and when the unit is on defrost mode a yellow light flashes.
I set the temperature to highest possible 30 C and the fan speed to high. The outside fan works for about 1 minute and stops for 3 minutes, the compressor never stops. The Pipe length is about 5 meters.
Is there a way to make the air cond. work in heating mode regardless if the set temperature was reached or not? just to check internal sensor.
Thanks

[paul_h]

Well the indoor pipe temperature sensor turns the outdoor fan on and off. If the fan is cycling off a lot on the outdoor, that means the indoor coil temperature is high (like 50C).
If the indoor unit is that hot but you're not getting effective heating, then you have a pipework, air flow or gas charge fault.
How is the filters, indoor evap coil and indoor fan for cleanliness?
How hot is the large pipe on the outdoor unit, have you got a thermometer to check it? If so, check the indoor evap coil temp too.
You could try "test mode", most fujis have a small button on the front of the remote, or two pins on the back inside the battery compartment you need to short out with a flat blade screwdriver. Test mode doesn't disable every control logic though.

[Brian_UK]

..... The outside fan works for about 1 minute and stops for 3 minutes, the compressor never stops. .....

That sounds like load control.

The compressor is overloading so the controls stop the outdoor fan to reduce the load on the compressor. When the load reduces the fan cuts in again.

[mark171]

That sounds like load control.

The compressor is overloading so the controls stop the outdoor fan to reduce the load on the compressor. When the load reduces the fan cuts in again.

Good, but what is causing this overloading?
Would be refrigerant leak ou too much refrigerant?

[nike123]

That sounds like load control.

The compressor is overloading so the controls stop the outdoor fan to reduce the load on the compressor. When the load reduces the fan cuts in again.

Nope, that is not inverter and doesn't have any overload control except internal thermal overload protection, which need at least half hour to cool down.

[nike123]

Good, but what is causing this overloading?
Would be refrigerant leak ou too much refrigerant?

If no one is charged refrigerant it cannot be to much refrigerant.
Does this behavior is present after day one or it is present only this winter season.?
If it is from day one than it is possible that you have restriction somewhere in refrigerant lines (line collapsed at sharp elbows maybe).
If it is present only this heating season and last one is worked OK, then it could be some amount of refrigerant leaking (High superheat and high discharge temperature).
Also, if indoor unit filter or heat exchanger is clogged or indoor fan has no proper speed it could be same behavior.

First thing to do is to check air quantity across indoor heat exchanger. If it is OK then it is necessary to recover and weigh refrigerant. If it is not OK then check fan and clean filter and exchanger.
Second, if we got to weighing refrigerant, then if weight is not OK it is necessary to find leak, repair leak, and weigh in correct amount of refrigerant (stated at nameplate). If weight is OK, then it is necessary to check connection pipes for collapsed tube!

Also, you say that they incorrectly wired this unit at beginning. It would be wise that someone triple check that wiring again, even I doubt that this is the case here, according to symptoms you are describing!

[mark171]

If no one is charged refrigerant it cannot be to much refrigerant.
Does this behavior is present after day one or it is present only this winter season.?
If it is from day one than it is possible that you have restriction somewhere in refrigerant lines (line collapsed at sharp elbows maybe).
If it is present only this heating season and last one is worked OK, then it could be some amount of refrigerant leaking (High superheat and high discharge temperature).
Also, if indoor unit filter or heat exchanger is clogged or indoor fan has no proper speed it could be same behavior.

First thing to do is to check air quantity across indoor heat exchanger. If it is OK then it is necessary to recover and weigh refrigerant. If it is not OK then check fan and clean filter and exchanger.
Second, if we got to weighing refrigerant, then if weight is not OK it is necessary to find leak, repair leak, and weigh in correct amount of refrigerant (stated at nameplate). If weight is OK, then it is necessary to check connection pipes for collapsed tube!

Also, you say that they incorrectly wired this unit at beginning. It would be wise that someone triple check that wiring again, even I doubt that this is the case here, according to symptoms you are describing!

Hi and Thanks,
When the guys who came to fix wired problem, they first thought it was leak or short of gas and they did charged refrigerant in it.
The unit works fine in the Brazil hot summner and cool the inside ok, but in the winter it doesn't, even when the outside is not too cold (12 degrees) and it has always been this way since a bought it a year ago.
The filters are clean because just use the air cond. a few times (around 40) and the fan speed are fine.

Appreciate your help.
Thanks again.

[mark171]

Well the indoor pipe temperature sensor turns the outdoor fan on and off. If the fan is cycling off a lot on the outdoor, that means the indoor coil temperature is high (like 50C).
If the indoor unit is that hot but you're not getting effective heating, then you have a pipework, air flow or gas charge fault.
How is the filters, indoor evap coil and indoor fan for cleanliness?
How hot is the large pipe on the outdoor unit, have you got a thermometer to check it? If so, check the indoor evap coil temp too.
You could try "test mode", most fujis have a small button on the front of the remote, or two pins on the back inside the battery compartment you need to short out with a flat blade screwdriver. Test mode doesn't disable every control logic though.

Hi Paul and thanks
I checked the indoor coil temperature and it goes from 44C to 48C. The the large pipe are pretty hot I cannot touch with my hands and my thermometer cannot measure it.
I forgot to mention the guys who came to fix wired problem, they first thought it was leak or short of gas and they did charged refrigerant in it. Do you too much could be the cause of the problem?
The filters are pretty clean.

Thanks again.

[nike123]

Then, first thing to do is to recover and weight refrigerant. If to much is in, then recharge correct amount by weight and see what is happening.

[paul_h]

^ I agree
It might be a gas leak.
Normal discharge temps are 70-80C, when a system runs short of refrigerant that temperature goes up, sensible temp goes up but there's not enough refrigerant to do any work to heat the room.
I'm wary though because you say it cools fine. Did you mean "it did cool fine" or do you mean it "still cools fine"?
Higher pressures are experienced on heat mode, so more refrigerant is leaked out if there's a bad join somewhere.
Could be the system has a leak, and they overcharged it to compensate, and now 1 year later there's significant refrigerant lost so it doesn't heat anymore.
Then again it could be that cooling works fine even now, but heating doesn't work due to a fault with checkvalves, capillary, reversing valve, EEV, kinked pipework or blocked distributor in the indoor unit.

First step is reclaim and weigh refrigerant first, so you don't blame the system components without proving nothing is wrong with the refrigerant charge.