How do I test the capacitor of an Airconditioner that is in series with the compressor , also would another value work as the 35uf one is hard to find where 30 or 40 are availiable Thanks Eldred

Appears to be a capacitor start induction motor? Please always include full 'make model (what it is)'.
2000 - PTH491A01 Abstract: PTH491 PTH7M PTH491B PTH491A murata pth7m CSR B capacitor start induction motor capacitor start run motor permanent split capacitor induction motor
Text: PTH7M330MD3 PTH491 Series PTH491A01AR3R3N160 PTH491A01AR4R7N180 PTH491A01AR6R8N200 PTH491A04AR6R8N225 PTH491A01AR100N225 PTH491A04AR100N315 PTH491A01AR150N250 PTH491A04AR150N355 PTH491A01AR220N300 PTH491A04AR220N400 PTH491A01AR330N355 PTH491A04AR330N450 PTH491A01AR470N400 PTH491A04AR470N500 Resistance Value (Ohms) at 25°C 33 ± 20 , PTH491A01AR3R3N160 4.5 15 SPECIFICATIONS Resistance Value (Ohms) at 25°C Fail-Safe Plug on Type PTH7M Series , No. 187 STARTING SYSTEMS OF MOTORS Type PTH491A01 PTH7M-B3 Starting PTH491B01 Capacitor Start

The videos in here might help you test and diagnose

https://www.google.com/search?safe=off&rlz=1C1QJDB_enCA643CA644&sxsrf=ALeKk01mSl_owI3xivd-EfTNmFVnNiSBHQ%3A1613586207983&ei=H18tYITEO4md_QavnK2QDw&q=testing+capacitor+start+induction+motor


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You'll need a clamp on style ammeter to check it. On the data plate of the unit, look for the "LRA" Locked Rotor Amps value. Clamp the jaws of the ammeter around just one of the large black wires connected to the compressor and try starting the unit while observing the reading on the meter. If it's close to the value on the data plate, then your compressor is indeed locked. A bad start capacitor could be the culprit too

You need to check the Amp draw at start up of the compressor. Also if you have a meter that can check the compressor capacitor, it needs to be checked. If the capacitor is ok and the compressor starts at a higher Amp draw than the rating on the capacitor, you will need a start capacitor.

Hi,
The compressor start capacitor may be bad or the compressor it's self is bad and cannot get started...

Here is a tip about troubleshooting your airconditioner...
There are many things that can cause your air conditioner not to cool...

AirConditioner Trouble - Review the Possibilities

heatman101

The value is on the capacitor, but if you can't read it, you need the model number of the compressor and you can call a appliance parts store and they should be able to help you.

If the fan is running but its just room temp air your compressor is not running. You can usually hear the compressor kick in and hum. If its an older unit it may be the capacitor or a melted wire. The wires are easy they are mostly located behind the access plate that the switches are hooked to just take the plate off and look for burnt ends or melted wires. replace or trim wires buy a wire connector kit from a hardware store. If the wires are fine it may be the start capacitor for the compressor or the wires going into the compressor ck them first. The capacitor is a grey or silver metal can or oval can with writing with 5uf 330v (approxamately) on it for the fan and 35uf 440v )approxamately) for the compressor. You can ck the capacitor yourself but do not touch the ends a capacitor stores voltage I usually ground them together with a screw driver to cancel out the voltage. If you have or buy a volt/ohm meter you can put it on ohms (buy it at most hardware stores 10 to 15 dollars for a cheap one) then touch the meter leads to each terminal on the capacitor after 15 seconds switchthem the meter will slowly build up to 5 or 35uf. Be careful and make sure the AC is unplugged respect the electricity. good luck

If it tripps quickly you have a direct short which means a hot wire is going to ground. This can be caused by a wire that has melted and grounded, compressor burnt out, fan motor failure, capacitor shorted, or just one of the wires running from the above to each other. First try the unit with it just running the fan.. if it does not blw the breaker then turn it to a/c . If it blows the breaker on fan you have a wire probably shorted inside the selector/fan panel open it up and look for melted or burnt ends repair the wires if found wires slowly degrade and that creates heat which causes the wire to degrade more until something melts. If it only tripps when you put it on a/c then you need to ck the panel and then go on top and take the cover off look for damaged wires ect there is an access after you take the cover off to get at more wiring. Look for a capacitor it will be a silver or grey cannister with writing on it that says 5uf or 35uf and 200 to 500volts if it is 3 wire it will be the start capacitor for the fan and the compressor if not then you should have two capacitors on 5uf and one 35uf make sure the wires look good if bad replace wires and try the unit if not you will need to purchase a volt/ohm meter at a hardware store get a cheap 10 to 15 dollar one it will come with instructions or just ask the salesman. Then you will need to unhook the wires from the capacitor. 3 wire put ohm meter on ohms and place the wires from the center connection to the outside connection one side will be for the fan and one for the compressor. When you place the black on the center and the red on the outside connection and then reverse hold them for a few seconds the meter will drop and build up to 5 or 35uf then do the other side. The center connection is the same for both sides. If you have one or two two wire capacitors you ck them the same way just put your ohm meter leads on and them switch and see if it builds up try a couple times. If they ck bad replace it. If not then your fan motor or compressor are bad. Remember th capacitors store voltage and are hot even when the power is off you can short them by using a screw driver blade do not touch with your hand. You can check he compressor by grounding one of your ohm meter leads on the compressor scratch a silver spot for goodconnection then touch each of the 3 connections on the compressor if any of them show 0 ohms or close its shorted out. Always unhook power before handling the unit or testing for ohms. hope this helps

You can get capacitors from any electric motor repair/rebuild shop if your capacitor is a 3 wire it will be a 5uf 30uf capacitor the fan motor runs off the 5uf the compressor runs off 30 or 35uf it will also have 440v 330v ect under the 5uf or 30uf this is the voltage as long as the replacement capacitor is within 5% it will not hurt anything. Capacitors usually run 5 to 15 dollars at a repair shop much more from duo them. good luck

Check outside unit to see if compressor is running. If compressor runs and fan does not. Check to see if fan is hot. If it is you have stuck fan motor,bad capacitor or bearing are out. Capacitor is located in wiring compartment,it is a silver canister with 3 terminals at top. Check to see if swollen or oily. If it is bad look on side of capacitor and it will tell you size. It will say 35uf 5uf 370 or 440 something like that. But that is the size. Rus

The capacitor is in an electrical box under the plastic shroud on top of your unit. Of course never open any of this up with the electric on. If you want to replace the capacitor you want to exact match up the voltage and microfarads
Example 370v 35uf(microfarads) compressor 5uf(microfarads)fan.
One problem, even though replacing a capacitor is a fairly easy prospect, most reputable supply houses don't sell to the public for safety reasons. Good Luck