Home Air Conditioning Guru's

[Drac0nic]

far as it goes the whole "hot line cold line" thing is correct. Look for burned wires or similar, if you have the cover off you should be able to feel the compressor. Do not cycle the thing on and off real quick, let it sit for about 5 minutes after you turn it off. They don't like that a lot. What happens when you start it up is it should have two hums, one by the fan (it'll have one common shaft fan probably) and the other by the AC compressor. The AC compressor should have a lower tone then the fans, and should have a sort of pulsating to it. If it doesn't have a pulsating to it, you probably have an electrical issue with the compressor that is causing the motor not to start. If that's the case, post and I'll go into more detail on it. Yes, I have worked on HAC before in doing rentals and such. (the ass end of the job market, trust me)

 

[Blown&Injected]

Oh yeah, it is also very common to check a cap with an analog VOM using, yes, the OHM scale!

They can be dangerous to mess with.

 

[Quick6'n'-K.C.]

Originally posted by Blown&Injected
Oh yeah, it is also very common to check a cap with an analog VOM using, yes, the OHM scale!

They can be dangerous to mess with.

i havent had any luck testing capacitors with a digi multimeter using the OHM setting, that is why i purchased a capacitor testor at graingers a few years ago-

what type of capacitors are you speaking of?
the ones i test are motor start capacitors on electric motors/ such as large fans, heaters, and big electric motors

PEACE
BW

 

[Blown&Injected]

Some DMMs have modes for capacitor testing. These work fairly well to determine approximate uF rating. However, for most applications, they do not test at anywhere near the normal working voltage or test for leakage. However, a VOM or DMM without capacitance ranges can make certain types of tests.
For small caps (like 0.01 uf or less), about all you can really test is for shorts or leakage. (However, on an analog multimeter on the high ohms scale you may see a momentary deflection when you touch the probes to the capacitor or reverse them. A DMM may not provide any indication at all.) Any capacitor that measures a few ohms or less is bad. Most should test infinite even on the highest resistance range.

For electrolytics in the uF range or above, you should be able to see the cap charge when you use a high ohms scale with the proper polarity - the resistance will increase until it goes to (nearly) infinity. If the capacitor is shorted, then it will never charge. If it is open, the resistance will be infinite immediately and won't change. If the polarity of the probes is reversed, it will not charge properly either - determine the polarity of your meter and mark it - they are not all the same. Red is usually **negative** with VOMs, for example. Confirm with a marked diode - a low reading across a good diode (VOM on ohms or DMM on diode test) indicates that the positive lead is on the anode (triangle) and negative lead is on the cathode (bar).

If the resistance never goes very high, the capacitor is leaky.

The best way to really test a capacitor is to substitute a known good one. A VOM or DMM will not test the cap under normal operating conditions or at its full rated voltage. However, it is a quick way of finding major faults.

 

[AZ Vic]

Watch out when you are messing with the cap... it'll bite the $hit outta ya!

As much as the AC guys nail you for... it would be worth picking up a spare cap and testing to see if it fixes it - if it doesn't, put in the old one and keep the new as a spare (climate controlled - they react alot like batteries) someday you will end up needing it. If yours is swollen - it is most likely bad.

If the cap doesn't fix it (make sure you clean that rust up and everything has good connections), and you have let it shut off for 30 minutes or so (allowing it time to thaw out if it froze over) - if niether thing fixes it - call a pro so they can diagnose it correctly.

If it has been getting steadily worse - I would bet that you have a slow leak somewhere and need some freon.

Good luck,

Vic

 

[Quick6'n'-K.C.]

Sounds good to me man-
when i have the lights go out in a 4000 watt light plant, i usually check for good AC generator power, good power to the box and then the capacitor- thats the reason why i have the cap testor, needed it in the field for right now answers to fix problems.

seems like you did some homework on the capacitors too-

i would have just hyperlinked the info

http://www.eio.com/repairfaq/REPAIR/F_captest.html#CAPTEST_004

section 4 is word for word

BW

 

[Quick6'n'-K.C.]

that post wasnt meant to be rude, just noticed that it matched your post

BW

 

[Blown&Injected]

Lots to explain and it was done better than I could have done it. BTW, it works for AC start caps and the text said it may be reproduced without proper cites and permission.

 

[TylerDurden]

update, my father inlaw (who's a maintence chief at a old folks home) and I have determined that its either the capacitor (which he will check (and has ones available) tomorrow, OR its the compressor itself.....lets hope for the former

 

[TylerDurden]

UPDATE
i wasnt able to aqcuire another capacitor but my dad's AC guy gave him some device that looked like a Cap (suppose to "boost" the weak cap) that was wired to the orig cap and we re installed it on the AC, attempted to light 'er off, no joy, but heard the compressor click.....at that point we assumed the comp was dead.....

so i call in a the orig installer, after paying 68 for the visit, he says its a burnt wire, and replaces a single connection.....10 bucks in parts.....WTF?????????? i was not here, the wife was, and the info i am giving you comes from her......i looked at every wire, every connection, nothing was burnt....my dad did too.....here's my next question, this house is only 4 years old, but im the 2nd owner (less than a year) should i be paying for anything????

 

[SloRegal]

Originally posted by TylerDurden
UPDATE
i wasnt able to aqcuire another capacitor but my dad's AC guy gave him some device that looked like a Cap (suppose to "boost" the weak cap) that was wired to the orig cap and we re installed it on the AC, attempted to light 'er off, no joy, but heard the compressor click.....at that point we assumed the comp was dead.....

so i call in a the orig installer, after paying 68 for the visit, he says its a burnt wire, and replaces a single connection.....10 bucks in parts.....WTF?????????? i was not here, the wife was, and the info i am giving you comes from her......i looked at every wire, every connection, nothing was burnt....my dad did too.....here's my next question, this house is only 4 years old, but im the 2nd owner (less than a year) should i be paying for anything????

A/C and Heating is what I do for a living, sorry didnt see your post sooner. It could have been a burnt wire, the most common place where wires burn is where the wires tie into the compressor itself due to being loose. There is little cap on the side of the compressor could be rectangle or round depending on what type of compressor it is. If you want you can take that cap off and see if any repair was made(make sure high voltage power is off).

About you paying anything. What was the parts that were $10?? Since house and the equipment is 4yrs old his labor warranty should have been up, usually 90days to 1yr. Since it was just a wire and not an actuall part that failed like a contactor, capacitor, fan motor..etc. there was no part to warranty. Warrantys is usually 10yr compressor/5yr parts or 10yr comp./ 10yr parts depending on brand and SEER rating. In other words you should have been charged Service Call and Labor.

P.S. After 4years you might wanna get evaporator coil and indoor blower wheel cleaned... If you havent already..