I have a coleman mach series roof top ac unit that does not blow cold air but everything works on it. I found where the freon leaked out and can solder it but do not know how to refill the freon. Any advise?
The system needs to be accessed through what is call a tap valve. After a tap valve is in place a high vacuum should be pulled on the system down to 500 microns to remove air and non condensible gases along with any moisture from the system. Then the charge should be weight into the system according to the name plate with the proper type of refrigerant, generally Refrigerant 22. An alternate method is to charge the system by superheat of the gas returning to the compressor. Ambient temperature determines how high or low the superheat should be.
Look on tag to see what refrigerant it uses then go to walmart or other place and pick up a can or two along with a can of A/C oil and a fill hose with gage some come with it on the can, connect it to the low side scharder valve, the connector will only fit the fill valve. Then start the unit and turn on max, and check the gage it should be in the blue when fully charged.Turn the knob to pierce the can of refrigerant and hold can upside down as the A/C fills watch the gage then if you need more add the can of oil and then the second can of refigerant.keep going till you get to the blue full mark about 45, most times a vacuum is not needed as long as there is any refrigerant left at all trapped in system . a vacuum is needed if compressor or dryer ,or reservoir tank is replaced as these store excess air,liquid, and gas.just read directions on filling hose and gage and close tap valve. not much chance of any mistake.
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That should be a 30,000 Btu unit. Its been a while since I worked on them. The 78 is the series or model, the 30 is the capacity or btu's and the 901 indicates it is a Copeland compressor.
It is a closed system, which normally they don't require recharge. It can be done but it is more or equal expense as buying a new unit. A lot of times a real good cleaning by someone who knows how to do it properly is all that is needed in cases such as yours.
First of all, an extension cord and GFI receptacle to run an AC unit will almost always blow either GFI or circuit breaker or both due to large current draw from AC unit. If an extension cord needs to be used, keep it as short as possible, and use the heavier gauge that is approved for AC use. What happens when you use an extension cord, is the voltage drop that will happen by the time the AC gets power. With any voltage drop, the amperage draw increases, so a 15 amp circuit breaker will most likely trip. Nowadays, all AC units are wired with a minimum 12 gauge wire rated for 20 amps. You say nothing is happening now, is that to say that the fan only mode doesn't work on the AC unit either?
if the compressor started and stoped means
1 thermostat need settings
2 compressor over heated due to low suction pressure need to check and repair the leak then charge the freon
Sounds like you have either a bad fan motor or a bad fan motor capacitor. When you turn the unit on with the fan not working, the compressor (the humming noise) runs and gets real hot real quick resulting in the compressor cutting off ( the nothing after) on it's inside high temp switch. This is what the compressor is designed to do so that when this happens, it does not burn the compressor out. Replace you fan capacitor, give the compressor an hour to cool, then try it. In most cases and if I'm correct, the unit will run just like you want it to. Good luck.
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You will need 12 vdc (battery or converter) for controls to work, and 115 VAC (hydro) for fan & compressor to work. With your fan obviously working, that tells me you have both already but compressor may not be kicking in. Do you hear a "moaning" sound or see lights dim when switched to cool?
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