$300?, that's quite a bit for a cap change. If you wind up doing your own in the future be careful, you MUST be sure power is off from the entire system and the caps have to be hooked up correctly or else it might self destruct. Seems the extreme heat of this summer has pushed a lot of caps over the edge..
$300?, that's quite a bit for a cap change. If you wind up doing your own in the future be careful, you MUST be sure power is off from the entire system and the caps have to be hooked up correctly or else it might self destruct. Seems the extreme heat of this summer has pushed a lot of caps over the edge..
SandEagle
Lifer
- Aug 4, 2007
- 16,809
- 13
- 0
not so much the heat but perhaps the voltage spike from the outage? thats what i was told anyway. $200 for me, but the guy did stay an hour and run several checks on condenser and internal system.
someone have a link to a good, reliable, cheap volt meter?
Yea, a spike sounds like possible culprit. You could look at Harbor freight or Ebay for a DMM, a $25 cheapie will be good enough, here is some instructions on how to test a capacitor with a DMM (when it's disconnected)...
"To use a multimeter to check your capacitor is working effectively you need to set the meter to the high ranges 10k - 1m and connect the probes in the same way as the capacitor tester, black to ground red to power, as soon as the probes make contact the meter should swing near zero then slowly move toward infinity before coming to a rest at infinite ohms as the capacitor is being charged by the battery in the multimeter. If the capacitor is bad then the meter will go to zero ohms and remain there, if this is the case then this is known as a shortened capacitor.
In the case of an open capacitor there will be no ohm reading and some capacitors have a dielectric leakage, you will know this if the ohm-meter comes to a rest at a point before infinity but please check this against a known working capacitor."
I would try a new one even if it tested good with a DMM, these caps face large voltages and extremely high heat working conditions..
Hey, sorry to hijack, but this thread is active and just helped me replace the run motor capacitor in my A/C unit.
I found a local electrical supply shop who sold me a new capacitor.. I installed it and it's working, however, one number was different and I wanted to understand what it means and if it will cause issues.
The GE 97f9838 is:
40/5 MFD, 440VAC,
The one that I got local is:
45+/5 MFD, 440VAC
Is that a big deal? Am I going to burn out my AC motor or anything?
I found a local electrical supply shop who sold me a new capacitor.. I installed it and it's working, however, one number was different and I wanted to understand what it means and if it will cause issues.
The GE 97f9838 is:
40/5 MFD, 440VAC,
The one that I got local is:
45+/5 MFD, 440VAC
Is that a big deal? Am I going to burn out my AC motor or anything?
Mixolydian
Lifer
Yes, capacitance ratings MUST be identical, however voltage ratings can differ as long as the new cap is rated at the same or HIGHER voltage than the old one.
Capacitors should not be installed that are not within %5 of rated value.
Except as noted above you may use one with a higher voltage rating.
I would order one of the correct value. Order a spare if you are not sure of the manf. Some of the made in China ones are failing in less than 2 years.
.
Capt Caveman
Lifer
- Jan 30, 2005
- 34,543
- 651
- 126
That depends on many factors. Moisture in the contactor causes them to burn over time as does dirt. A lot of times it is ants. If it is an exposed contactor then you can actually look at the contacts and see how burned they are but that really does not always tell you it is time to replace. At some point the contacts will burn enough that they will no longer carry enough amperage to function properly. The one at my lake house started chattering, rapidly making and breaking contact.
If your unit is 5 years old or older and you are going to take the cover off you might as well just replace the thing. It is a 5 minute job. Just make sure the power is completely off to the unit. You can buy the new type that is totally closed to prevent ant and bug contamination for less than $10 at a supply store. The last two I bought, one to replace and a spare, were $8 a piece.
These are EASY to replace and CHEAP parts guys. If you are comfortable around electrical items and can use a nutdriver/screwdriver and a pair of pliers then you can change these things easily. Pull the wire clips off spade type connections with a pair of needle nose pliers directly on the back of the clip to prevent breaking the clip off the wire.
If you are into preventative maintenance just replace these items every 5 years or so and keep a spare on hand just in case. Once you have changed either of these items you will be able to do it in the dark back yard at 3 AM if need be in minutes and not have to sleep sweating.
slag
Lifer
- Dec 14, 2000
- 10,473
- 81
- 101
If you get a capacitor that is 40/5 you can use one that is 35/5
The /5 means it is within + or - 5 microfarad. Both are essentially identical.
Dont listen to my explanation as it is wrong, however, you can use a 35/5 in place of a 40/5 since the variance is enough to make the tolerances/ratings close enough.
The /5 means it is within + or - 5 microfarad. Both are essentially identical.
Dont listen to my explanation as it is wrong, however, you can use a 35/5 in place of a 40/5 since the variance is enough to make the tolerances/ratings close enough.
Last edited:
PottedMeat
Lifer
- Apr 17, 2002
- 12,363
- 475
- 126
40/5 means it's 2 capacitors, 40uF for one, 5uF for the other, with a common terminal. 40/5 +/-10% means the value can vary + or - 10% for each cap.
slag
Lifer
- Dec 14, 2000
- 10,473
- 81
- 101
Thanks for fixing my incorrect information. I remember reading up what the terms meant, and in my head I knew that one would replace the other, but when I typed it out this morning, I had the numbers all twisted around.
I'd blame it on lack of sleep, but I slept well.
If a 45/5 is installed in place of a 40/5 that is already more than 10% out of spec.
Add the 10% +- tolerance and it may be running ~20% out of rating.
Which will shorten the life of the motor.
.
Add the 10% +- tolerance and it may be running ~20% out of rating.
Which will shorten the life of the motor.
.
Okay, my wife ran by the electrical supply store with a pic of the original GE part. They gave us the correct one and just asked that we return the other tomorrow. Sweet! It ran properly all night and finally got the house down to a reasonable temp... I'll swap out for the exact part tonight and we'll be set. Since we're talking A/C... I noticed that the rear of the unit has a lot of lint or other things clogging the vents, can I hose this out or do I need to use another technique? I've seen people suggest paint brushes... The other 3 sides are totally clear, but I'm assuming I'm losing some effectiveness by having one side pretty well filled up.
slag
Lifer
- Dec 14, 2000
- 10,473
- 81
- 101
With the tolerances listed, the 35/5 part falls within the tolerance of the 40/5. No damage will be done. Same with a 40/5 and 45/5. You won't see any noticeable shortened life of the motor.
If you put a 40/5 cap in and it was operating at -10%, it would be running at 36/5 which is basically the same as 35/5. I agree it would be best to replace like with like, but if you needed to, you could use the 35/5 and it would work fine.
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brianmanahan
Lifer
- Sep 2, 2006
- 24,547
- 5,958
- 136
lxskllr
No Lifer
- Nov 30, 2004
- 59,067
- 9,469
- 126
Education's for dweebs. I just tear shit apart, and figure it out. this is my latest project...
Good as new. and I didn't need none of that fancy education.
Good as new. and I didn't need none of that fancy education.
Red Squirrel
No Lifer
^ I see it's setup for racing and better airflow. How many turbos did you manage to fit in that bad boy?
Captante
Lifer
- Oct 20, 2003
- 30,337
- 10,854
- 136
Education's for dweebs. I just tear shit apart, and figure it out. this is my latest project...
Good as new. and I didn't need none of that fancy education.
Needs big googly-eyes around the headlights!
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