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Francis, Home Appliance Technician
Category: Appliance
Satisfied Customers: 2086
Experience:  been working with refs, fridge, washers. dryers. dishwashers, microwaves for the past 12 yrs .
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I have a greenhouse with two window air conditioners mounted

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I have a greenhouse with two window air conditioners mounted one on top of the other. I attached a max/min recording thermometer to the outlet vanes of each. These are the readings over the past 24 hours:


Current RH 84%

High RH 99%

Low RH 79%

Current Temp 50F

High Temp 61F

Low Temp 48F


Current RH 99%

High RH 99%

Low RH 80%

Current Temp 63F

High Temp 66F

Low Temp 61F



The actual temperature range over the past 24 hours was probably 61F - 86F.


At the time I recorded this info, the outside air temp was probably 63F.



Does the second unit have a problem? Any idea what is wrong? Thanks.

Hi, welcome to Just Answer. My name is XXXXX XXXXX I will be helping you with your problem today. If anything isn't clear, please just ask me.

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Its possible there is a fault here.
Can you tell me the make and model numbers, so I can pull up some technical information on these, please?
Customer: replied 4 years ago.

The unit is made by Zamil which is made in Saudi Arabia. I don't believe they are sold in the US. Do you have access to Zamil info? Thanks.

Thanks for the information.
Unfortunately I cant find any technical details on this, so ill opt out while I continue to look.
This opens the question to others as well
If any of us find an answer for you, we will respond and you will get a message from the site.

In the meantime, please DO NOT rate or respond to this message, as that will lock the question


Customer: replied 4 years ago.

I just got home from work and checked the temperatures. The "bad" unit is currently blowing 52F air.


Why would it sometimes blow ambient temperature air?


It seems like it blows ambient at night and cools during the day. This may be my imagination. I'll continue to watch it to see if this trend continues.

Thank you for using Just Answer. I will be glad to assist you in your answer. Think about safety when doing repairs, electric, water, gas, ect.

I have not seen one of these window unit before, but they are all made pretty much the same. This is one that fits into a wall, where the cool air blows inside, and the warm air blows out the other side, which is on the out side portion of the wall....correct?
Customer: replied 4 years ago.

Yep. Typical 1.5 ton window ac unit...



Ok, The unit that is not cooling as well, may just need the condensing (outside) coil sprayed cleaned with a water hose. The coil, if dirty (normally on the fan side of the coil), get cause the compressor to get too hot, and overheat. Cleaning this coil may solve the issue, and is very common on service calls for the issue you are describing. If this information has assisted you, please give a great rating. If not, please respond back for more information....Thank you
Customer: replied 4 years ago.

Nope. Coil was clean and it still isn't cooling. I'm puzzled because sometimes it blows 50F air and other times it just blows ambient air with 99% humidity. What would cause that? The other unit blows 50F continually.



When the unit is just blowing ambient air, is the compressor running?
Customer: replied 4 years ago.

How can I tell?


I will have to opt out, I do not have diagram of this unit to help you further. Maybe another expert might have something to assist you....thanks
Customer: replied 4 years ago.

Info for you (or whoever picks this question up).


I don't think the compressor is running because this unit is practically silent when powered up compared to the "good" one.


Would the fan run if one if there was a problem with one leg of the 220?


It seems the professional has left this conversation. This happens occasionally, and it's usually because the professional thinks that someone else might be a better match for your question. I've been working hard to find a new professional to assist you with your question, but sometimes finding the right professional can take a little longer than expected.

I wonder whether you're OK with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you!


Customer: replied 4 years ago.

I have verified that the 220v to each unit is ok.


Yes, I am still interested in help from an expert.


We will continue to look for another Professional to assist you.

Thank you for your patience,

Let me continue where you and the past experts have left.

Yes, I would say that the compressor is stopping that is why it would blow ambient air.
The question is why?

What controls the compressor is the thermostat. If you have a mechanical one, have you set it to the coldest setting just like the other one?

If you do, then you should try to jump the thermostat temporarily to take it out of the equation.

By the way, are you electrically inclined to do that?

If you think you are, think safety first. Un plug the unit first before doing any electrical wirings.
Connect the two wires hooked to this thermostat then observe the unit again if it would again record the same high humidity and ambient output temperature for the next 24 hours.

If it does not make it anymore, then I would say you have a bad thermostat.

But if it would still do the same thing, then I would say you could have an over heating compressor.
All compressor have thermal overloads. These are inside the windings to protect them from over heating. It could be a defective thermal overload, or a compressor that is overheating because of overload on mechanical issue, or a winding that has change its resistance due to age and is now drawing much greater current than it used to draw.

You can test this if you would happen to check the unit while it is not blowing cold air if there is still voltage present on the terminals of the compressor. Again, be careful working with live voltage.

If there is presence of voltage on the compressor terminals and the compressor is not running, then the thermal overload inside the compressor has tripped. It would take more than 2 hours for the thermal overload to reset by itself.
That would explain the unit blowing ambient air even though it is set to cool the room.

Let me know what you found out. If you have an ammeter, that would help us more in troubleshooting your unit.

Customer: replied 4 years ago.

Some of the info I provided may not have been correct.


Yesterday I moved my 2 recording thermometers. One is now mounted to the outlet vanes of the AC and the other is now outside the greenhouse.


Over the past 24 hours the outside temperature has been 61-85F with 40-81% RH and the AC output air has been 50F-66F with 66-99% RH.


Does it sound like this AC is functioning properly? Should the output be colder?


The reason I am suspicious is that the other AC unit puts out 50-55F air while this one is putting out 65F.


I want to be able to maintain my greenhouse below 90F this coming summer when the outside air is 120F.


The greenhouse is 36'L x 12'W x 7'H and the 2 window AC units are each 1.5 tons. The roof is clear vinyl .012" thick and almost horizontal. It is covered in dust/sand so it does not let all of the sun through. Does it seem possible that I can keep it below 90F?




Based on your readings, I would assume that the suspected unit did blow 66F when the ambient could be 66 F also and the compressor was off. Meaning , it is blowing ambient temperature.

Comparing to the other one which does not rise above 55F the air it is blowing. I would say, this good unit is running continuously. Meaning, compressor does not stop.

Do they have a mechanical thermostat? and Where are they set? Maximum on both units?

Would you know what time did the suspected unit blow 65F? You may know what could be the ambient during that time it blows 65F.

Regarding your question if it could keep up during the summer season, are you going to use only one unit at a time or are you going to switch them both at the same time?

Customer: replied 4 years ago.

Yes, both units were on high the whole time.


Not sure if the thermostat is mechanical. It has a long crimped copper tube mounted in front of the coil. I could easily bypass it if that would help you diagnose.


I have a digital multimeter but not a clamp-on ammeter. I'm not afraid to poke around inside the unit to get readings.


That would be a mechanical thermostat. The high setting that you are telling could be the high cool setting, meaning, the compressor is on and the fan is on high speed. There could be another knob near the control switch and that would be the thermostat.

Please trace that crimped copper tube at the front of the evaporator coil. That would be the thermostat. If you can by pass it, that would be great. Then record again the reading with in 24 hours and we would know if there is a difference.
Be careful working with live power. Always be safe. Un plug the unit first before doing anything on the unit.

Customer: replied 4 years ago.


The thermostat had 4 wires.


Red - ?

Orange - ?

Yellow - to the capacitor

Brown - one leg of 220


The wiring diagram is too faded to read.


Which do I connect to bypass the thermostat?





It would be hard to tell since you have 4 wires. The other two could be for the fan to stop as well when the compressor stops. This is a form of an energy saver. The other two would be the contact of the compressor. Can you trace the red and orange wire where it went to?

Another solution that i could suggest is for you to monitor the voltage going to the compressor. Monitor this while the unit is blowing ambient temperature, meaning the compressor is not running but the thermostat is set all the way to the coldest setting.

This would tell us if the compressor has power but not running so we would conclude that it stop through the internal thermal overload.

Customer: replied 4 years ago.


I checked the voltage at the 3 wires on the compressor while the fan was running and the switch was on high cool. The compressor was not running.


The voltage was:

A-B 220V

B-C 220V

C-A zero


What does this tell us?




Thank you for those info.

This would tell us that the thermal overload is tripped because there is presence of voltage and yet the the compressor is not running.

If this is the case, the compressor is over heating.
It could be if the condenser is dirty. ( it was verified that the condenser coil is clean)
Or the windings has reached its limit where in it draws much current now than normal and would become much warmer than normal that it would trip the thermal overload.
Or the thermal overload itself has been damaged and has been tripping even though the temperature of the winding is normal.

Either way, the compressor needs to be replaced since there is no easy repair on the thermal overload.

There is an alternative solution though temporarily but it would not be cost effective.

What we sometimes do is spray the condenser coil with mist of water. Just enough to bring down the pressure of the condenser to bring down the temperature of the compressor and it might prevent the compressor from stopping.

You would just loose some water on the process.

Francis, Home Appliance Technician
Category: Appliance
Satisfied Customers: 2086
Experience: been working with refs, fridge, washers. dryers. dishwashers, microwaves for the past 12 yrs .
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