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All transformer comes with a current limit specification in terms of VA units. For example a 24 v secondary coil with 6 VA specification only can hold a current of of 4 amps for a short period of time. So to prevent that it burned out you only pass an 80% of that current, then it really can hold 3.2 amps continuously.
Other possibles causes for burning the transformer are:
1. Accidentally connecting the primary and secondary reversed, the secondary can not manage the voltage and current of the primary .
2. A coil or device that is connected to the secondary is demanding to much current because is shorted or stuck in a position causing an increase on current.
3. The primary have multiple taps to operate on different voltages and the combination is wrong.
3. Faulty wiring. Some times the insulation of the wires became worm, cracked or melted, with the wires torches the metal a short is produced and the transformer burns. Check the wires carefully.
If you have an open primary wire, this means the transformer, or one of the Hot wires coming into the unit may be tripped. Check your breakers to see. If it is the transformer at the furnace, the primary side is the 120 volt side of the transformer. The 24 volt side will be dead due to this, as it is the secondary side. If you find you have power going to the indoor unit, but nothing is working, you will need to replace the control transformer. It is 120 Volts primary side X 24 volts on the secondary side. They only cost about $20.00 and are easy to change out. Primary side you will have a blk and wht wire. You may have several wires on the other side, but it will tell you in the directions which 2 wires to use to get 24 volts, very east to do. Look on the diagram and it will show you where the transformer is at the start of the run on the furnace. Again, it may be a blown fuse if you have a fuse box, or a tripped breaker. It will be the incoming side, that is the primary. Please rate me on my help to you. Shastalaker7 A/C, & Heating Contractor. PS, If you need my help contact me.
Remove the thermostat face and place a jumper between R and Y. The outside unit should come on. If it doesn't, check for 24vac between R and C or R and Y. If you don't have it then you need to check the transformer. Check for 24vac on the transformer secondary and 120vac on the transformer primary. If you don't have power on the primary, check for a blown fuse or tripped breaker. If you do have power on the primary but nothing on the secondary, you need a new transformer. If the unit does come then the thermostat is the problem.
If the transformer is good and the unit doesn't start when you install the jumper then you have a problem in the outside unit. It could be the contactor coil which you can check with an ohmmeter. It could also be a low or high pressure switch or and overload all of which you can also check with an ohmmeter. Let me know what you find.
Look at the tranformer. It should tell you which wires are the primary side and which are the secondary side. It may have more than 2 wires on the primary so it can be used for more than 1 voltage. Now depending on what voltage the a/c uses find the wires in the a/c with that voltage on them (110v or 220v) and connect one of those 2 to the lead for that voltage on the primary and the other to the common on the primary. Next the secondary side should have 2 wires, probably yellow and blue but maybe not. I don't know the color of the wires in your a/c but one leg of the primary usually connects to a red wire and the other to a blue wire that probably come from a ciruit board or thermostat. Make sure you do not connect 110/220 to the wires for the low voltage side. If this doesn't help let me know what color the wires in your unit are and we can go from there.
Hi, I am not positive the control voltage to your thermostat will be on a RV a/c, most homes are 24 volts. I know yours would be less. If you have a 2-wire stat and this a/c is not working, take the two thermostat wires a touch and hold them together. Don't worry as this is safe and will not shock you. If the unit comes on and runs, you do have voltage there but the meter may be set wrong. If nothing happens, then you need to find the breaker for this unit to see if it as tripped. Reset it anyway. If still no power, you will need to find the transformer for this unit and check for power to it which will be high voltage/primary and power out which is the secondary low voltage which controls all low voltage controls such as the stat. If you have a wiring diagram on the condenser up top or most RV have a large book that tells you about your coache. If you have a diagram look for the thermostat as it will be labeled in the legend as a T with a circle around it or it may say stat. Follow to see where it gos from there, to the transformer or what and let me know. If the unit does fire when you jump out the stat wires, you will have to replace the stat. Please keep me posted on this. You may have a blown fuse up top cutting off power to the transformer also. You can ohm them out also. Keep me posted so we can solve this. Sincerely, Shastalaker7
You had a direct short. One of the wires shouldn't have been where it was. Tell me the color of the wires and the hook up.
rule of thumb from thermostat red to R White to W Green to G Yellow or Blue to Y no comm hook up from t-stat now the control for the ac is the Y terminal and the only wire left to Common. Generally speaking. Let me know the wire colors? ken
You need a serviceman. No really, you do! You are in over your head and you are replacing parts just because you can see them and they are not the likely culprit. I am betting it is the contacters in your condensing unit.
blown transformers are usually from a low voltage short the first thing i would do is wire a automotive or resetable 3amp fuse in line with the transformer so you dont blow transformer after transformer the wire coming off the transformer that say 24v take that wire a couple of inches down and cut it and install the fuse in series there
now you can go through your low voltage wires one by one and test them unhook all the wires to your outdoor condenser at your indoor unit(furnace or airhandler) and try turning it to cool now if you blow the fuse the short is between the tstat and the indoor unit if the fuse is still good leave it on cool and hook up one wire at a time to your outdoor unit starting with R a lot of times your contactor or your defrost board will short out on you also look for pinches in wires wires with cracks in the insulation and wires touching metal this situation can be a real pain sometimes i would recommend calling a hvac company if you start to get stumped
hope this will help you
pls on the transformer is writing each wire color to the corresponding voltage you have 2wires low voltage 24 volts(secondary) and other 2 wires power ( primary) also if you follow the uni wiring you will find 3 vwires main power voltage may be 110 or 220 or 380 and two others low voltage commonly 24 volts after identification you can connect each wire to the other .